JP2018193588A - Method for leaching sulfide - Google Patents

Abstract

To provide a method for leaching a sulfide that can suppress costs by inhibiting sulfur from being completely oxidized in a reaction vessel into which a sulfide slurry including a sulfide containing nickel or cobalt has been supplied.SOLUTION: The method for leaching a sulfide comprises supplying an oxygen-containing gas into a reaction vessel into which a sulfide slurry prepared by mixing a sulfide containing at least one of nickel and cobalt with a sulfuric acid acidic solution containing an iron ion has been supplied while controlling a temperature of the sulfide slurry to 80°C or more to less than 115°C to thereby produce a liquid after leaching and sulfur under conditions that an oxygen partial pressure in the reaction vessel is more than 0 MPa to 1 MPa or less. By the method, sulfur can be inhibited from being completely oxidized in leaching nickel and the like from a sulfide. Consequently, the generation of sulfuric acid can be suppressed and therefore, the amount of sulfuric acid to be treated can be reduced and the cost required for treatment of sulfuric acid can be suppressed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sulfide leaching method. More specifically, the present invention relates to a sulfide leaching method in which nickel or the like contained in a predetermined sulfide is leached into a sulfuric acid acidic solution, and at the same time, sulfur is prevented from being completely oxidized.

  As part of the method of refining nickel and cobalt, HPAL (High) is used in which nickel oxide ore is put in a reaction solution such as an autoclave together with a sulfuric acid solution, and nickel and cobalt contained in the nickel oxide ore are leached into the sulfuric acid solution at high temperature and high pressure. There is a Pressure Acid Leach) process. The leachate obtained by this HPAL process is a sulfuric acid acidic solution containing nickel and cobalt. This leachate is then neutralized and added to the neutralized starch, where impurities are precipitated and separated, and then the neutralized solution is added with a sulfiding agent to form a mixed sulfide (hereinafter referred to as “Mixed Sulfide”). , Sometimes referred to herein as “MS”). Then, the liquid after sulfiding and MS are separated into solid and liquid, and MS is recovered.

  When an acid such as sulfuric acid or hydrochloric acid is added to the recovered MS and leached, a sulfate solution or chloride solution of nickel or cobalt (hereinafter sometimes referred to as “post-leaching solution” in this specification). Nickel metal can be obtained by adding a neutralizing agent to these solutions, separating impurities using means such as solvent extraction, and then subjecting an acidic solution containing nickel or cobalt to a method such as electrowinning. And cobalt metal is refined and these are traded as high purity metal.

  If a chloride solution is used in the leaching step by adding the acid, chlorine gas is generated from the anode in the subsequent electrowinning. Therefore, the equipment must be able to withstand this chlorine gas. However, in the electrowinning using a sulfate solution, oxygen is generated from the anode, so there is no need for special equipment as compared with the case of using a chloride solution, thereby reducing the manufacturing cost. In addition, it has the effect of being easy to manufacture.

  As a method of leaching MS with sulfuric acid, which constitutes a part of the above-described method for refining nickel and cobalt, there is a method disclosed in Patent Document 1, for example.

In the method of Patent Document 1, as shown in Equation 1, a sulfide (here, nickel sulfide) is made into a slurry in a solution, and a sulfate (here, nickel sulfate) is obtained using oxygen. By setting the reaction temperature during leaching to 110 to 165 ° C. and the oxygen partial pressure in the reaction vessel to the range of 0.05 to 2.0 MPa, sulfide ions contained in the sulfide in the slurry (S ²⁻ ) The whole amount is oxidized to sulfate ion (SO ₄ ²⁻ ).

(Equation 1)
NiS + 2O ₂ → NiSO ₄

  However, when the so-called “complete oxidation leaching method” in which the sulfide is completely oxidized with oxygen is used, there is a problem in that sulfur cannot be balanced and the cost required for the treatment of the generated sulfuric acid increases.

  The point that “the sulfur balance is lost” will be specifically described below. When nickel metal is recovered by electrowinning using the acidic solution containing nickel sulfate obtained by the above-described complete oxidation leaching method as the electrolytic solution as described above, as shown in Equation 2, nickel is on the cathode. Then, sulfuric acid is generated in the electrolytic solution. If the produced sulfuric acid is left as it is, the sulfuric acid concentration of the electrolytic solution increases beyond the allowable limit with the electrodeposition of nickel, and it becomes impossible to operate at the end. For this reason, the work which extracts a part of electrolyte solution, adds neutralizing agents, such as slaked lime, neutralizes sulfuric acid, and disposes of electrolyte solution is needed. As a result, there is a cost for treating the neutralizing agent used in the treatment and the generated starch.

(Equation 2)
NiSO ₄ + 2H ⁺ + 2e → Ni ⁰ + H ₂ SO ₄

  Here, in a series of methods for refining nickel and cobalt, as described above, sulfuric acid is used in the step of leaching nickel from nickel oxide ore or MS. It is also conceivable to use the sulfuric acid produced in Equation 2 in this leaching step. However, if all the sulfur contained in the sulfide is oxidized to sulfate ions, the amount of sulfuric acid produced will be greater than the amount required for the above leaching, and some sulfuric acid must be neutralized and disposed of. There is. In addition, a sulfurizing agent such as hydrogen sulfide used for precipitating MS is produced from a single sulfur, and at the upstream of the process, the sulfur is disposed of by neutralizing sulfuric acid downstream of the purification process. There is a problem that the process itself is not efficient, such as adding new sulfur.

  For this reason, the production of nickel solution by the above-described complete oxidation leaching method is compared to obtaining nickel sulfate solution or nickel sulfate crystals used as a material for secondary batteries, for example, rather than being used in a process for obtaining nickel metal with a large production amount. In a process for obtaining nickel metal, there is a problem that it is difficult to expand the use, in particular, it is difficult to reduce the cost.

  Because of the above problems, a process that can efficiently produce nickel and cobalt metals at low cost using MS obtained from nickel oxide ore as a raw material has been desired.

Japanese Examined Patent Publication No. 7-84623

  In view of the above circumstances, the present invention can reduce costs by suppressing sulfur from being completely oxidized in a reaction vessel supplied with a sulfide slurry containing sulfide containing nickel or cobalt. An object is to provide a sulfide leaching method.

The sulfide leaching method according to the first aspect of the present invention is a reaction vessel supplied with a sulfide slurry prepared by mixing a sulfide containing at least one of nickel and cobalt and an acidic sulfuric acid solution containing iron ions. Leaching under the condition that the temperature of the sulfide slurry is 80 ° C. or higher and lower than 115 ° C. and an oxygen-containing gas is supplied into the reaction vessel so that the oxygen partial pressure in the reaction vessel exceeds 0 MPa and is 1 MPa or less. It is characterized by obtaining a post-solution and sulfur.
The sulfide leaching method according to a second aspect of the present invention is the method according to the first aspect, wherein the sulfide is obtained by adding a sulfiding agent to an acidic solution obtained by leaching nickel oxide ore with sulfuric acid. It is characterized by.
The sulfide leaching method of the third invention is characterized in that, in the second invention, the sulfur is repeated as a raw material of the sulfiding agent.
The sulfide leaching method according to a fourth aspect of the present invention is the method according to any one of the first to third aspects, wherein at least one of nickel and cobalt is recovered by electrodeposition from an electrolytic starting solution obtained by separating impurities from the leached solution. The electrolytic final solution is repeated as the sulfuric acid acidic solution.

According to the first invention, it is possible to suppress the complete oxidation of sulfur when leaching nickel or the like from the sulfide by the sulfide leaching method in which the inside of the reaction vessel is set to a predetermined condition. Thereby, since generation | occurrence | production of a sulfuric acid can be suppressed, the process amount of a sulfuric acid can be decreased and the expense concerning the process of a sulfuric acid can be suppressed. Further, by employing this sulfide leaching method, it is possible to reduce the manufacturing cost of nickel metal or the like.
According to the second invention, the sulfide is obtained by adding a sulfiding agent to an acidic solution obtained by leaching nickel oxide ore with sulfuric acid, so that the stable leaching of components. A post-solution and sulfur can be obtained. Thereby, since the stable leaching solution can be provided to the downstream side of the sulfide leaching method of the present application, the downstream process is stabilized.
According to the third invention, the sulfur obtained at the same time as the leaching solution is repeated as a raw material for the sulfiding agent, whereby the amount of new sulfur added to the sulfiding agent to be added can be reduced, and the cost of the process Can be suppressed.
According to the fourth aspect of the invention, by repeating the electrolytic final solution as a sulfuric acid acidic solution, the amount of newly added sulfuric acid acidic solution can be reduced, and the cost for the process can be suppressed.

It is explanatory drawing of the leaching method of the sulfide which concerns on the embodiment of this invention. It is a graph which shows the relationship between Ni leaching rate and S oxidation rate when changing oxygen partial pressure. It is a graph which shows the relationship between Ni leaching rate and S oxidation rate when changing sulfuric acid concentration. It is a graph which shows the relationship between Ni leaching rate when changing the temperature of sulfide slurry, and time.

The sulfide leaching method of the present invention will be described.
The sulfide leaching method of the present invention comprises a sulfide containing a sulfide containing at least one of nickel and cobalt and a sulfuric acid acidic solution containing iron ions in a reaction vessel supplied with the sulfide slurry. The temperature of the slurry is set to 80 ° C. or higher and lower than 115 ° C., and the oxygen-containing gas is supplied into the reaction vessel, so that the oxygen partial pressure in the reaction vessel exceeds 0 MPa and is 1 MPa or less. And get.

  Here, the sulfide containing at least one of nickel and cobalt is a so-called MS obtained by adding a sulfiding agent to an acidic solution obtained by leaching nickel oxide ore with sulfuric acid. It is desirable.

  Moreover, it is desirable to repeat the sulfur obtained simultaneously with the liquid after leaching as a raw material for the sulfiding agent.

  In addition, from the electrolytic starting solution from which impurities were separated from the leached solution, the electrolytic final solution after at least one of nickel and cobalt was recovered by electrodeposition, that is, nickel and cobalt were separated from nickel sulfate and cobalt sulfate to form free sulfuric acid. The regenerated (or by-product) sulfuric acid is preferably used as an acidic sulfuric acid solution and used for leaching MS.

  An embodiment of the sulfide leaching method of the present invention will be described with reference to FIG. 1 and a chemical reaction formula. The sulfide leaching method of the present invention is not limited to this embodiment.

  FIG. 1 shows an explanatory view of a sulfide leaching method according to an embodiment of the present invention. As shown in FIG. 1, in this embodiment, an autoclave is used as a reaction vessel. However, the reaction vessel is not particularly limited to this, and there is no particular problem as long as the sulfide slurry can be processed under high temperature and high pressure.

In this embodiment, the sulfuric acid acidic solution containing iron ions is preferably ferric sulfate. In this embodiment, the chemical reaction formula when MS is leached using sulfuric acid (Equation 3) and ferric sulfate solution (Equation 4) is shown below. At this time, as shown in Equation 3, the generated hydrogen sulfide is converted to sulfur (or sulfide ion (S ²⁻ )) by simple reaction with the reaction shown in Equation 5 due to the presence of ferric sulfate (S ⁰ ). As fixed.
In addition, since ferric sulfate acts as an oxidizing agent and itself is reduced to ferrous sulfate, ferric sulfate can be regenerated by being oxidized again with air or the like and repeatedly used as an oxidizing agent.

(Equation 3)
NiS + H ₂ SO ₄ → NiSO ₄ + H ₂ S

(Equation 4)
NiS + Fe ₂ (SO ₄ ) ₃ → NiSO ₄ + 2FeSO ₄ + S ⁰

(Equation 5)
H ₂ S + Fe ₂ (SO ₄ ) ₃ → 2FeSO ₄ + H ₂ SO ₄ + S ⁰

  In the present specification, the rate at which nickel contained in the sulfide dissolves in the acidic solution as nickel ions is expressed as “Ni leaching rate”, and the rate at which the sulfur contained in the sulfide becomes sulfate ions is expressed as “S”. "Oxidation rate". Here, the “S oxidation rate” is in principle coincident with the rate at which sulfides are oxidized and eluted into the solution. Of course, a higher nickel leaching rate is preferable because a higher nickel recovery rate is preferable. When sulfur is not desired to be eluted as in the present invention, a lower sulfur oxidation rate is preferable.

  In this embodiment, by controlling the partial pressure of oxygen in the reaction vessel, MS and oxygen are consumed by leaching (reduction) while suppressing the reaction so that direct leaching is not caused by the complete oxidation leaching method shown in Equation 1. ) Promotes oxidation of ferrous sulfate (Formula 6) to regenerate ferric sulfate. Thus, this embodiment is a sulfide leaching method that uses MS as a single raw material and suppresses the oxidation of sulfide ions contained in MS to sulfate ions. The sulfide leaching method is nickel or the like. Part of the wet refining process.

(Equation 6)
2FeSO ₄ + H ₂ SO ₄ + 1 / 2O ₂ → Fe ₂ (SO ₄ ) ₃ + H ₂ O

  As described above, most nickel oxide ores are known to contain cobalt together with nickel. However, cobalt takes the same chemical behavior as nickel and uses means such as solvent extraction in the latter stage of the purification process. Need to be separated. Therefore, as another embodiment, the sulfide leaching method according to the present invention can also be used in a cobalt purification method. In that case, in the above chemical reaction formula, what is displayed as Ni can be interpreted by replacing it with Co.

The sulfide leaching method according to the embodiment of the present invention will be described in more detail.
First, MS is added to a sulfate solution to form a slurry, thereby obtaining a sulfide slurry. As shown in FIG. 1, this sulfate solution is either a single solution of ferric sulfate or an electrolytic final solution containing ferric sulfate (hereinafter referred to as “electrolytic poor solution” in this specification). Can be used).

  Next, sulfuric acid is added to the sulfide slurry as necessary, and the slurry is transferred into a closed vessel that can withstand high temperature and high pressure, such as an autoclave, as shown in FIG. 1, and maintained at a predetermined temperature and oxygen partial pressure for reaction. Let

  The concentration of sulfuric acid and ferric sulfate in the slurry is not particularly limited as long as it is acidic, but with respect to the mol amount of valuable metals to be leached such as nickel and cobalt contained in MS. The amount of sulfuric acid is preferably 1 to 2 times equivalent, and the amount of ferric sulfate is preferably 0.25 to 0.5 times equivalent of valuable metals. In the present specification, the symbol “˜” means “above and below”.

  If the sulfuric acid concentration is excessively high, the cost of the neutralizing agent during waste liquid treatment increases. Similarly, if the concentration of ferric sulfate is excessively high, the cost for separating the iron by washing before electrolysis increases, which is not preferable.

The leaching of MS in the sealed container is preferably performed at a temperature lower than 115 ° C. at which elemental sulfur (S ⁰ ) does not melt, and more preferably in the range of 80 ° C. or higher and 105 ° C. or lower. This is because if the reaction temperature is less than 80 ° C., the leaching rate decreases, and if it is 115 ° C. or more, complete oxidation leaching occurs.

  On the other hand, the oxygen partial pressure during leaching is preferably in the range of 0.15 to 1.0 MPa. Even if the oxygen partial pressure exceeds 1.0 MPa, there is no advantage that the leaching reaction proceeds quickly, but rather the complete oxidation leaching shown in the above equation 1 in which oxygen is leached directly from MS is promoted, so that oxidation of sulfur It is not preferable because the rate increases.

  On the other hand, when the oxygen partial pressure is 0 MPa, oxygen does not exist at all and the reaction does not proceed. Therefore, the oxygen partial pressure needs to exceed 0 MPa. However, the oxygen partial pressure of 0.15 MPa or more is preferable because the reaction proceeds efficiently.

Purification process (Impurity removal) for separating impurities such as iron leached together with valuable components such as nickel and cobalt from the leached liquid obtained under the leaching conditions shown above by known means such as neutralization and solvent extraction ), And the obtained solution after purification is placed in an electrolytic cell as an electrolytic starting solution. For example, an insoluble anode and a cathode made of titanium, etc. are charged and electrowinning is performed, and nickel metal is deposited on the cathode. As shown in FIG. 1, nickel metal (E-Ni ^{0 in} FIG. 1) can be recovered.

  Further, as shown in FIG. 1, it is desirable to repeatedly use sulfuric acid in the electrolytic solution produced by the deposition of nickel on the cathode surface, that is, the electrolytic final solution, in the electrolytic bath and use it for MS leaching. At this time, it is desirable to raise the concentration of sulfuric acid in the final electrolytic solution, and to discharge from the electrolytic cell when the concentration of sulfuric acid rises to the allowable upper limit for electrolysis.

  Hereinafter, specific examples of the present invention will be described. The scope of the present invention is not limited to any of the following examples.

<MS adjustment>
Nickel oxide ore is subjected to a known HPAL treatment to obtain a sulfuric acid leachate, neutralized by adding calcium carbonate to the leachate, and impurities are precipitated as neutralized starch and separated from the neutralized solution, Subsequently, hydrogen sulfide gas was blown into the liquid after neutralization, and recovered as MS containing nickel and cobalt.

  Next, the MS was pulverized using a planetary ball mill to obtain an MS pulverized product. Table 1 shows the quality and particle size distribution of the MS pulverized product. The quality of each component was analyzed using ICP emission spectroscopy.

<Example 1>
Using 50 g of the MS pulverized product having the composition shown in Table 1, the reaction was carried out using a sealed container for the reactivity at the ferric sulfate concentration and oxygen partial pressure levels shown in Table 2. A 3.4 L capacity Hastelloy autoclave (manufactured by Nitto Koatsu Co., Ltd.) was used for the sealed container, and a mass flow controller (model name 5850i SERIES) manufactured by BROOKS was used to control the oxygen partial pressure. The controller had a flow rate of 0.5 L / min when the opening was 100%, so the opening was adjusted to about 1% and the oxygen partial pressure was adjusted to 0.15 MPa and maintained.

  The component concentration of the solution for slurrying MS was 0.85 mol / L (50 g / L in terms of nickel concentration), which is the same concentration as the concentration of nickel sulfate in the electrolysis final solution (electrolytic poor solution) of nickel electrowinning. The amount of sulfuric acid added was 0.49 mol / L (48.4 g / L in terms of sulfuric acid concentration), which is almost the same as the molar equivalent of nickel contained in MS.

  Considering that oxidation and reduction are repeated, the addition amount of ferric sulfate is 0.26 mol / L (30 g / L in terms of trivalent iron ion concentration), which is about half the molar equivalent of nickel contained in MS. L), and 0.13 mol / L to be 25% (15 g / L in terms of trivalent iron ion concentration), and 0.04 mol / L (three) considering the load reduction in the liquid purification step before electrolysis It was set to 3 levels of 5 g / L) in terms of iron ion concentration.

  These were put in a vessel made of titanium with a baffle and opened on the upper surface to form a sulfide slurry, and charged into the autoclave described above. Next, the autoclave is sealed, the temperature of the sulfide slurry in the autoclave is raised to 105 ° C., then oxygen gas is sent from the outside of the autoclave, and oxygen in the gas phase part (gap part where no solution is contained) The leaching was continued for 3 hours while controlling the partial pressure. While measuring the internal pressure, an oxygen-containing gas was supplied so that a predetermined partial pressure would be obtained if the oxygen partial pressure decreased due to the reaction.

  After the reaction time, the autoclave lid was opened after cooling to 70 ° C. or less, and the titanium container was taken out. Next, the slurry in the titanium container was mixed with Nutsche and No. 2 in the following manner. Solid-liquid separation was performed using 5C quantitative filter paper. The obtained leaching residue was repulped with pure water to remove the adhering liquid, and then vacuum dried to confirm the weight. Thereafter, the components were separated and the quality of the components of the leaching residue was analyzed using ICP emission spectroscopy.

  The Ni leaching rate and S oxidation rate under each condition shown in Table 2 are shown in Table 2 and FIG. The specific calculation methods for the Ni leaching rate and the S oxidation rate are as shown in Equations 7 and 8.

From Table 2 and FIG. 2 showing the results of this example, the following can be understood.
1) When the temperature of the sulfide slurry is 105 ° C., sulfur can be obtained by lowering the S oxidation rate while leaching nickel, by setting the oxygen partial pressure to more than 0 MPa and not more than 1 MPa.

2) The concentration of ferric sulfate in the slurry is compared at the same oxygen partial pressure (for example, oxygen partial pressure 0.5 MPa, which is a triangular mark in the graph, and oxygen partial pressure 1.0 MPa, which is a circular mark in the graph). When the concentration of ferric sulfate is increased from 0.04 mol / L to 0.13 mol / L, the S oxidation rate can be lowered. In other words, sulfide ions ^{(S 2-)} contained in the MS can be prevented from being oxidized to sulfate ions _(SO ^{4 2-).}

  In addition, when the density | concentration of ferric sulfate was 0.13 mol / L and 0.26 mol / L, the difference of S oxidation rate was not large. However, when the addition amount of ferric sulfate is reduced to a concentration of 0.04 mol / L, the Ni leaching rate is the same while the S oxidation rate is increased. This is because, as MS is leached in the reaction vessel, oxygen has priority over the leaching of MS directly (Formula 1) over the reduction reaction of ferric sulfate to ferrous sulfate (Formula 6). It is thought that it is consumed. For this reason, it is desirable to ensure the addition amount of ferric sulfate is 0.25 equivalent (0.13 mol / L in this example) or more with respect to the molar equivalent of nickel in MS.

3) When the oxygen partial pressure in the reaction vessel is the same ferric sulfate concentration, the nickel leaching rate and the sulfur oxidation rate increase linearly as the oxygen partial pressure increases. That is, when the oxygen partial pressure increases, the S oxidation rate increases, and the tendency of MS sulfur to be leached directly by oxygen increases. From this, it is considered that a lower oxygen partial pressure is preferable, but since it is necessary to obtain a sufficient nickel leaching rate, practically 0.15 MPa is set to the lower limit, preferably about 1.0 MPa. An oxygen partial pressure is required.

<Example 2>
Using 50 g of the same MS ground product as in Example 1, the effect of the amount of sulfuric acid added to the solution containing the MS ground product was confirmed. The oxygen partial pressure at this time is as shown in Table 3. In consideration of the durability of the reaction vessel, the upper limit of sulfuric acid was 0.92 mol / L (90 g / L in terms of sulfuric acid concentration), and compared with 0.49 mol / L added in Example 1. Other processing conditions and processing methods are the same as those described in the first embodiment. The Ni leaching rate and S oxidation rate at this time are shown in Table 3 and FIG.

From Table 3 showing the results of this example and FIG.
1) Similar to Example 1, sulfur can be obtained by reducing the S oxidation rate by setting the temperature of the sulfide slurry to 105 ° C. and the oxygen partial pressure to more than 0 MPa and not more than 1 MPa.

2) It can be seen from Table 3 and FIG. 3 that when the amount of sulfuric acid added is increased, that is, the sulfuric acid concentration is increased, the Ni leaching rate becomes substantially the same, but the S oxidation rate can be reduced. This means that the sulfide ions (S ²⁻ ) could be suppressed from becoming sulfate ions (SO ₄ ²⁻ ).

  The suppression of sulfur oxidation due to the increase in the amount of sulfuric acid promotes the leaching of MS shown in Equation 3 with sulfuric acid, and the reduction of sulfuric acid by the fixation of sulfur with ferric sulfate (Equation 5). It is considered that a large amount of ferrous iron was obtained, and a large amount of oxygen was consumed in the reaction (Equation 6) in which this much obtained ferrous sulfate was oxidized to regenerate ferric sulfate.

<Example 3>
In Example 3, the influence of the MS leachability by sulfuric acid on the temperature of the sulfide slurry was investigated.
Four sets of heat-resistant glass separable flasks with baffle plates were prepared, and 1 liter of sulfuric acid solution having a sulfuric acid concentration of 20 g / L (the amount of sulfuric acid was 0.204 mol) was supplied. Each was put in an oil bath while stirring at a rotation speed of 800 rpm, and the temperature of the oil bath was set to 50 ° C., 70 ° C., 80 ° C., and 90 ° C.

  Thereafter, 10 g of MS having the composition shown in Table 1 above was charged in one set (the nickel amount was 0.099 mol) and maintained for 2 hours to carry out the reaction. At the time when 5 minutes, 10 minutes, 20 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes had elapsed after the introduction of MS, 30 mL of the leached solution was sampled.

  The sampled leached solution was No. Filtration was performed using 5C quantitative filter paper, and the nickel concentration of the obtained filtrate was analyzed using ICP emission spectrometry to confirm the amount of nickel elution. The respective Ni leaching rates are shown in Table 4 and FIG.

  From Table 4 and FIG. 4, when the leaching temperatures were 50 ° C. and 70 ° C., the leaching rate did not change greatly over time, but when the temperature was 80 ° C. or higher, the leaching rate tended to improve. This means that the leaching rate of MS to sulfuric acid cannot be sufficiently obtained when the temperature is lower than 80 ° C. For this reason, it is preferable to leach at the temperature exceeding 80 degreeC.

<Example 4>
Ni leaching rate and S oxidation rate were measured at 50 ° C. to 150 ° C. sulfide slurry temperature shown in Table 5 using 50 g of the same MS ground product as in Example 1. At this time, the oxygen partial pressure was 0.15 MPa, the leaching time was 3 hours, and the ferric sulfate concentration was 30 g / L. Other processing conditions and processing methods were the same as those described in Example 1. .

  From Table 5, in the temperature range of 80 to 105 ° C., there is almost no difference between the Ni leaching rate and the S oxidation rate. In contrast, it was confirmed that the Ni leaching rate decreased at 120 ° C., and the S oxidation rate increased at 150 ° C. even though the Ni leaching rate did not increase.

  This is because the elemental sulfur produced in the process of leaching MS with sulfuric acid and ferric sulfate melts at the leaching temperature exceeding the melting point, and the MS surface is covered with sulfur and coated, so that sulfuric acid and ferric sulfate are used. This is thought to be because the leaching of MS by hinders the inhibition, and the leaching of nickel proceeds by complete oxidation leaching accompanied by oxidation of sulfur (Equation 1).

  As described above, from the results of Examples 1 to 4 described above, nickel can be leached while suppressing oxidation of sulfur by leaching MS within the condition range of the sulfide leaching method of the present invention. Thereby, nickel metal can be obtained by electrolytically collecting the leached solution containing nickel. In addition, the electrolytic final solution after recovering nickel by electrodeposition is repeatedly used for MS leaching, or the simple sulfur recovered without being oxidized is repeatedly used as a raw material for the sulfiding agent. It has been confirmed that the leaching method has become economical with reduced costs such as sulfiding agents, and can be used to carry out the nickel smelting process while reducing costs.

Claims (4)

In a reaction vessel supplied with a sulfide slurry containing a sulfide containing at least one of nickel and cobalt and an acidic sulfuric acid solution containing iron ions,
The temperature of the sulfide slurry is 80 ° C. or higher and lower than 115 ° C.,
By supplying an oxygen-containing gas into the reaction vessel, the oxygen partial pressure in the reaction vessel is more than 0 MPa and 1 MPa or less,
To obtain liquid and sulfur after leaching,
A sulfide leaching method characterized by the above. The sulfide is
Nickel oxide ore into an acidic solution obtained by leaching with sulfuric acid,
Obtained by adding a sulfurizing agent,
The sulfide leaching method according to claim 1. Repeating the sulfur as a raw material for the sulfurizing agent,
The sulfide leaching method according to claim 2. The electrolytic end solution after recovering at least one of nickel and cobalt by electrodeposition from the electrolytic start solution from which impurities have been separated from the post-leaching solution is repeated as the sulfuric acid acidic solution.
The sulfide leaching method according to any one of claims 1 to 3, wherein: