JP6977458B2 - Hydrometallurgical method for nickel oxide ore - Google Patents

Description

The present invention relates to a hydrometallurgical method for nickel oxide ore by a high pressure acid leaching method using sulfuric acid.

In recent years, as a wet smelting method for nickel oxide ore, a high pressure acid leach method using sulfuric acid has attracted attention. In this method, for example, as described in Patent Document 1, a leachate step of immersing a slurry of nickel oxide ore in sulfuric acid at high temperature and high pressure to obtain a leachate slurry consisting of a leachate and a leachate residue, and a leachate adhering to the leachate residue are used. Solid-liquid separation step to separate, neutralization step to neutralize leachate, sulfurization step to generate nickel sulfide by blowing hydrogen sulfide gas into the neutralized leachate to separate poor liquid, in poor liquid to neutralize poor liquid It consists of a sum process and the like. Further, in this method, nickel sulfide having a nickel grade of about 50% by mass can be obtained from nickel oxide ore only by wet treatment, and it is not necessary to rely on dry treatment such as reduction and drying steps, so that it is energy-wise and cost-effective. It is advantageous to.

In the leaching step, in addition to nickel to be recovered, impurity elements such as iron, magnesium, manganese, and aluminum are also leached by sulfuric acid, so that excess sulfuric acid is required for the treatment. In order to reduce the amount of sulfuric acid used, for example, Patent Document 2 discloses a method of removing low nickel-containing particles from a slurry of nickel oxide ore and then supplying the particles to the leaching step.

Japanese Unexamined Patent Publication No. 2013-256691 Japanese Unexamined Patent Publication No. 2016-156063

However, since the low nickel-containing particles also contain a small amount of nickel, if the low nickel-containing particles are removed, the total amount of mined and transported nickel cannot be utilized. That is, when the pretreatment of the ore slurry of nickel oxide ore performed to reduce the amount of sulfuric acid used in the leaching step is performed, the removed low nickel-containing particles are not discarded, but the low nickel-containing particles are used. It is preferable to make effective use of nickel contained in a trace amount to further improve the nickel recovery rate.

The present invention has been made in view of the above problems, and is new and improved so that the recovery rate of nickel can be further improved without significantly increasing the amount of sulfuric acid or the like used in the leaching step. It is an object of the present invention to provide a method for hydrometallurgical nickel oxide ore.

One aspect of the present invention is a wet smelting method for nickel oxide ore that is recovered by leaching nickel from nickel oxide ore using a high-pressure acid leaching method, and is an ore slurrying step for sieving the nickel oxide ore. In the ore slurry obtained through the ore sieving step, the proportion of particles having a particle size of less than 45 μm is 10% by mass or more and 30% by mass or less, and the proportion of particles having a particle size of less than 45 μm is coarse. 3. The specific gravity of the coarse grain portion separated in the first separation step and the coarse grain portion separated in the first separation step, which is separated into fine grain portions higher than the grain portion and supplied to the leaching process, is 4. A second separation step of separating into a heavy specific gravity portion having a specific gravity of 0 to 5.0 and a light specific gravity portion having a specific gravity of 2.7 to 3.7, and supplying the heavy specific gravity portion to the leaching process, and the second separation. The vibrating sieving step in which the light specific gravity portion separated in the step is separated into an upper sieve and a lower sieve by a vibrating sieve having an opening of 300 μm or more and 500 μm or less, and the ore slurry under the sieve is supplied to the leaching process, and the above. The first separation step comprises a crushing step of crushing the high magnesium-containing particles recovered on a sieve so that the particle size of 80% by mass of the particles is less than 100 μm, and the first separation step turns the ore slurry into a hydrocyclone. It has a classification separation step of supplying and classifying and separating, and a specific gravity separation step of supplying the underflow classified by the hydrocyclone to the density separator and performing specific gravity separation in the classification separation step, after the specific gravity separation step. The underflow is the coarse grain portion, the overflow after the classification separation step and the overflow after the specific gravity separation step are the fine grain portions, and the high magnesium-containing particles crushed in the crushing step are discharged by the leaching process. It is characterized by being added to a sulfuric acid-acidic leaching slurry.

According to one aspect of the present invention, by adding the pulverized particles obtained by pulverizing the high magnesium-containing particles separated by the pretreatment to the leaching slurry, the sulfuric acid remaining in the leaching slurry is contained in the high magnesium-containing particles. Since the nickel can be additionally leached out, the residual sulfuric acid is neutralized by this additional leaching, and the amount of the neutralizing agent used is suppressed. It can be increased further.

In this way, the ore slurry can be accurately separated into underflow and overflow according to the particle size.

In this way, after the classification separation is performed on the front stage side where a large amount of ore slurry is processed, the specific gravity separation is performed on the rear stage side where the processing amount of the ore slurry is smaller than that on the front stage side, so that the ore slurry is efficiently coarsened. It can be separated into a grain part and a fine grain part.

By doing so, it is possible to suppress the residual of low magnesium-containing particles on the sieve and the increase of contamination of high magnesium-containing particles under the sieve. Therefore, while further improving the recovery rate of nickel, sulfuric acid and a neutralizing agent can be suppressed. The amount of water used can be suppressed.

As described above, according to the present invention, the amount of nickel recovered can be further increased without increasing the amount of sulfuric acid used in the leaching step.

It is a process drawing which shows an example of the flow of the wet smelting method of nickel oxide ore which concerns on one Embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described in detail. It should be noted that the present embodiment described below does not unreasonably limit the content of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as the means for solving the present invention. It is not always the case.

First, the flow of the hydrometallurgical method for nickel oxide ore according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram showing an example of a flow of a hydrometallurgical method for nickel oxide ore according to an embodiment of the present invention.

The hydrometallurgical method for nickel oxide ore according to an embodiment of the present invention is a smelting process for leaching and recovering nickel from nickel oxide ore using a high-pressure acid leaching method (HPAL method). As shown in FIG. 1, the wet smelting method for nickel oxide ore according to an embodiment of the present invention includes an ore slurrying step S1, a sorting step S2, an ore slurry concentration step S3, a leaching step S4, and a solid. It has a liquid separation step S5, a neutralization step S6, a sulfide step S7, a final neutralization step S8, and a pulverization step S9.

In the present embodiment, the ore slurry is provided with a sorting step S2 for separating the high magnesium-containing particles contained in the slurried ore before the leaching treatment with sulfuric acid, and the high magnesium content separated by the sorting step S2. The particles are crushed in the crushing step S9, and the crushed particles obtained in the crushing step S9 are added to the leaching slurry. Hereinafter, each step of the hydrometallurgical method for nickel oxide ore according to the embodiment of the present invention will be described in detail.

(1) Ore Slurry Step The ore slurry step S1 slurries nickel oxide ore. Specifically, in the ore slurrying step S1 of the present embodiment, the nickel oxide ore, which is the raw material ore, is classified at a predetermined classification point to remove oversized ore particles, and then the undersized ore particles are removed. Add water to the ore slurry to make an ore slurry.

Here, the nickel oxide ore, which is a raw material ore, is an ore containing nickel or cobalt, and so-called laterite ore such as limonite ore and saprolite ore is mainly used. The nickel content of the laterite ore is generally 0.8% by mass to 2.5% by mass, and nickel is contained as a hydroxide or a magnesium silicate (magnesium silicate) mineral. The iron content is 10% by mass to 50% by mass, mainly in the form of trivalent hydroxide (goethite), but some divalent iron is contained in the caustic mineral. .. In addition to such laterite ore, oxide ore containing valuable metals such as nickel, cobalt, manganese, and copper, for example, manganese aneurysm endowed on the deep sea floor, and the like are used.

The method for classifying nickel oxide ore is not particularly limited as long as it can classify the ore based on a desired particle size, and can be performed by, for example, sieving using a general grizzly or a vibrating sieve. Further, the classification point is not particularly limited, and can be determined and adjusted by the processing speed or the like according to the ore type. For example, if the particles having a particle size of less than 45 μm are adjusted to be a classification point that occupies 30% by mass or less of the solid content, the low nickel-containing particles can be separated accurately in a short time.

(2) Separation Step In the sorting step S2, the ore slurry is pretreated prior to the leaching treatment of the ore slurry produced in the ore slurrying step S1. In the present embodiment, in the sorting step S2, the ore slurry obtained through the ore slurrying step S1 is pretreated to separate the high magnesium-containing particles from the ore slurry.

In the present embodiment, the sorting step S2 includes a first separating step S21, a second separating step S22, and a vibrating sieving step S23. In the first separation step S21, the ore slurry obtained through the ore slurrying step S1 is composed of coarse-grained portions having a particle size of less than 45 μm and particles having a particle size of less than 30% by mass in the solid content and particles having a particle size of less than 45 μm. It is separated into fine-grained portions having a higher ratio than the coarse-grained portions, and the fine-grained portions are supplied to the leaching process in the leaching step S4. In the second separation step S22, the coarse grain portion separated in the first separation step S21 is separated into a heavy specific density portion and a light specific gravity portion by a spiral concentrator, and the heavy specific gravity portion is supplied to the leaching process. In the vibrating sieving step S23, the coarse-grained portion separated in the second separation step S22 is separated into an upper sieve and a lower sieve by a vibrating sieve, and the ore slurry under the sieve is supplied to the leaching process in the leaching step S4.

In the wet smelting process of nickel oxide ore, the amount of sulfuric acid used in the leaching process of the leaching step S4 is a metal element contained in nickel oxide ore, which is a raw material ore, and iron, magnesium, manganese, aluminum, etc. other than nickel and cobalt. It is known that it increases due to the presence of the element of. Such a metal element is mainly mixed as a gangue component in a nickel oxide ore slurry (ore slurry) to be subjected to a leachation treatment. Since such gangue components are coarse particles in the ore slurry, for example, coarse particles having a particle size of 45 μm or more, they are separated. As a result, the sulfuric acid used in the leaching process in the leaching step S4 can be saved. Then, the present inventors have found that nickel contained in the coarse particles can be recovered by crushing the coarse particles and adding the coarse particles to the leaching slurry discharged from the leaching step S4.

In addition, magnesium in the gangue component consumes a large amount of sulfuric acid. Therefore, the present inventors have focused on the fact that magnesium content exists as light-density particles, and have developed a separation method focusing on magnesium content. Specifically, it has been found that by separating the light specific density particles, sulfuric acid can be saved while sending most of the nickel content to the leaching step S4. In the present embodiment, by crushing the light specific density particles and adding them to the leachate slurry discharged from the leaching step S4, nickel contained in the light specific gravity particles can also be recovered. At that time, the unreacted sulfuric acid can be neutralized by the nickel contained in the light density particles. Furthermore, in addition to that, magnesium contained in the light density particles can efficiently neutralize unreacted sulfuric acid.

Therefore, in the present embodiment, a large amount of coarse-grained ore of high magnesium-containing particles is separated from the ore slurry to be subjected to the leaching treatment in the leaching step S4, and light specific density particles are further separated from the coarse-grained ore. Pretreatment is performed to carefully select and separate coarse-grained ore from the light-density particles using a vibrating sieve. Then, the light specific density particles are crushed and added to the leaching slurry discharged from the leaching step S4. Hereinafter, each step of the sorting step S2 will be described.

In the first separation step S21, the proportion of the “coarse grain portion” in which the particles having a particle size of less than 45 μm are 30% by mass or less in the solid content and the particles having a particle size of less than 45 μm is coarse in the ore slurry of nickel oxide ore. Separate into "fine grain parts" that are higher than the grain parts. The fine-grained portions obtained by separation are obtained by extracting particles having a particle size of less than 45 μm from the ore slurry obtained in the ore slurrying step S1, and the proportion of the particles having a particle size of less than 45 μm is the ore slurrying. It is higher than the ore slurry obtained in step S1, for example, 65% by mass or more, preferably 89% by mass or more. This fine-grained portion can be used as it is as an ore slurry to be supplied to the leaching process. In the first separation step S21, the coarse particle portion in which the proportion of particles having a particle size of less than 45 μm in the ore slurry is 30% by mass or less and the particles having a particle size of less than 45 μm are used by using a classification separation facility or a specific gravity separation facility. Can be separated into fine-grained portions having a higher ratio of coarse-grained portions.

More specifically, the separation process in the first separation step S21 is performed using at least one of a hydrocyclone and a density separator in 1 to 3 stages. Such a separation treatment using a hydrocyclone or a density separator is preferable because the ore slurry can be accurately separated into underflow and overflow depending on the particle size.

In particular, in this separation treatment, first, the ore slurry is supplied to the hydrocyclone for classification separation (this treatment step is also referred to as “classification separation step”), and then in the classification separation step, classification is performed by the hydrocyclone. It is more preferable to supply the underflow to the density separator for specific gravity separation (this treatment step is also referred to as “specific gravity separation step”).

The reason is that the amount of nickel oxide ore (ore slurry) treated by the hydrometallurgical method is large, and the particles of the ore slurry are, for example, 80% by mass to 95% by mass of the particles. This is because the particle size is as fine as less than 45 μm. Therefore, in the first separation step S21, it is possible to first perform a classification separation treatment with a hydrocyclone, which is suitable for processing a large amount of ore slurry and is suitable for processing when there is a large amount of distribution to the overflow composed of fine-grained portions. preferable. Then, the ore slurry in which the amount to be treated is greatly reduced can be subjected to the specific gravity separation treatment with a density separator suitable for the treatment when the treatment amount is relatively small and the distribution ratio to the underflow and the overflow is almost the same. preferable.

As described above, in the first separation step S21, by performing the separation treatment by the classification separation treatment by the hydrocyclone and the specific gravity separation treatment by the density separator, the coarse particles containing the gangue component in the ore slurry, that is, Low nickel-containing particles can be separated efficiently.

Here, the coarse-grained portion obtained in the first separation step S21 contains particles having a particle size of less than 45 μm as a solid content, and the proportion of particles having a particle size of less than 45 μm is 30% by mass or less of the solid content. do. If it exceeds 30% by mass, the separability in the spiral concentrator deteriorates when it is supplied to the second separation step S22 described later, and many particles having a particle size of less than 45 μm are contained in the light specific gravity portion obtained by the specific gravity separation. It will remain. Then, in the vibrating sieve step S23, which is the next step, the remaining particles having a particle size of less than 45 μm adhere to the coarse particles, and together with the coarse particles, move onto the sieve of the vibrating sieve and are removed.

On the other hand, the smaller the proportion of particles having a particle size of less than 45 μm in the ore supplied to the vibrating sieve, the easier it is for the coarse-grained high-magnesium-containing particles to be mixed in the fine-grained portion from which the coarse-grained portion was separated in the first separation step S21. .. For example, when the proportion of particles having a particle size of less than 45 μm is 10% by mass, coarse particles containing high magnesium may be slightly mixed in the fine particles. On the other hand, at 30% by mass, coarse particles containing high magnesium are hardly found in the fine particles. Therefore, in the present embodiment, the threshold value in the first separation step S21 is suppressed to 30% by mass or less even when the solid content contains 10% by mass or more of particles having a particle size of less than 45 μm in the coarse grain portion of the ore slurry. I am doing it.

In the second separation step S22, the coarse-grained portion having a particle size of less than 45 μm in the ore slurry separated in the first separation step S21 of 30% by mass or less is supplied to the spiral concentrator to supply the coarse-grained portion. It is separated into heavy specific density particles (also referred to as "heavy specific gravity portion") having a larger specific gravity than the solid content and light specific gravity particles (also referred to as "light specific gravity portion") having a smaller specific gravity. The weight specific gravity portion obtained by separation becomes an ore slurry to be supplied to the leaching process.

Specifically, in the second separation step S22, in order to selectively separate the portion where the contained nickel is easily leached from the gangue, the spiral concentrator is used by utilizing the fact that the specific gravity of this portion is small. Perform specific gravity separation. In the spiral concentrator, magnesium can be selectively concentrated on the light density part side by setting the outlet width for collecting the heavy density part to 3 to 12 times the outlet width for collecting the light density part. can. The specific gravity at that time is in the range of 4.0 to 5.0 in the heavy specific gravity portion and 2.7 to 3.7 in the light specific gravity portion.

Comparing the heavy specific gravity part and the light specific weight part obtained in the second separation step S22, the heavy specific weight part has less nickel. The light specific density portion is added to the leaching slurry discharged from the leaching step S4 instead of the leaching step S4 after undergoing several steps to suppress the consumption of acid in the leaching step S4 by magnesium and have a light specific density. Nickel contained in the part can be recovered.

In the vibrating sieve step S23, the ore slurry of the light specific density portion obtained in the second separation step S22 is separated into an upper sieve and a lower sieve using a vibrating sieve. The ore slurry (under the sieve) distributed under the sieve in the vibrating sieving step S23 is supplied to the leaching process in the leaching step S4, and the particles larger than the sieve distributed on the sieve (on the sieve) are subsequently pulverized. The pulverized particles supplied to the pulverization treatment in S9 and obtained in the pulverization treatment are added to the sulfate-acidic leaching slurry discharged from the leaching step S4, and nickel is leached and recovered in the liquid by residual sulfuric acid.

The opening of the vibrating sieve used for the vibrating sieve treatment is not particularly limited, but is preferably about 300 μm to 500 μm. If the opening of the vibrating sieve is less than 300 μm, the proportion of ore grains remaining on the sieve increases, and there is a possibility that a large amount of fine particles having a low magnesium content will remain on the sieve by adhering to the ore grains. There is. On the other hand, if the opening of the vibrating sieve exceeds 500 μm, ore particles, which are high magnesium-containing particles, may be mixed under the sieve. Therefore, in the present embodiment, by configuring the vibrating sieve so that the mesh size is 300 μm or more and 500 μm or less, low magnesium-containing particles remain on the sieve and high magnesium-containing particles are mixed under the sieve. Since the increase can be suppressed, the recovery rate of nickel will be further improved.

As described above, in the present embodiment, the ore grains of the high magnesium-containing particles can be efficiently separated and the ore grains can be dehydrated by performing the treatment with the vibrating sieve. Since these ore grains are larger than the sieve mesh, the reaction efficiency can be improved at once in a short time by subjecting them to pulverization. Further, since the ore grains are dehydrated, a dry mill can be used in the crushing step S9. Instead of the dry mill, a wet mill can be used by adding water.

As described above, in the sorting step S2 according to the present embodiment, the first separation step S21, the second separation step S22, and the vibrating sieving step are used for the ore slurry supplied to the leaching process of the hydrometallurgical method of nickel oxide ore. It has three steps of S23. Therefore, the gangue components such as iron, magnesium, manganese, and aluminum can be efficiently separated on the sieve of the vibrating sieve obtained through the vibrating sieve step S23. In particular, by separating the high magnesium-containing particles from the ore slurry to be leached, the sulfuric acid required for nickel leaching is not consumed by magnesium or the like, so that the amount of sulfuric acid used in the leaching step S4 can be reliably reduced. ..

Further, since the consumption of sulfuric acid is reduced and the concentration can be maintained high, the low magnesium-containing particles can be rapidly leached out and recovered in the leaching step S4. Further, in the present embodiment, since the high magnesium-containing particles separated on the sieve with a vibrating sieve are pulverized in the pulverization step S9 and added to the leachate slurry, a small amount of nickel contained in the high magnesium-containing particles can be recovered. , Nickel recovery rate is further improved.

In the sorting step S2, the first separation step S21, the second separation step S22, and the vibrating sieving step S23 can be arranged in any order. The first separation step S21 is often performed before the second separation step S22, whereby the amount of coarse-grained portions sent to the second separation step S22 can be reduced compared to the amount of ore slurry coming from the ore slurrying step S1. can. In particular, in the first separation step S21, if an apparatus having excellent processing capacity such as a hydrocyclone is used, it is possible to suppress the equipment cost of the first separation step S21 while suppressing the equipment cost of the second separation step S22. Become. Further, the second separation step S22 is often performed before the vibrating sieve step S23, whereby the amount of ore to be processed in the vibrating sieve step S23 is reduced, the burden on the vibrating sieve is reduced, and the vibrating sieve is used. It becomes difficult to clog.

(3) Ore Slurry Concentration Step In the ore slurry concentrating step S3, the ore slurry containing the fine-grained portion separated in the first separation step S21 in the above-mentioned sorting step S2 and the weight specific gravity portion separated in the second separation step S22. The ore slurry and the ore slurry containing the ore particles under the sieving separated in the vibrating sieving step S23 are charged into a solid-liquid separation device, and the water contained in the ore slurry is separated and removed to concentrate the ore components. And obtain a concentrated ore slurry. This concentrated ore slurry becomes an ore slurry to be subjected to the leaching process in the leaching step S4.

Specifically, in the ore slurry concentration step S3, for example, each ore slurry is charged into a solid-liquid separation device such as a thickener, the solid component is settled and taken out from the lower part of the device, while the water content becomes the supernatant. Performs solid-liquid separation that overflows from the top of the device. By this solid-liquid separation treatment, the water content in the ore slurry is reduced and the ore component in the slurry is concentrated to obtain, for example, an ore slurry having a solid content concentration of about 40% by mass. The fine particles separated in the first separation step S21, the heavy specific gravity part separated in the second separation step S22, and the ore particles under the sieve separated in the vibrating sieving step S23 are mixed in advance and then put into a solid-liquid separation device. It is possible to charge, but as another method, prepare a dedicated solid-liquid separation device for each and charge it there, or charge the same solid-liquid separation device with a time lag. May be good.

As described above, the ore slurry formation step S1, the separation step S2 including the first separation step S21, the second separation step S22, and the vibration sieving step S23, and the ore slurry concentration step S3 will be described later. It is possible to produce an ore slurry to be subjected to the leaching process in the leaching step S4, and a method including these steps can be defined as a method for producing the ore slurry.

(4) Leaching Step In the leaching step S4, the produced ore slurry is leached using a high-pressure acid leaching method using, for example, a pressure vessel such as an autoclave or a heat insulating vessel. Specifically, sulfuric acid is added to an ore slurry containing nickel oxide ore as a raw material, and the ore slurry is stirred while pressurizing under high temperature conditions of 220 ° C to 280 ° C, and leachate consisting of a leachate and a leachate residue is leached out. Generate a slurry. That is, in the leaching step S4, sulfuric acid is added to the produced ore slurry and the leaching treatment is performed under high temperature and high pressure.

In the leaching treatment in the leaching step S4, a leaching reaction represented by the following formulas (i) to (iii) and a high-temperature thermal hydrolysis reaction represented by the following formulas (iv) and (v) occur, and nickel, cobalt and the like are produced. Leaching as sulfate and immobilization of leached iron sulfate as hematite are performed.

・ Leaching reaction Ma _{/ 2} O + H ₂ SO ₄ → Ma _{/ 2} SO ₄ + H ₂ O ・ ・ ・ (i)
(Note that M in the formula represents Ni, Co, Fe, Zn, Cu, Mg, Cr, Mn, etc., and a represents a valence).
2Fe (OH) ₃ + 3H ₂ SO ₄ → Fe ₂ (SO ₄ ) ₃ + 6H ₂ O ・ ・ ・ (ii)
FeO + H ₂ SO ₄ → FeSO ₄ + H ₂ O ・ ・ ・ (iii)
・ High temperature thermal hydrolysis reaction 2FeSO ₄ + H ₂ SO ₄ + 1 / 2O ₂ → Fe ₂ (SO ₄ ) ₃ + H ₂ O ・ ・ ・ (iv)
Fe ₂ (SO ₄ ) ₃ + 3H ₂ O → Fe ₂ O ₃ + 3H ₂ SO ₄ ... (v)

In addition to nickel and cobalt, nickel oxide ore also contains impurities such as iron, magnesium, manganese, and aluminum, and these impurities are also leached out by sulfuric acid, and sulfuric acid is consumed as the leaching occurs. Therefore, in addition to the sulfuric acid consumed by the leaching of nickel and cobalt, the sulfuric acid consumed by the leaching of impurities is also required. Regarding the consumption of sulfuric acid due to impurities, in the present embodiment, the ore slurry to be subjected to the leaching treatment in the leaching step S4 is subjected to a specific pretreatment in the above-mentioned sorting step S2, so that magnesium and the like contained in the ore slurry are applied. Impurity concentration can be reduced. Therefore, since the consumption of sulfuric acid due to the gangue component which is an impurity such as magnesium in the leaching step S4 is suppressed, the amount of sulfuric acid added for the leaching treatment can be suppressed while more effectively suppressing the decrease in the actual yield of nickel or the like. It can be effectively reduced.

In addition, the nickel grade and cobalt grade of nickel oxide ore are low, as can be seen from the fact that, for example, dry ore containing about 1% by mass of Ni and about 0.1% by mass of Co is distributed, so that the reaction rate is low. slow. Therefore, in order to increase the reaction rate, sulfuric acid is added in excess of the equivalent amount including the amount of impurities to carry out the leaching reaction at a high concentration. Here, in the present embodiment, the ore slurry to be subjected to the leaching treatment in the leaching step S4 is subjected to a specific pretreatment in the above-mentioned sorting step S2, so that the nickel concentration contained in the ore slurry is improved. Can be done. By reacting a high concentration of sulfuric acid with a high concentration of nickel, the reaction rate is synergistically improved. Therefore, with the same amount of sulfuric acid added, nickel can be leached in a short time, and the amount of sulfuric acid added can be kept small even though the same amount of nickel is leached.

Further, the sulfuric acid remaining unreacted in the leaching step S4 can be effectively utilized by using it for leaching the high magnesium-containing particles separated in the sorting step S2. At that time, the leaching step S4 can be performed in a short time by increasing the amount of sulfuric acid added in the leaching step S4 in anticipation of using the high magnesium-containing particles separated in the sorting step S2 for leaching. The high magnesium-containing particles separated in the sorting step S2 are treated in the pulverization step S9 described later before being mixed with the leached slurry containing sulfuric acid remaining unreacted in the leaching step S4 to enhance the reactivity. Can be enhanced.

Since the high magnesium-containing particles separated in the sorting step S2 consume unreacted sulfuric acid by leaching magnesium or the like, the acidity of the leached slurry weakens, and the particles are used for neutralizing the leachate in the neutralization step S6 described later. It is possible to save the Japanese agent and the neutralizing agent used for neutralizing the leachate residue in the final neutralization step S8. In other words, the high magnesium-containing particles separated in the sorting step S2 can be used as a nickel source and a neutralizing agent.

(5) Solid-Liquid Separation Step In the solid-liquid separation step S5, the leachate containing an impurity element together with nickel and cobalt and the leachate residue are separated while washing the leachate slurry obtained through the leachate step S4 in multiple stages. In the solid-liquid separation step S5 of the present embodiment, for example, after mixing the leached slurry with the cleaning liquid, the solid-liquid separation treatment is performed by a solid-liquid separation facility such as a thickener. Specifically, first, the leaching slurry is diluted with a washing liquid, and then the leaching residue in the slurry is concentrated as a sediment of thickener. Thereby, the nickel content adhering to the leachate residue can be reduced according to the degree of dilution thereof. In the solid-liquid separation treatment, for example, an anionic flocculant may be added.

Further, in the solid-liquid separation step S5, it is preferable to perform solid-liquid separation while washing the leaching slurry in multiple stages. As the multi-stage cleaning method, for example, a continuous countercurrent cleaning method in which the cleaning liquid is brought into contact with the countercurrent with respect to the leachate slurry can be 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 improved to 95% or more. The cleaning liquid (cleaning water) used in the solid-liquid separation step S5 is not particularly limited, but it is preferable to use a cleaning liquid (cleaning water) that does not contain nickel and does not affect the process. For example, as the cleaning liquid, preferably, the poor liquid obtained in the sulfide step S7 in the subsequent step can be repeatedly used.

Further, in the present embodiment, the solid-liquid separation step S5 is characterized in that the crushed particles obtained by crushing the high magnesium-containing particles in the crushing step S9 are added to the leaching slurry and then washed in multiple stages. That is, in the present embodiment, in the solid-liquid separation step S5, the high magnesium-containing particles separated on the sieve by the vibrating sieve in the vibrating sieve step S23 are crushed in the crushing step S9 and added to the leachate slurry for multi-stage washing. By solid-liquid separation while doing so, a small amount of nickel contained in the high magnesium-containing particles can be recovered, so that the recovery rate of nickel is further improved.

(6) Neutralization Step In the neutralization step S6, the pH of the leachate separated in the solid-liquid separation step S5 is adjusted to separate the neutralized starch containing an impurity element, and neutralization containing nickel and cobalt is performed. Get the final solution. Specifically, in the neutralization step S6, the pH of the obtained neutralization final solution is 4 or less, preferably 3.0 to 3.5, more preferably 3.1, while suppressing the oxidation of the separated leachate. A neutralizing agent such as calcium carbonate is added to the leachate so as to be ~ 3.2, and a neutralizing final solution and a neutralized starch containing trivalent iron, aluminum, etc. as impurity elements are produced. In the neutralization step S6, impurities are thus removed as a neutralizing starch to generate a neutralizing final solution as a mother liquor for nickel recovery.

(7) Sulfide step In the sulfurization step S7, a sulfurizing agent such as hydrogen sulfide gas is blown into the neutralized final liquid which is a mother liquor for recovering nickel to cause a sulfurization reaction, and sulfurization containing nickel (and cobalt) is caused. It produces a substance (hereinafter, also simply referred to as "nickel sulfide") and a poor liquid. The neutralization final solution, which is the mother liquor for recovering nickel, is a sulfuric acid solution in which the impurity component is reduced from the leachate through the neutralization step S6. The nickel recovery mother liquor may contain several g / L of iron, magnesium, manganese, etc. as impurity components, but these impurity components are less stable as sulfides (recovery). (For nickel and cobalt), it is not contained in the nickel sulfide produced.

The sulfurization treatment in the sulfurization step S7 is carried out in a nickel recovery facility. Nickel recovery equipment includes, for example, a sulfurization reaction tank in which hydrogen sulfide gas or the like is blown into a neutralized final liquid which is a mother liquor to carry out a sulfurization reaction, and a solid-liquid separation tank in which nickel sulfide is separated and recovered from the liquid after the sulfurization reaction. Equipped with. The solid-liquid separation tank is composed of, for example, a thickener or the like, and the nickel sulfide which is a precipitate is separated and recovered from the bottom of the thickener by subjecting the slurry after the sulfurization reaction containing nickel sulfide to a sedimentation separation treatment. do. On the other hand, the aqueous solution component overflows and is recovered as a poor liquid. The recovered poor liquid is a solution having an extremely low concentration of valuable metals such as nickel, and contains impurity elements such as iron, magnesium, and manganese that remain without being sulfided. This poor liquid is transferred to the final neutralization step S8 described later and detoxified.

(8) Final Neutralization Step In the final neutralization step S8, the poor liquid containing impurity elements such as iron, magnesium and manganese discharged in the sulfide step S7 is adjusted to a predetermined pH range satisfying the discharge standard. Detoxify by neutralization. In this final neutralization step S8, the leaching residue discharged from the solid-liquid separation treatment in the solid-liquid separation step S5 can also be treated.

The method of detoxification treatment in the final neutralization step S8, that is, the method of adjusting the 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 can be adjusted to a predetermined range.

In the final neutralization treatment in the final neutralization step S8, a first-stage neutralization treatment using limestone as a neutralizing agent (first final neutralization step S81) and a second-stage neutralization treatment using slaked lime as a neutralizing agent are performed. A stepwise neutralization treatment including a neutralization treatment (second final neutralization step S82) can be performed. By performing the stepwise neutralization treatment in this way, an efficient and effective neutralization treatment can be performed.

Specifically, in the first final neutralization step S81, the poor liquid discharged and recovered from the sulfide step S7 and the leachate residue separated in the solid-liquid separation step S5 are charged into the neutralization treatment tank, and the limestone slurry is added. And stir. In this first final neutralization step S81, the pH of the solution to be treated such as a poor liquid is adjusted to 4 to 5 by adding a limestone slurry.

Next, in the second final neutralization step S82, 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 final neutralization step S82, the pH of the solution to be treated is raised to 8 to 9 by adding the slaked lime slurry.

By performing such a two-step neutralization treatment, a neutralization treatment residue is generated and stored in a tailing dam (tailing residue). On the other hand, the solution after the neutralization treatment meets the emission standard and is discharged to the outside of the system.

Here, in the treatment in the final neutralization step, the amount of the neutralizing agent such as slaked lime is determined according to the amount of impurity element ions such as magnesium ion and manganese ion remaining in the poor liquid. In the present embodiment, the ore slurry to be subjected to the leaching treatment in the leaching step S4 is subjected to a specific pretreatment in the above-mentioned sorting step S2, so that magnesium, manganese, etc. contained in the ore slurry can be obtained. Impurity elements can be reduced. Thereby, the concentration of these elements contained in the poor liquid can be reduced, and the amount of the neutralizing agent used for the neutralization treatment in the final neutralization step S8 can be effectively reduced.

(9) Crushing Step In the crushing step S9, the high magnesium-containing particles separated in the sorting step S2 are crushed. As a result of diligent studies to achieve the above-mentioned object, the present inventors have obtained high magnesium-containing particles in the nickel oxide ore to be subjected to the leaching step S4, that is, coarse-grained ore by a two-step specific gravity separation method. It was found that nickel can be recovered from the high magnesium-containing particles without increasing the amount of sulfuric acid used by crushing the high magnesium-containing particles separated by the vibrating sieve and adding them to the leaching slurry discharged from the leaching step S4. , The present invention has been completed.

In the pulverization step S9, the high magnesium-containing particles separated in the separation step S2 are pulverized so that the particle size of the 80% by mass particles is less than 100 μm. As a result, the contact efficiency with the pulverized particles is increased, so that nickel contained in the high magnesium-containing particles is leached out and the sulfuric acid remaining in the leached slurry is neutralized reliably, and nickel is suppressed while suppressing the amount of the neutralizing agent used. It will be possible to further increase the amount of recovery. A known crushing device such as a stone mill, a ball mill, or a tower mill can be used for crushing in the crushing step S9.

Next, a hydrometallurgical method for nickel oxide ore according to an embodiment of the present invention will be described in more detail with reference to Examples. The present invention is not limited to the embodiment.

(Example 1)
In Example 1, a nickel oxide ore having the composition shown in Table 1 below is mixed with water to form a slurry (ore slurrying step), and the solid content is 60 t / to a hydrocyclone (manufactured by Salter Cyclone, SC1030-P type). The underflow from the hydrocyclone was supplied to a density separator (manufactured by CFS Co., 6 × 6 type) and subjected to specific gravity separation treatment after being supplied at a flow rate of h and subjected to classification separation treatment. The process of these separation processes is referred to as a first separation step. By the separation treatment in this first separation step, an ore slurry (coarse grain portion) in which the content of particles having a particle size of less than 45 μm in the underflow solid content of the density separator was 25% by mass was obtained.

Next, the coarse-grained ore slurry separated through the first separation step is added with water so as to have a solid content concentration of 20% by mass, and then supplied to a spiral concentrator (manufactured by Autotech) for specific gravity separation. To obtain an ore slurry containing a solid content having a nickel grade of 0.86% by mass and a magnesium grade of 5.5% by mass as a light specific gravity portion. The process of this separation process is referred to as a second separation step.

Next, the separated ore slurry having a light specific density portion was supplied to a vibrating sieve (manufactured by Sizetech Co., Ltd., VDS27-6 type) equipped with a sieve having an opening of 300 μm to perform a sieving process. The step of this sieving process is referred to as a vibration sieving step. By this vibrating sieve, solid content of nickel grade 1.1% by mass and magnesium grade 7.8% by mass, that is, high magnesium-containing particles were obtained on the sieve. On the other hand, the ore slurry under the sieve of the vibrating sieve in the vibrating sieve step, the ore slurry of the fine-grained portion separated in the first separation step (each overflow), and the weight specific gravity portion separated in the second separation step. The ore slurry was supplied to the leaching step after performing the ore slurry concentration step with a thickener. The high magnesium-containing particles recovered on the sieve in the vibrating sieve step are crushed by a crushing tower mill (KW-700MS type manufactured by NIPPON EIRICH), and water is added so as to form a slurry having a solid content concentration of 30% by mass. Then, it was added to the sulfuric acid-acidic leaching slurry discharged from the autoclave in the leaching step to obtain a mixed slurry.

At this time, 92% of the nickel in the ore supplied to the ore slurrying step was leached and recovered in the liquid of the mixed slurry. The amount of sulfuric acid consumed in the leaching step was 278 kg / ton of dry ore. In addition, the slaked lime consumption in the final neutralization step was 44 kg / ton of dry ore.

(Example 2)
The same operation as in Example 1 was performed except that the distribution ratios of the underflow and overflow of the density separator were changed. In the first separation step, an ore slurry (coarse grain portion) in which the content of particles having a particle size of less than 45 μm in the underflow solid content of the density separator was 30% by mass was obtained.

Then, as the second separation step, the obtained ore slurry of the coarse grain portion is supplied to the spiral concentrator at a solid content concentration of 20% by mass, and the nickel grade is 1.1% by mass and the magnesium grade is 5. An ore slurry containing 6% by mass of solid content was obtained.

Further, as a vibrating sieve step, the obtained ore slurry having a light specific gravity portion was supplied to a vibrating sieve provided with a sieve having an opening of 300 μm to perform a sieving process. By this sieving, solid content having a nickel grade of 1.1% by mass and a magnesium grade of 7.5% by mass, that is, high magnesium-containing particles were obtained on the sieve. On the other hand, the ore slurry under the sieve of the vibrating sieve in the vibrating sieve step, the ore slurry of the fine-grained portion separated in the first separation step (each overflow), and the weight specific gravity portion separated in the second separation step. The ore slurry was supplied to the leaching step after performing the ore slurry concentration step with a thickener. The high magnesium-containing particles recovered on the sieve in the vibrating sieve step are crushed by a crushing tower mill (KW-700MS type manufactured by NIPPON EIRICH), and water is added so as to form a slurry having a solid content concentration of 30% by mass. Then, it was added to the sulfuric acid-acidic leaching slurry discharged from the autoclave in the leaching step to obtain a mixed slurry.

At this time, 92% of the nickel in the ore supplied to the ore slurrying step was leached and recovered in the liquid of the mixed slurry. The amount of sulfuric acid consumed in the leaching step was 278 kg / ton of dry ore. In addition, the slaked lime consumption in the final neutralization step was 44 kg / ton of dry ore.

(Comparative Example 1)
The same operation as in Example 1 was carried out except that the solid content on the sieve obtained by the vibrating sieve was discharged out of the process instead of being pulverized and the pulverized particle slurry was not added to the leaching slurry. A solid content having a nickel grade of 1.1% by mass and a magnesium grade of 7.8% by mass was obtained on the sieve of the vibrating sieve. The ore slurry under the sieve of the vibrating sieve in the vibrating sieving step, the ore slurry of the fine-grained portion separated in the first separation step (each overflow), and the ore slurry of the heavy specific gravity portion separated in the second separation step are After performing the ore slurry concentration step with a thickener, it was supplied to the leaching step.

At this time, 88% of the nickel in the ore supplied to the ore slurrying step was leached and recovered in the liquid of the leached slurry. Sulfuric acid consumption in the leaching process was 278 kg / ton of dry ore. The slaked lime consumption in the final neutralization step was 41 kg / ton of dry ore. As described above, in Comparative Example 1, although the amount of sulfuric acid used in the leaching step and the amount of slaked lime used in the final neutralization step could be reduced, the nickel recovery rate was lowered.

(Comparative Example 2)
The same operation as in Example 2 was carried out except that the solid content on the sieve obtained by the vibrating sieve was discharged out of the process instead of being pulverized and the pulverized particle slurry was not added to the leaching slurry. A solid content having a nickel grade of 1.1% by mass and a magnesium grade of 7.5% by mass was obtained on the sieve of the vibrating sieve. The ore slurry under the sieving of the vibrating sieve in the vibrating sieving step, the ore slurry of the fine-grained portion separated in the first separation step (each overflow), and the ore slurry of the heavy specific gravity portion separated in the second separation step are , The ore slurry was concentrated by a thickener and then supplied to the leaching step in which the ore was leached.

At this time, 88% of the nickel in the ore supplied to the ore slurrying step was leached and recovered in the liquid of the leached slurry. Sulfuric acid consumption in the leaching process was 278 kg / ton of dry ore. The slaked lime consumption in the final neutralization step was 41 kg / ton of dry ore. As described above, in Comparative Example 2, although the amount of sulfuric acid used in the leaching step and the amount of slaked lime used in the final neutralization step could be reduced, the actual nickel yield was lowered.

(Comparative Example 3)
The nickel oxide ore whose composition is shown in Table 1 is made into a slurry, and the ore slurry is supplied to the leaching step without pretreatment (first separation step, second separation step, and vibration sieving step) or pulverization. Leaching treatment was performed. At this time, 92% of the nickel in the ore supplied to the ore slurrying step was leached and recovered in the liquid of the leached slurry. Sulfuric acid consumption in the leaching step was 282 kg / ton of dry ore. The slaked lime consumption in the final neutralization step was 44 kg / ton of dry ore. As described above, in Comparative Example 3, the amount of sulfuric acid used in the leaching step and the amount of slaked lime used in the final neutralization step increased.

Regarding the solid content of the ore slurry supplied to the spiral concentrator and the vibrating sieve in the operations of Examples 1 and 2 and Comparative Examples 1 to 2 described above, and the recovered particles recovered on the sieve by the treatment with the vibrating sieve, nickel and The grade of magnesium and the content and flow rate of particles smaller than 45 μm are summarized in Table 2 below.

In addition, the components and flow rate of the solid content of the slurry supplied to the leaching step in the operations of Examples 1 and 2 and Comparative Examples 1 to 2 described above, the amount of sulfuric acid consumed in the leaching step, and the amount of slaked lime consumed in the final neutralization step. , And the nickel recovery rate are summarized in Table 3 below.

As shown in Table 3, when Examples 1 and 2 are compared with Comparative Examples 1 and 2, the high magnesium-containing particles recovered on the vibrating sieve are crushed and added to the leaching slurry to obtain a leaching slurry (mixing). It was found that 4% more nickel could be recovered in the liquid of the slurry).

Further, as shown in Table 3, when Examples 1 and 2 are compared with Comparative Example 3, the high magnesium-containing particles recovered on the vibrating sieve are crushed and added to the leaching slurry to obtain a leaching slurry (mixing). After recovering the same amount of nickel in the liquid of the slurry), it was found that the acid consumption could be suppressed to a low value of 4 kg / dry ore ton.

By crushing the high magnesium-containing particles recovered on the vibrating sieve and adding them to the leachate slurry in this way, the acid remaining in the leachate slurry and the nickel contained in a trace amount in the high magnesium-containing particles are effectively utilized. Ru. As a result, it was found that the amount of sulfuric acid used can be suppressed while reducing the amount of high magnesium-containing particles discarded as residual soil and maintaining the nickel recovery rate.

Although one embodiment of the present invention and each embodiment have been described in detail as described above, those skilled in the art will be aware that many modifications that do not substantially deviate from the new matters and effects of the present invention are possible. , Will be easy to understand. Therefore, all such modifications are included in the scope of the present invention.

For example, a term described at least once in a specification or drawing with a different term in a broader or synonymous manner may be replaced by that different term anywhere in the specification or drawing. Further, the operation of the wet smelting method for nickel oxide ore is not limited to that described in one embodiment of the present invention and each embodiment, and various modifications can be carried out.

S1 ore slurry formation step, S2 separation step, S3 ore slurry concentration step, S4 leaching step, S5 solid-liquid separation step, S6 neutralization step, S7 sulphurization step, S8 final neutralization step, S9 crushing step, S21 first separation step. , S22 2nd separation step, S23 vibrating sieve step, S81 1st final neutralization step, S82 2nd final neutralization step

Claims (1)

It is a hydrometallurgical method for nickel oxide ore that recovers nickel by leaching nickel from nickel oxide ore using the high-pressure acid leaching method.
The ore slurrying step of slurrying the nickel oxide ore and
In the ore slurry obtained through the ore slurrying step, the proportion of particles having a particle size of less than 45 μm is 10% by mass or more and 30% by mass or less, and the proportion of particles having a particle size of less than 45 μm is the coarse particle portion. The first separation step of separating into higher fine particles and supplying the fine particles to the leaching process.
The coarse-grained portion separated in the first separation step is separated into a heavy specific density portion having a specific density of 4.0 to 5.0 and a light specific gravity portion having a specific gravity of 2.7 to 3.7 by a spiral concentrator. In the second separation step of supplying the weight specific gravity portion to the leaching process,
The light specific gravity portion separated in the second separation step is separated into an upper sieve and a lower sieve by a vibrating sieve having an opening of 300 μm or more and 500 μm or less, and the ore slurry under the sieve is supplied to the leaching process. Process and
It has a pulverization step of pulverizing the high magnesium-containing particles recovered on the sieve so that the particle size of 80% by mass of the particles is less than 100 μm.
The first separation step is
A classification separation step of supplying the ore slurry to a hydrocyclone for classification separation,
In the classification separation step, the underflow classified by the hydrocyclone is supplied to the density separator to perform specific gravity separation.
The underflow after the specific gravity separation step is referred to as the coarse grain portion, and the overflow after the classification separation step and the overflow after the specific gravity separation step are referred to as the fine grain portion.
A method for hydrometallurgical nickel oxide ore, which comprises adding the high magnesium-containing particles crushed in the crushing step to a sulfuric acid-acidic leaching slurry discharged in the leaching process.

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