JP2008231470A - Method for controlling reaction in sulphidizing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly efficient method for controlling a reaction in a sulphidizing process, which inhibits a produced sulfide from depositing onto the inner surface of a reaction vessel, and stabilizes a nickel concentration at the end point of the reaction in a low level to increase a nickel-collecting rate, in the sulphidizing process of forming a sulfide (B) containing nickel and a barren solution by blowing hydrogen sulfide gas into an aqueous solution (A) of sulfuric acid containing nickel. <P>SOLUTION: In the sulphidizing process of forming the sulfide (B) containing nickel and the barren solution by blowing hydrogen sulfide gas into the aqueous solution (A) of sulfuric acid containing nickel, this reaction-controlling method includes cyclically using the sulfide (B) containing nickel in an amount 4 to 6 times as much as an amount of nickel contained in the aqueous solution (A) of the sulfuric acid, as a seed crystal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reaction control method for a sulfidation step, and more specifically, hydrogen sulfide gas is blown into a sulfuric acid aqueous solution (A) containing nickel and cobalt to form a poor solution with a sulfide (B) containing nickel and cobalt. The present invention relates to a highly efficient sulfidation process reaction control method capable of suppressing the adhesion of the produced sulfide to the inner surface of the reaction vessel and stabilizing the nickel concentration at the reaction end point at a low level and increasing the nickel recovery rate. . In particular, in a hydrometallurgical method based on high-temperature pressure leaching for recovering nickel from nickel oxide ore, it is used as a reaction control method for a sulfurization step of a sulfuric acid aqueous solution containing nickel and cobalt.

Conventionally, in nickel smelting, nickel sulfide ore is dry-smelted to obtain a mat having a nickel quality of about 30% by weight, and thereafter a method for producing electrical nickel by a chlorine leaching-electrolytic extraction method is performed. ing.
In recent years, attention has been focused on a high pressure acid leaching method using sulfuric acid as a wet smelting method of nickel oxide ore. Unlike the conventional dry smelting method, which is a conventional nickel oxide ore smelting method, this method does not include dry processes such as reduction and drying processes, and is a consistent wet process. In addition, the nickel sulfide having an improved nickel quality up to about 50% by weight can be obtained. This nickel sulfide is usually precipitated by purifying the leachate and then blowing hydrogen sulfide gas in the sulfiding step.

  By the way, in the field of nickel hydrometallurgy, in addition to the formation of nickel sulfide, a method of separating and separating impurity elements such as zinc, copper, and iron in a liquid under slight pressure has been performed. However, in the prior art, by setting the reaction temperature of sulfidation to around 100 ° C., the reaction temperature is increased to increase the reaction rate, thereby improving the reaction efficiency. However, the conventional technique has a problem that the produced sulfide is likely to adhere to the inner surface of the reaction vessel, and there is also a problem that the operation cost is high.

As a solution to this, in the high-temperature pressure leaching process of nickel oxide ore (see, for example, Patent Document 1), a sulfide seed crystal is added in the sulfidation step, and the nickel and cobalt mixed sulfide obtained in the sulfidation step is added. It is disclosed that it is repeatedly circulated and used, and the amount of sulfide added is preferably 1 to 3 times the amount of nickel in the liquid.
By the way, in general, in the step of blowing hydrogen sulfide gas into a sulfuric acid aqueous solution containing nickel and cobalt to obtain a sulfide containing nickel, the liquid obtained after the reaction (hereinafter sometimes referred to as a poor liquid) is a trace amount. Contains nickel. Since this poor solution is sent to the final neutralization step after this step and processed, it is difficult to recover the nickel contained in the poor solution. Therefore, reducing the nickel concentration in the poor solution has been an important technical issue in order to increase the nickel recovery rate.

  However, with the above repeated circulation amount, it is difficult to sufficiently suppress the adhesion of the product sulfide to the inner surface of the reaction vessel and it is difficult to sufficiently reduce the nickel concentration in the poor solution. From the above situation, there is a need for a highly efficient reaction control method for the sulfurization process that can stabilize the nickel concentration at the reaction end point at a low level and increase the nickel recovery rate in the sulfurization process.

JP-A-2005-350766 (first page, second page)

  In view of the above-mentioned problems of the prior art, an object of the present invention is to perform a sulfurization process in which a hydrogen sulfide gas is blown into a sulfuric acid aqueous solution (A) containing nickel to form a sulfide and a sulfide containing nickel (B). To provide a highly efficient sulfidation process reaction control method capable of suppressing the adhesion of the generated sulfide to the inner surface of the reaction vessel, stabilizing the nickel concentration at the reaction end point at a low level, and increasing the nickel recovery rate. is there.

  In order to achieve the above object, the inventors of the present invention have conducted extensive research on a sulfurization process in which hydrogen sulfide gas is blown into a sulfuric acid aqueous solution containing nickel to form a sulfide and a sulfide containing nickel. In the sulfidation step, when the sulfide corresponding to a specific nickel amount is circulated and used as a seed crystal for the nickel amount contained in the sulfuric acid aqueous solution, the adhesion of the generated sulfide to the inner surface of the reaction vessel is sufficiently suppressed, The present inventors have found that the nickel concentration in the poor solution can be stabilized at a level lower than before, thus completing the present invention.

That is, according to the first invention of the present invention, in the sulfurization step of blowing hydrogen sulfide gas into the sulfuric acid aqueous solution (A) containing nickel and forming a sulfide (B) containing nickel and a poor solution,
As a seed crystal, there is provided a reaction control method for a sulfiding step, characterized in that the sulfide (B) corresponding to a nickel amount 4 to 6 times the amount of nickel contained in the sulfuric acid aqueous solution (A) is recycled. The

  Moreover, according to the second invention of the present invention, there is provided the reaction control method for the sulfiding step, characterized in that, in the first invention, the reaction temperature of the sulfiding step is 70 to 95 ° C.

  According to a third invention of the present invention, in the first or second invention, the aqueous sulfuric acid solution (A) is leached in a hydrometallurgical method based on high-temperature pressure leaching for recovering nickel from nickel oxide ore. There is provided a reaction control method for a sulfiding step, which is a mother liquor comprising a sulfuric acid aqueous solution containing nickel and cobalt recovered through a step, a solid-liquid separation step, and a neutralization step.

  According to a fourth invention of the present invention, in the third invention, the mother liquor has a nickel concentration of 2 to 5 g / L, a cobalt concentration of 0.1 to 1.0 g / L, and a pH Is 3.2 to 4.0, a method for controlling the reaction of the sulfiding step is provided.

  The reaction control method of the sulfiding step of the present invention is a reaction control method capable of sufficiently suppressing the adhesion of the product sulfide to the inner surface of the reaction vessel and stabilizing the nickel concentration in the poor liquid at a level lower than before. As such, its industrial value is extremely large. In particular, in a hydrometallurgical process based on high-temperature pressure leaching to recover nickel from nickel oxide ore, hydrogen sulfide gas is blown into a sulfuric acid aqueous solution containing nickel and cobalt to form sulfide and poor liquid containing nickel and cobalt. It is useful as a reaction control method for the sulfuration process.

  The reaction control method of the sulfidation step of the present invention is carried out by blowing hydrogen sulfide gas into a sulfuric acid aqueous solution (A) containing nickel, and forming a poor solution with the sulfide (B) containing nickel as a seed crystal. The sulfide (B) corresponding to a nickel amount 4 to 6 times the amount of nickel contained in the aqueous sulfuric acid solution (A) is recycled.

In the present invention, it is important to circulate and use the sulfide (B) corresponding to 4 to 6 times, preferably 4 to 5 times the amount of nickel contained in the sulfuric acid aqueous solution (A) as a seed crystal. . As a result, adhesion of the product sulfide to the inner surface of the reaction vessel can be sufficiently suppressed, and the nickel concentration in the poor liquid can be stabilized at a lower level than before.
In other words, since the sulfide circulated in the sulfidation process becomes the nucleus of the generation of newly generated sulfide, a sufficient generation rate of sulfide can be maintained even at a relatively low temperature where the reaction rate is low. it can. In addition, the presence of sulfide-generating nuclei makes the sulfide particles produced relatively large, so that the residence time in the reaction vessel is shortened and the particles are not deposited in the reaction vessel. Here, if the circulation usage is less than 4 times, the nickel concentration in the poor liquid increases and the nickel recovery rate decreases. On the other hand, if the circulation usage exceeds 6 times, no further effect can be expected.

The equipment used in the sulfidation process is not particularly limited, but a system in which a predetermined amount of sulfide is circulated in the sulfidation process is used.
FIG. 1 is a schematic diagram illustrating an example of equipment layout in the sulfurization process. In FIG. 1, in a stirred reaction tank 1, a seed crystal 6 made of a circulating sulfide slurry is added to a starting solution 4 made of a sulfuric acid aqueous solution containing nickel and cobalt, and further a hydrogen sulfide gas 5 is blown into the sulfide reaction. Done. The slurry after the reaction is sent to a sedimentation tank 2 such as a thickener, and the sulfide containing nickel is separated from the bottom as a concentrate slurry 7 and distributed through the relay tank 3 at a predetermined ratio. It is circulated to. On the other hand, the recovered sulfide 8 is extracted from the relay tank 3 and processed in the next step. Here, the flow rate of the starting liquid to the sulfiding process is measured and adjusted, and if it fluctuates, the flow rate of the sulfide slurry obtained from the thickener is adjusted to control the nickel concentration of the poor liquid. To do.

  The reaction temperature in the sulfiding step is not particularly limited, and is preferably 70 to 95 ° C, and more preferably a relatively low temperature of about 80 ° C. That is, the sulfurization reaction itself is generally promoted at higher temperatures. However, when the temperature exceeds 95 ° C., the temperature rises, and the reaction rate is high. There are many problems.

  The sulfuric acid aqueous solution (A) is not particularly limited and is widely applied to a sulfuric acid aqueous solution containing nickel and / or cobalt. Among them, high-temperature pressure leaching for recovering nickel from nickel oxide ore is used. In the hydrometallurgy method based on this, a mother liquor composed of a sulfuric acid aqueous solution containing nickel and cobalt recovered through a leaching step, a solid-liquid separation step, and a neutralization step is preferably used.

Below, the case where the reaction control method of the sulfidation process of the present invention is used in the high-temperature pressure acid leaching method of nickel oxide ore will be described.
FIG. 2 is a smelting process diagram showing an example of an embodiment of a high-temperature pressure acid leaching method of nickel oxide ore using the method of the present invention.
In FIG. 2, the nickel oxide ore 15 is first subjected to high-temperature pressure leaching using sulfuric acid in the leaching step 11 to form a leaching slurry 16. The leaching slurry 16 is subjected to the solid-liquid separation step 12 and, after being subjected to multi-stage washing, is separated into a leaching solution 17 containing nickel and cobalt and a leaching residue 18. The leachate 17 is subjected to a neutralization step 13 to form a neutralized starch slurry 19 containing trivalent iron hydroxide and a mother liquor 20 for nickel recovery. The mother liquor 20 is subjected to the sulfidation step 14 and separated into a poor liquid 22 from which nickel or the like has been removed and a sulfide 21 containing nickel and cobalt, but the produced sulfide 21 is recycled.

Next, an outline of each step of the high-temperature pressure acid leaching method will be described.
(1) Leaching step The leaching step is a step of adding sulfuric acid to a slurry of nickel oxide ore and stirring at a temperature of 220 to 280 ° C. to form a leaching slurry comprising a leaching residue and a leaching solution. In this step, a high-temperature pressurized container (autoclave) is used.

  Nickel oxide ores used in the leaching step are mainly so-called laterite ores such as limonite or saprolite ores. The nickel content of the laterite ore is usually 0.8 to 2.5% by weight, and is contained as a hydroxide or a siliceous clay (magnesium silicate) mineral. Further, the iron content is 10 to 50% by weight and is mainly in the form of trivalent hydroxide (goethite), but partly divalent iron is contained in the siliceous clay.

  In the leaching step, leaching as sulfates such as nickel and cobalt and leaching iron sulfate as hematite by leaching reaction and high-temperature thermal hydrolysis reaction represented by the following formulas (1) to (5) Immobilization is performed. However, since the fixation of iron ions does not proceed completely, the leaching slurry obtained usually contains divalent and trivalent iron ions in addition to nickel and cobalt.

"Leaching reaction"
MO + H ₂ SO ₄ ⇒ MSO ₄ + H ₂ O (1)
(In the formula, M 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 (2)
FeO + H ₂ SO ₄ ⇒ FeSO ₄ + H ₂ O (3)

"High temperature thermal hydrolysis reaction"
2FeSO ₄ + H ₂ SO ₄ + 1 / 2O ₂ ⇒ Fe ₂ (SO ₄ ) ₃ + H ₂ O (4)
_{Fe 2 (SO 4) 3 +} 3H 2 O⇒ Fe 2 O 3 + 3H 2 SO 4 (5)

The slurry concentration in the leaching step is not particularly limited, but it is preferably prepared so that the slurry concentration of the leaching slurry is 15 to 45% by weight.
The amount of sulfuric acid used in the leaching step is not particularly limited, and an excessive amount that leaches iron in the ore is used. For example, it is 300 to 400 kg per ton of ore, and per 1 ton of ore. If the amount of sulfuric acid added exceeds 400 kg, the sulfuric acid cost increases, which is not preferable.

(2) Solid-liquid separation process The said solid-liquid separation process is a process of obtaining the leaching liquid and leaching residue containing nickel and cobalt by carrying out multistage washing | cleaning of the leaching slurry formed at the said leaching process.

  The multi-stage cleaning in the solid-liquid separation step is not particularly limited, but a CCD method in which a counter current is brought into contact with a cleaning solution not containing nickel is preferable. 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 95% or more.

(3) Neutralization step The neutralization step is for recovering nickel and neutralized starch slurry containing trivalent iron by adding calcium carbonate so that the pH is 4 or less while suppressing oxidation of the leachate. This is a step of forming a mother liquor. In this way, the excess acid used in the high-temperature and high-pressure acid leaching step is neutralized, and trivalent iron ions remaining in the solution are removed.

The pH of the neutralization step is 4 or less, and 3.2 to 3.8 is particularly preferable. That is, when the pH exceeds 4, the generation of nickel hydroxide increases.
In the neutralization step, it is important not to oxidize iron ions present as divalent ions in the solution when removing trivalent iron ions remaining in the solution. Therefore, it is important to prevent oxidation of the solution as much as possible as well as air blowing. Thereby, the increase in the amount of calcium carbonate consumption and the amount of neutralized starch produced due to the removal of divalent iron can be suppressed. That is, an increase in nickel loss to the starch due to an increase in the amount of neutralized starch can be suppressed.

  As for the temperature of the said neutralization process, 50-80 degreeC is preferable. That is, if it is less than 50 degreeC, a starch will become fine and it will have a bad influence on a solid-liquid separation process. On the other hand, when it exceeds 80 ° C., the corrosion resistance of the device material is lowered and the energy cost for heating is increased.

(4) Sulfurization step The sulfidation step is a step in which hydrogen sulfide gas is blown into the mother liquor to form sulfide and poor solution containing nickel and cobalt. Here, as a seed crystal, a sulfide corresponding to a nickel amount 4 to 6 times the amount of nickel contained in the mother liquor is circulated and used.

  When zinc is contained in the mother liquor, a step of selectively separating zinc as a sulfide can be used prior to the step of separating nickel and cobalt as a sulfide. That is, by creating weak conditions during the sulfurization reaction, the speed of the sulfurization reaction is suppressed, and the coprecipitation of nickel having a higher concentration than zinc is suppressed, thereby selectively removing zinc.

  Examples of the mother liquor include a pH of 3.2 to 4.0, a nickel concentration of 2 to 5 g / L, a cobalt concentration of 0.1 to 1.0 g / L, and iron, magnesium, manganese as impurity components. Etc. These impurity components vary greatly depending on the redox potential of leaching, the operating conditions of the autoclave and the ore quality, but generally contain about several g / L of iron, magnesium and manganese. Here, a relatively large amount of impurity components exist with respect to nickel and cobalt to be recovered, but alkaline earth metals such as iron, manganese, alkali metals, and magnesium, which are low in stability as sulfides, are generated sulfides. Is not contained.

  By the sulfidation step, a sulfide containing nickel and cobalt with a small amount of impurities and a poor solution in which the nickel concentration is stabilized at a low level can be obtained. The poor solution includes an impurity element such as iron, magnesium, manganese, and the like that is contained without being sulfided at a pH of about 1 to 3. Moreover, nickel and cobalt which become recovery loss are few, for example, content of nickel and cobalt is 40 mg / L or less and 5 mg / L or less, respectively. Since this poor liquid contains almost no nickel and has a low pH, even if it is used as a cleaning liquid in the solid-liquid separation process, it does not cause the formation of hydroxide.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples. In addition, the analysis method of the metal used by the Example and the comparative example was performed by the ICP emission analysis method.
In addition, the nickel sulfate aqueous solution used in Examples and Comparative Examples is recovered through a leaching step, a solid-liquid separation step, and a neutralization step in a hydrometallurgical method based on high-temperature pressure leaching that recovers nickel from nickel oxide ore. The mother liquor was made of a sulfuric acid aqueous solution containing nickel, the nickel concentration was 4 g / L, and the pH was 3.5.

(Example 1)
Using the sulfiding equipment shown in FIG. Using the above nickel sulfate aqueous solution as a starting liquid, charging into a stirred reaction tank, and controlling the reaction temperature to 70 to 80 ° C., adding nickel sulfide produced by a sulfurization reaction as a seed crystal to the starting liquid Further, the sulfurization reaction was performed while blowing hydrogen sulfide gas. The slurry after the reaction was sent to a sedimentation tank, and nickel sulfide was separated from the bottom as a concentrate (Ni, Co sulfide slurry) 7 and circulated through a relay tank to a stirring reaction tank at a predetermined ratio. Here, the amount of nickel sulfide circulated was adjusted to 4.0 to 5.0 times the amount of nickel contained in the starting solution. After the reaction was stabilized, the nickel concentration of the poor solution was analyzed to determine the nickel recovery rate. Here, the starting liquid flow rate to the sulfiding step was changed in the range of 200 to 450 m ³ / h, and in conjunction with this, the circulation flow rate of the sulfide slurry obtained from the settling tank to the stirring reaction tank was adjusted. The results are shown in FIG.

(Comparative Example 1)
The same procedure as in Example 1 was conducted except that the amount of nickel sulfide circulated was adjusted to a nickel amount less than 2.0 times the amount of nickel contained in the starting solution. The concentration was analyzed and the nickel recovery rate was determined. The results are shown in FIG.

(Comparative Example 2)
Nickel sulfide circulation was carried out in the same manner as in Example 1 except that the nickel amount was more than 6.0 times the amount of nickel contained in the starting solution. The concentration was analyzed and the nickel recovery rate was determined. The results are shown in FIG.

As shown in FIG. 3, in Example 1, the circulating amount of nickel sulfide was adjusted to 4.0 to 5.0 times the amount of nickel contained in the starting liquid, and this was performed according to the present invention. It can be seen that a high nickel recovery rate is maintained and controlled regardless of changes in the starting liquid throughput.
On the other hand, in Comparative Examples 1 and 2, since the circulation amount of nickel sulfide does not meet these conditions, it can be seen that satisfactory results cannot be obtained in the nickel recovery rate.

  As is clear from the above, the reaction control method of the sulfiding step of the present invention sufficiently suppresses the formation of sulfides on the inner surface of the reaction vessel and stabilizes the nickel concentration in the poor liquid at a lower level than before. It is a reaction control method that can be performed, and is an effective method when hydrogen sulfide gas is blown into a sulfuric acid aqueous solution containing nickel to recover sulfide containing nickel, and nickel is further recovered from nickel oxide ore. In a hydrometallurgical method based on high-temperature pressure leaching, the method is particularly useful as a reaction control method in a sulfiding step for recovering a sulfide containing nickel and cobalt from an aqueous sulfuric acid solution containing nickel and cobalt.

It is the schematic showing an example of equipment arrangement | positioning of a sulfidation process. It is a smelting process figure showing an example of the embodiment of the high temperature pressurization acid leaching method of the nickel oxide ore using the method of the present invention. It is a figure showing the relationship between the starting liquid flow rate and nickel recovery rate by the circulation amount of nickel sulfide. (Example 1, Comparative Examples 1 and 2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stirring reaction tank 2 Sedimentation tank 3 Relay tank 4 Start liquid 5 Hydrogen sulfide gas 6 Seed crystal 7 Concentrate slurry 8 Recovered sulfide 11 Leaching process 12 Solid-liquid separation process 13 Neutralization process 14 Sulfurization process 15 Nickel oxide ore 16 Leaching slurry 17 Leachate 18 Leaching residue 19 Neutralized starch slurry 20 Mother liquor 21 Sulfide 22 Poor liquid

Claims (4)

In a sulfurization step of blowing hydrogen sulfide gas into a sulfuric acid aqueous solution (A) containing nickel to form a poor solution with a sulfide (B) containing nickel,
A reaction control method for a sulfiding step, characterized in that the sulfide (B) corresponding to a nickel amount 4 to 6 times the amount of nickel contained in the aqueous sulfuric acid solution (A) is circulated as a seed crystal.   The reaction control method of the sulfurization process according to claim 1, wherein the reaction temperature of the sulfurization process is 70 to 95 ° C.   The sulfuric acid aqueous solution (A) includes nickel and cobalt recovered through a leaching step, a solid-liquid separation step, and a neutralization step in a hydrometallurgical method based on high-temperature pressure leaching for recovering nickel from nickel oxide ore. 3. The reaction control method for a sulfurization process according to claim 1, wherein the reaction liquid is a mother liquor composed of an aqueous sulfuric acid solution.   The mother liquor has a nickel concentration of 2 to 5 g / L, a cobalt concentration of 0.1 to 1.0 g / L, and a pH of 3.2 to 4.0. The reaction control method of the sulfurization process as described.

Images