JP7293873B2 - Method for producing nickel sulfide, hydrometallurgical method for nickel oxide ore - Google Patents

Description

The present invention provides a method for producing nickel sulfide by adding a sodium hydrosulfide solution together with hydrogen sulfide gas to a sulfuric acid acidic solution containing nickel to cause a sulfurization reaction, and a nickel oxide ore obtained by applying the method to the sulfurization process. relates to a hydrometallurgical method of.

In hydrometallurgy using nickel oxide ore as a raw material, a technique called high pressure acid leaching (HPAL), which acid leaches valuable metals such as nickel and cobalt under high temperature and high pressure, has been put into practical use. there is In this HPAL method, a sulfiding agent such as hydrogen sulfide gas is added under pressure to a leachate containing valuable metals such as nickel and cobalt leached from nickel oxide ore to cause a sulfurization reaction to remove these valuable metals. This is a method of recovering as sulfide. Such a method has the advantage of being able to efficiently recover valuable metals even from low nickel grade nickel oxide ores.

More specifically, in the nickel oxide ore hydrometallurgical process based on the HPAL method, first, several kinds of low-grade nickel oxide ores are mixed so as to have a predetermined nickel grade and impurity grade, and then mixed with water. The slurried material is sieved, and only prescribed undersized ores are blended (ore blending step).

Next, the slurry of ore is fed into an autoclave and the nickel is sulfuric acid leached under high temperature and pressure (leaching step).

Next, the leached slurry obtained by leaching is neutralized (preliminary neutralization), and residual free acids are neutralized using limestone (preliminary neutralization step). After that, the leaching slurry is solid-liquid separated into a leaching solution and a leaching residue using a solid-liquid separator such as a thickener (solid-liquid separation step).

The separated leaching residue is sent to a tailing dam after removing heavy metals to a predetermined concentration in the final neutralization step. On the other hand, the leachate obtained by the solid-liquid separation undergoes a neutralization step for removing impurities, and then is sent to a sulfurization step where a sulfurization treatment using a sulfurizing agent such as hydrogen sulfide gas is performed. In addition, when zinc is contained in the post-neutralization liquid obtained through the neutralization process, the post-neutralization liquid is subjected to a sulfidation treatment under predetermined conditions to remove zinc as a sulfide. Liquid treatment is performed (liquid purification process (dezincification process)). Part of the post-sulfidation solution (poor solution) from which nickel has been separated through the sulfurization process is reused in the solid-liquid separation process after treatment in the preliminary neutralization process, and the surplus is used in the final neutralization process. The liquid is sent to the process for treatment (final neutralization process).

Here, the sulfurization step in the hydrometallurgical process described above will be described more specifically. In the sulfurization process, the post-neutralization liquid obtained through the neutralization treatment (or the post-purification liquid after the purification process) is sent to reaction tanks (sulfurization reaction tanks) configured in multiple stages, and each reaction tank A sulfide containing nickel (nickel sulfide) is precipitated by a continuous sulfurization reaction due to gas-liquid contact of the hydrogen sulfide gas blown into the gas phase. By aerating the slurry containing precipitated nickel sulfide before the solid-liquid separation treatment, the hydrogen sulfide gas dissolved in the solution is recovered and reused in the sulfurization reaction as recycled gas. Also, part of the nickel sulfide is repeated in the reactor as seed crystals (see, for example, Patent Document 1).

The sulfurization reaction tank is a closed container, and the pressure inside the reaction tank is adjusted by an exhaust line installed in the latter reaction tank among the multistage reaction tanks. The gas containing hydrogen sulfide discharged from the reaction tank is sent to a detoxification facility where the hydrogen sulfide is detoxified with an aqueous caustic soda solution and then released into the atmosphere. Part of the sodium hydrogen sulfide (sodium hydrosulfide) solution produced by the reaction of the aqueous solution of caustic soda and hydrogen sulfide in the gas is returned to the sulfurization reaction tank and used as an auxiliary agent for the sulfurization reaction, and the rest is It is sent to the final neutralization step (see Patent Document 2, for example).

By adding a sodium hydrosulfide solution as an auxiliary agent for the sulfurization reaction, the yield of nickel contained in the post-neutralization liquid (or the post-purification liquid) can be improved. On the other hand, if the sodium hydrosulfide solution is added excessively, the particle size of the precipitated nickel sulfide becomes finer, which causes poor dehydration in the solid-liquid separation process and increases the impurity grade in the nickel sulfide. Also, it induces deterioration of the handleability of nickel sulfide. Furthermore, since the amount of nickel sulfide leaking into the post-sulfidation liquid obtained after solid-liquid separation increases, the yield of nickel decreases.

Concerning such a problem, it is conceivable to send the surplus sodium hydrosulfide solution to the final neutralization step, but this is equivalent to discarding the caustic soda used in the detoxification equipment. Therefore, from the viewpoint of nickel yield and basic unit, it is desirable to repeat the entire amount of the sodium hydrosulfide solution produced in the system.

For this reason, in the hydrometallurgical process of nickel oxide ore described above, in order to improve the nickel yield and reduce the basic unit, while recovering the entire amount of the sodium hydrosulfide solution generated in the detoxification equipment, the sulfidation reaction A method capable of appropriately controlling the particle size of nickel sulfide to be produced is desired.

For example, Patent Document 3 discloses a mixed solution of a colloidal aqueous solution in which composite colloidal particles of a salt of a metal nobler than nickel and a protective colloidal agent are dispersed, a complexing agent, an alkaline substance, and a reducing agent. Disclosed is a method for producing sulfur-containing nickel powder, characterized by adding one or more sulfides of sodium hydrosulfide, ammonium hydrogen sulfide, sodium sulfide or ammonium sulfide after adding an aqueous nickel salt solution to there is However, there is no mention of particle size control of the sulfur-containing nickel powder.

JP 2016-160526 A JP 2010-126778 A JP 2015-160978 A

The present invention has been proposed in view of the circumstances described above. It is an object of the present invention to provide a method for appropriately controlling the particle size of nickel sulfide produced while reusing the entire sodium hydrosulfide solution.

The inventor of the present invention has made intensive studies to solve the above-described problems. As a result, using two or more reactors connected in series, the total amount of sodium hydrosulfide solution produced by detoxifying hydrogen sulfide gas is transferred to the first reactor on the most upstream side and its first reactor. The total amount of the sodium hydrosulfide solution is added by distributing it to the reaction tank in the latter stage of the first reaction tank and by setting the distribution ratio of the sodium hydrosulfide solution to the first reaction tank in a specific range. The inventors have found that the particle size of the nickel sulfide produced can be appropriately controlled while reusing the nickel sulfide, and have completed the present invention.

(1) A first aspect of the present invention is a nickel sulfide production method in which a nickel-containing sulfuric acid acid solution is placed in a reaction tank, and hydrogen sulfide gas is added to cause a sulfurization reaction to produce nickel sulfide. wherein unreacted gas out of the hydrogen sulfide gas added to the sulfuric acid acid solution is recovered, an aqueous sodium hydroxide solution is added to the recovered hydrogen sulfide gas to generate a sodium hydrosulfide solution, and water obtained adding the total amount of the sodium sulfide solution together with the hydrogen sulfide gas to the sulfuric acid acid solution to cause a sulfurization reaction, wherein the reaction tank is composed of two or more reaction tanks connected in series; The sodium hydrosulfide solution is distributed and added to the most upstream first reaction tank and the latter reaction tank of the first reaction tank, and out of the total amount of the sodium hydrosulfide solution, the most upstream In the method for producing nickel sulfide, the distribution ratio of the sodium hydrosulfide solution to the first reaction tank is in the range of 40 to 70%.

(2) A second aspect of the present invention is based on the first aspect, wherein the sodium hydrosulfide solution other than the sodium hydrosulfide solution to be distributed to the first reaction vessel on the most upstream side of the total amount of the sodium hydrosulfide solution is This is a method for producing nickel sulfide, in which nickel sulfide is added by being distributed to a second reaction tank that is continuous with one reaction tank.

(3) A third aspect of the present invention is a method for producing nickel sulfide according to the first or second aspect, wherein the nickel sulfide produced has a 50% particle size of 50 to 80 μm.

(4) In a fourth aspect of the present invention, in any one of the first to third aspects, while adjusting the addition ratio of the sodium hydrosulfide solution to the amount of nickel contained in the sulfuric acid acid solution within a predetermined range , a method for producing nickel sulfide, wherein the sodium hydrosulfide solution is added.

(5) A fifth aspect of the present invention is the fourth aspect, wherein the addition ratio of the sodium hydrosulfide solution to the amount of nickel contained in the sulfuric acid acidic solution is 0.72 to 1.09 m ³ /t-Ni. It is a method for producing nickel sulfide, in which the sodium hydrosulfide solution is added so as to obtain.

(6) A sixth aspect of the present invention is a hydrometallurgical method for nickel oxide ore in which nickel is leached from nickel oxide ore using sulfuric acid and nickel sulfide is produced from the obtained leachate, wherein the leachate is stored in a reaction tank, and hydrogen sulfide gas is added to cause a sulfurization reaction to generate nickel sulfide, wherein the sulfurization step includes unreacted hydrogen sulfide gas added to the leachate gas is recovered, an aqueous sodium hydroxide solution is added to the recovered hydrogen sulfide gas to generate a sodium hydrosulfide solution, and the entire amount of the resulting sodium hydrosulfide solution is added to the leachate together with the hydrogen sulfide gas to cause a sulfidation reaction The reaction tank is composed of two or more reaction tanks connected in series, the first reaction tank on the most upstream side, and the reaction in the latter stage of the first reaction tank The sodium hydrosulfide solution is distributed and added to the tank, and the distribution ratio of the sodium hydrosulfide solution to the first reaction tank on the most upstream side of the total amount of the sodium hydrosulfide solution is 40 to 70%. It is a hydrometallurgical method for nickel oxide ore in the range of

According to the present invention, when nickel sulfide is produced by sulfidation treatment, the particle size of nickel sulfide produced is reduced while reusing the entire sodium hydrosulfide solution produced by detoxifying hydrogen sulfide gas. can be properly controlled.

It is a process drawing which shows an example of the flow of sulfuration treatment. FIG. 2 is a schematic diagram for explaining the configuration of two or more multistage reaction vessels connected in series and the flow of supplying a sodium hydrosulfide solution produced by detoxifying unreacted hydrogen sulfide gas. BRIEF DESCRIPTION OF THE DRAWINGS It is process drawing which showed an example of the flow of the hydrometallurgy method of a nickel oxide ore. A graph showing the relationship between the D50 particle size of nickel sulfide and the sodium hydrosulfide solution addition ratio when the sodium hydrosulfide solution was added to the first reactor at each distribution ratio, based on the results of the examples. It is a diagram.

Specific embodiments of the present invention will be described in detail below. In addition, the present invention is not limited to the following embodiments, and various modifications are possible without changing the gist of the present invention. In this specification, the notation "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

≪1. Method for producing nickel sulfide»
The method for producing nickel sulfide according to the present invention is a method for obtaining nickel sulfide by adding hydrogen sulfide gas to a sulfuric acid acid solution containing nickel contained in a reaction tank to cause a sulfurization reaction. For example, this production method can be applied to the sulfurization step in the nickel oxide ore hydrometallurgical process, which will be described later in detail.

In the hydrometallurgical process, cobalt is also contained in the sulfuric acid acidic solution to be treated (raw material), and a so-called mixed sulfide containing nickel and cobalt is obtained by a sulfurization reaction. Therefore, "nickel sulfide" is a sulfide containing at least nickel, and also includes mixed sulfides of nickel and cobalt.

Specifically, in the method for producing nickel sulfide according to the present invention, unreacted gas out of hydrogen sulfide gas added to a sulfuric acid acidic solution containing nickel is recovered, and an aqueous sodium hydroxide solution is added to the recovered hydrogen sulfide gas. adding to form a sodium hydrosulfide solution and adding the total amount of the resulting sodium hydrosulfide solution along with hydrogen sulfide gas to the sulfuric acid acid solution to effect the sulfidation reaction.

In this production method, the reaction tank (sulfurization reaction tank) in which the sulfuric acid acid solution is accommodated and where the sulfurization reaction occurs is composed of two or more reaction tanks connected in series. A sodium hydrosulfide solution is distributed and added to one reactor and to the reactors subsequent to the first reactor. Then, the distribution ratio of the sodium hydrosulfide solution to the first reaction vessel on the most upstream side of the total amount of the sodium hydrosulfide solution is in the range of 40 to 70%.

Here, for example, in the nickel oxide ore hydrometallurgical process as described above, nickel is leached from the nickel oxide ore using sulfuric acid under high temperature and high pressure, and sulfidation is performed to generate nickel sulfide from the resulting leachate. have a process. In the sulfurization treatment in the sulfurization step, for example, hydrogen sulfide gas with a purity of about 95% to 99% is used as a sulfurizing agent, and an amount (excess) of hydrogen sulfide gas that is larger than the theoretical equivalent required to generate sulfide by a sulfurization reaction. is added to a sulfuric acid acid solution containing nickel, which is the starting solution for the sulfurization reaction. As a result, nickel contained in the sulfuric acid acid solution can be recovered as sulfide at a high recovery rate.

On the other hand, in the sulfurization treatment in the sulfurization process, since an excessive amount of hydrogen sulfide gas is added, unreacted gas that did not participate in the sulfurization reaction remains in the reaction vessel. Therefore, in the sulfurization treatment, unreacted gas among the added hydrogen sulfide gas is recovered, sodium hydroxide is added to the recovered hydrogen sulfide gas to generate a sodium hydrosulfide solution, and the resulting sodium hydrosulfide solution is added to the sulfuric acid acid solution together with hydrogen sulfide gas as a sulfiding agent. As a result, nickel in the sulfuric acid acid solution can be recovered as sulfide at a higher recovery rate, and the utilization efficiency of hydrogen sulfide gas can be improved. Furthermore, it is possible to prevent the generated nickel sulfide from becoming finer and to appropriately control the particle size.

Specifically, unreacted hydrogen sulfide gas is recovered to produce a sodium hydrosulfide solution, and the entire amount is repeated for the sulfurization treatment. Therefore, in the sulfurization treatment, in addition to the sulfurization reaction with hydrogen sulfide gas as shown in the following formula [1], a sulfurization reaction with sodium hydrosulfide as shown in the following formula [2] occurs. Note that M in the formula represents Ni or Co.
_MSO4 + _H2S →MS+ _H2SO4 ... _[ 1]
2NaHS _{+ MSO4} → _Na2SO4 +MS+ _H2S [2]

FIG. 1 is a process chart showing an example of the flow of sulfuration treatment. As shown in FIG. 1, in the sulfurization treatment, a nickel-containing sulfuric acid acid solution is charged into a reaction tank, an excess amount of hydrogen sulfide gas is added to the gas phase of the reaction tank, and the hydrogen sulfide gas is Nickel-containing sulfides are precipitated by continuous sulfurization reaction due to gas-liquid contact. At this time, from the viewpoint of the yield of nickel and the like, the amount of hydrogen sulfide gas blown into the reaction tank is determined by the amount of supplied sulfuric acid acid solution to be subjected to sulfurization treatment and the concentration of nickel sulfate contained in the solution, that is, the amount of nickel to be supplied. depends on

The nickel sulfide produced by the sulfurization reaction is separated in the form of a concentrated slurry from the poor solution (post-sulfurization solution) in which the nickel concentration has been stabilized at a low level. A portion of nickel sulfide in the form of a concentrated slurry is withdrawn as seed crystals and returned to the reactor. As a result, sulfide is precipitated by a sulfurization reaction with the seed crystal as a nucleus, so that the nickel sulfide particles to be produced can be stably grown without large variations in particle size.

On the other hand, the unreacted hydrogen sulfide gas remaining in the reaction tank is recovered and charged into the detoxification equipment. In the detoxification equipment, a detoxification treatment is performed using hydrogen sulfide gas, specifically, a detoxification treatment is performed using an aqueous sodium hydroxide solution to generate a sodium hydrogen sulfide (sodium hydrosulfide) solution. This sodium hydrosulfide solution is a solution containing sodium hydroxide and has a pH of about 13 or more.

The resulting sodium hydrosulfide solution is cycled into the reactor where the sulfiding treatment is carried out and added to an acidic solution containing nickel together with hydrogen sulfide gas as a sulfiding agent. This results in reactions [1] and [2] above.

However, simply adding hydrogen sulfide gas and a sodium hydrosulfide solution as a sulfiding agent to the acidic solution of sulfuric acid in the reaction vessel will cause nickel sulfide particles to have a 50% particle size (D50) exceeding 80 μm. can be coarse. Also, if the sodium hydrosulfide solution is added excessively, the particles of nickel sulfide to be produced become too fine, causing poor dehydration in the solid-liquid separation treatment and possibly increasing the quality of impurities. On the other hand, from the viewpoint of the yield of nickel and the like and the basic unit, it is desirable to repeatedly use the entire amount of the sodium hydrosulfide solution produced by the detoxification treatment in the system.

Therefore, in the method for producing nickel sulfide according to the present invention, a multi-stage reaction tank, that is, two or more reaction tanks connected in series are used, and the first reaction tank on the most upstream side and the first reaction tank A sodium hydrosulfide solution is added in portions to the subsequent reactors. Here, the "later-stage reaction vessel" means a multi-stage reaction vessel composed of a first reaction vessel, a second reaction vessel, ... an n-th reaction vessel (where n is 2 or more) from upstream to downstream. In, the reaction tank after the second reaction tank.

Then, the distribution ratio of the sodium hydrosulfide solution to the first reaction vessel on the most upstream side of the total amount of the sodium hydrosulfide solution is in the range of 40 to 70%. Here, the distribution ratio refers to the amount of the sodium hydrosulfide solution distributed and added to a specific reaction tank among the reaction tanks provided in multiple stages with respect to the total amount of the sodium hydrosulfide solution.

In this way, the reaction tanks for causing the sulfurization reaction are configured in multiple stages, and the sodium hydrosulfide solution is distributed and added to the first reaction tank and the subsequent reaction tanks of the first reaction tank. By adjusting the distribution ratio to the reaction tank of No. 1 to a specific range, that is, by adjusting the distribution ratio to a range of 40 to 70%, the 50% particle size (D50) of the nickel sulfide particles to be produced is stabilized. can be controlled to Specifically, the particle size D50 can be stably controlled within the range of about 50 to 80 μm. In addition, since the entire amount of the sodium hydrosulfide solution generated by the detoxification process is distributed and added to the reaction tank, there is no need to dispose of the sodium hydrosulfide solution containing sodium hydroxide used for detoxification. The processing cost for is reduced, and efficient production of nickel sulfide can be realized.

With respect to the distribution ratio to the first reactor, if it is less than 40%, the yield of nickel decreases. In addition, the grain size of nickel sulfide tends to become finer as the distribution ratio is increased.

FIG. 2 is a schematic for explaining the configuration of two or more multistage reaction vessels connected in series and the flow of supplying a sodium hydrosulfide solution produced by detoxifying unreacted hydrogen sulfide gas. It is a diagram. Note that FIG. 2 shows an example in which the reaction tanks (first reaction tank 11 to fourth reaction tank 14) are configured in four consecutive stages.

As shown in FIG. 2, in the reaction tanks composed of four stages of the first reaction tank 11 to the fourth reaction tank 14, the first reaction tank 11 on the most upstream side contains a sulfuric acid acidic solution containing nickel ( For example, when the post-cleaning solution after dezincing treatment in the hydrometallurgical process of nickel oxide ore is charged, hydrogen sulfide gas, which is a sulfiding agent, is blown in to cause a sulfidation reaction. The slurry containing nickel sulfide produced by the sulfurization reaction is transferred to the second reaction tank 12 following the first reaction tank 11, and hydrogen sulfide gas is similarly blown into the second reaction tank 12. A sulfidation reaction occurs that produces nickel sulfide. Similarly, the slurry containing nickel sulfide is transferred to the third reaction tank 13 and the fourth reaction tank 14 in sequence, and the sulfurization reaction occurs in each reaction tank. As a result, the slurry containing nickel sulfide is gradually concentrated, and the nickel sulfide is recovered through solid-liquid separation.

Hydrogen sulfide gas, which is a sulfiding agent, may be added to all of the two or more multistage reaction tanks, or may be added only to the first reaction tank. For example, by adding hydrogen sulfide gas only to the first reaction tank, the sulfurization reaction time in the first reaction tank can be maximized, nickel sulfide can be produced more effectively, and nickel can be collected. rate can be improved.

On the other hand, although not particularly limited, unreacted hydrogen sulfide gas that has not been involved in the sulfurization reaction is recovered from the third reaction tank 13 and the fourth reaction tank 14 and transferred to the detoxification equipment 21 . In the detoxification equipment 21, a detoxification process is performed in which a sodium hydroxide solution is added to the recovered hydrogen sulfide gas to generate sodium hydrosulfide. The gas components rendered harmless by the detoxification treatment in the detoxification equipment 21 are released into the atmosphere, and the sodium hydrosulfide solution produced by the detoxification treatment is repeatedly added to the reaction tank where the sulfidation treatment is performed. As a result, in the reactor (for example, the first reactor 11), the sodium hydrosulfide solution is added together with the hydrogen sulfide gas, causing a sulfurization reaction (reaction formulas [1] and [2] above).

At this time, the entire amount of the sodium hydrosulfide solution produced is repeated in the reaction vessel, and the first reaction vessel 11 on the most upstream side and the reaction vessel in the rear stage of the first reaction vessel 11 (second reaction vessel) 12 to at least one of the 4th reaction tanks). Specifically, the schematic diagram of FIG. 2 shows an example in which the sodium hydrosulfide solution is distributed to the first reaction tank 11 and the second reaction tank 12 .

Then, when adding the total amount of the sodium hydrosulfide solution distributed to the first reaction tank 11 and the second reaction tank 12, the ratio of the distributed addition amount of the sodium hydrosulfide solution added to the first reaction tank 11 ( distribution ratio) is in the range of 40 to 70%.

Here, the number of reaction tanks provided in multiple stages (number of installations) is not limited to four as shown in the schematic diagram of FIG. 2, and may be two or three, or five or more. may be

In addition, in the reaction tanks provided in multiple stages, when the sodium hydrosulfide solution is distributed and added to the first reaction tank on the most upstream side and the reaction tank in the rear stage of the first reaction tank, the first reaction It is preferred to distribute and add to two reaction tanks, a second reaction tank which is continuous with the first reaction tank. For example, in the case of the example of the schematic diagram of FIG. Dispense the entire amount of sodium hydrosulfide solution into each. As shown in FIG. 2, in the first reaction tank 11, a predetermined amount of nickel sulfide is added as a seed crystal, and nickel sulfide is produced with the seed crystal as a nucleus. In the following second reactor 12, mainly grain growth occurs due to the sulfidation reaction, based on the nickel sulfide produced.

Thus, sodium hydrosulfide solution was added to two reactors, a first reactor and a second reactor, which are the upstream reactors in which the formation and initial growth of nickel sulfide particles primarily occur. By distributing and adding the whole amount of, it is possible to prevent the nickel sulfide particles to be formed from becoming finer and to more stably control the particle size of the nickel sulfide.

Moreover, when adding the sodium hydrosulfide solution, it is preferable to adjust the addition ratio of the sodium hydrosulfide solution to the amount of nickel contained in the sulfuric acid acid solution within a predetermined range. Thus, by adding the sodium hydrosulfide solution while adjusting the addition ratio of the sodium hydrosulfide solution to the amount of nickel within a predetermined range, the particle size of the nickel sulfide to be produced can be further stably adjusted to the desired value. Range can be controlled.

Specifically, it is preferable to add the sodium hydrosulfide solution so that the addition ratio of the sodium hydrosulfide solution to the amount of nickel contained in the sulfuric acid acid solution is 0.72 to 1.09 m ³ /t-Ni. ^If the addition ratio of the sodium hydrosulfide solution is less than 0.72 m ³ /t, the basic unit of sodium hydroxide used for the abatement treatment deteriorates. Particles tend to be fine, which may lead to an increase in impurity quality and deterioration of handling properties. If the distribution ratio is 40% or less, the yield of nickel decreases, and as the ratio increases, the grain size of nickel sulfide becomes finer, so it is preferable to adjust the distribution ratio to about 70%.

The 50% particle size (D50) of nickel sulfide particles to be produced is preferably in the range of about 50 to 80 μm. If the particle size of nickel sulfide exceeds 80 μm in D50, the nickel leaching rate will decrease in chlorine leaching treatment using nickel sulfide as a raw material or pressure leaching treatment in an autoclave. Problems can arise that cause wear and tear on the

On the other hand, when the particle size of nickel sulfide is less than 50 μm in terms of D50, the dehydration property when solid-liquid separation is performed from the slurry containing nickel sulfide using a solid-liquid separation device such as a pressure filter is lowered, which is desirable. It may be necessary to use a larger than standard solid-liquid separator to ensure a throughput of . In addition, it is necessary to increase the number of solid-liquid separators, and there is a possibility that the facility cost will be significantly increased. Also, fine nickel sulfide particles of less than 50 μm are easily oxidized, which may adversely affect the quality.

≪2. Hydrometallurgical method of nickel oxide ore>>
The method for hydrometallurgical refining of nickel oxide ore according to the present invention is a method of leaching nickel from nickel oxide ore using sulfuric acid at high temperature and high pressure, and producing nickel sulfide from the obtained leaching solution. This hydrometallurgical method includes a sulfurization step in which a leachate, which is a sulfuric acid acid solution containing nickel, is placed in a reaction tank, and hydrogen sulfide gas is added to cause a sulfurization reaction to generate nickel sulfide.

Then, in the sulfurization step in this hydrometallurgical method, the method for producing nickel sulfide described above can be applied.

Specifically, in the sulfurization step, unreacted gas out of the hydrogen sulfide gas added to the leachate, which is an acidic solution of sulfuric acid, is recovered, and an aqueous sodium hydroxide solution is added to the recovered hydrogen sulfide gas to obtain sodium hydrosulfide. Forming a solution and adding all of the resulting sodium hydrosulfide solution to the leachate along with hydrogen sulfide gas to effect a sulfidation reaction. The reaction tanks for causing the sulfurization reaction are composed of two or more reaction tanks connected in series. Add the sodium hydrosulfide solution in portions. Then, the distribution ratio of the sodium hydrosulfide solution to the first reaction vessel on the most upstream side of the total amount of the sodium hydrosulfide solution is in the range of 40 to 70%.

According to such a method, the reaction tanks for causing the sulfurization reaction are configured in multiple stages, and the sodium hydrosulfide solution is distributed and added to the first reaction tank and the subsequent reaction tanks of the first reaction tank. In addition, by adjusting the distribution ratio to the first reaction tank to a specific range, that is, by adjusting the distribution ratio to a range of 40 to 70%, nickel sulfide particles generated in the sulfurization process are reduced. The 50% particle size (D50) can be stably controlled. Specifically, the particle size D50 can be stably controlled within the range of about 50 to 80 μm.

In addition, since the entire amount of the sodium hydrosulfide solution generated by the detoxification process is distributed and added to the reaction tank, there is no need to dispose of the sodium hydrosulfide solution containing sodium hydroxide used for detoxification. The processing cost for is reduced, and efficient production of nickel sulfide can be realized.

In the following, an outline of the hydrometallurgical method for nickel oxide ore will be described, and a specific embodiment in which the above-described method for producing nickel sulfide is applied to the sulfidation step in the hydrometallurgical method will be described. . As a hydrometallurgical method for nickel oxide ore, a hydrometallurgical method by a high temperature pressure acid leaching method (HPAL method) in which leaching is performed at high temperature and high pressure will be described as an example.

<Regarding each step of the hydrometallurgical method for nickel oxide ore>
FIG. 3 is a process chart showing an example of the flow of a hydrometallurgical method for nickel oxide ore. As shown in FIG. 3, the nickel oxide ore hydrometallurgical method includes a leaching step S1 in which sulfuric acid is added to a nickel oxide ore slurry as a raw material and subjected to leaching treatment under high temperature and high pressure, and a residue is separated from the leached slurry. a solid-liquid separation step S2 in which a leachate containing nickel is obtained by adjusting the pH of the leachate to separate impurity elements in the leachate as neutralized sediment to obtain a post-neutralization solution; a neutralization step S3 in which a solution after neutralization is obtained; and a sulfurization step (nickel recovery step) S4 for generating nickel sulfide by adding hydrogen sulfide gas to the.

(1) Leaching step In the leaching step S1, sulfuric acid is added to nickel oxide ore slurry (ore slurry) using a high-temperature pressurized reaction tank such as an autoclave, and the temperature is about 230 ° C. to 270 ° C. and the pressure is about 3 to 5 MPa. to produce a leach slurry consisting of the leach solution and leach residue.

Nickel oxide ores mainly include so-called laterite ores such as limonite ores and saprolite ores. The nickel content of laterite ores is typically 0.8% to 2.5% by weight and is contained as a hydroxide or magnesium silicate (magnesium silicate) mineral. In addition, the content of iron is 10% to 50% by weight, and it is mainly in the form of trivalent hydroxide (goethite), but some divalent iron is contained in magnesium minerals. . In the leaching step S1, in addition to such laterite ore, oxide ore containing valuable metals such as nickel, cobalt, manganese, and copper, such as manganese nodules existing in the deep seabed, can be used.

In the leaching treatment, nickel, cobalt, etc. are leached as sulfates, and the leached iron sulfate is fixed as hematite. However, since iron ions do not completely immobilize, the liquid portion of the obtained leaching slurry usually contains divalent and trivalent iron ions in addition to nickel, cobalt, and the like. In the leaching step S1, the obtained leaching solution is adjusted to have a pH of 0.1 to 1.0 from the viewpoint of filterability of the leaching residue containing hematite produced in the subsequent solid-liquid separation step S2. preferably.

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

(2) Solid-Liquid Separation Step In the solid-liquid separation step S2, the leaching slurry produced in the leaching step S1 is washed in multiple stages to separate the leaching solution containing valuable metals such as nickel and cobalt from the leaching residue.

In the solid-liquid separation step S2, after the leaching slurry is mixed with the cleaning liquid, solid-liquid separation processing is performed using a solid-liquid separation device such as a thickener. Specifically, first, the leaching slurry is diluted with a cleaning liquid, and then the leaching residue in the leaching slurry is concentrated as a thickener sediment. As a result, nickel and cobalt adhering to the leaching residue can be reduced according to the degree of dilution. In actual operation, the recovery rate of nickel and cobalt can be improved by connecting thickeners having such functions in multiple stages.

(3) Neutralization step In the neutralization step S3, a neutralizing agent such as magnesium oxide or calcium carbonate is added so that the pH of the leachate becomes 4 or less while suppressing oxidation of the leachate. A neutralized sediment slurry containing iron and a post-neutralization solution as a mother liquor for recovering nickel are obtained.

In the neutralization treatment, the pH of the resulting neutralized liquid is 4 or less, preferably 3.0 to 3.5, more preferably 3.1 to 3.2, while suppressing oxidation of the separated leachate. , a neutralizing agent such as calcium carbonate is added to the leachate to form a post-neutralization solution serving as a mother liquor for recovering nickel and a slurry of neutralized precipitate containing trivalent iron as an impurity element. . In the neutralization step S3, by performing the neutralization treatment (liquid purification treatment) on the leaching solution in this way, the excess acid used in the leaching treatment by the HPAL method is neutralized to produce a post-neutralization solution and a solution. Impurities such as trivalent iron ions and aluminum ions remaining therein are removed as neutralization precipitates.

(4) Sulfurization step (nickel recovery step)
In the sulfurization step S4, the post-neutralization solution, which is a sulfuric acid acid solution containing nickel, is used as the starting solution for the sulfurization reaction, and a sulfurizing agent is added to the starting solution for the sulfurization reaction to cause the sulfurization reaction, thereby producing nickel containing few impurities. A sulfide and a poor solution (post-sulfidation solution) in which the nickel concentration is stabilized at a low level are produced. If zinc is contained in the neutralized solution, zinc can be selectively separated as sulfide before nickel is separated as sulfide. The process of performing dezincing treatment is also called a solution purification process, and the solution after dezincification treatment is also called a post-purification solution.

The sulfurization treatment can be performed using a sulfurization reaction tank. Specifically, hydrogen sulfide gas, which is a sulfiding agent, is blown into the gas phase portion of the reaction tank for the starting solution of the sulfurization reaction (sulfuric acid acid solution containing nickel) contained in the sulfurization reaction tank, and hydrogen sulfide is added to the solution. Dissolving the gas causes a sulfidation reaction. By this sulfurization treatment, the nickel contained in the starting liquid of the sulfurization reaction is fixed as a sulfide and recovered.

After completion of the sulfurization reaction, the obtained slurry containing nickel sulfide is put into a sedimentation separation apparatus such as a thickener and subjected to a sedimentation separation treatment, and only the sulfide is separated and recovered from the bottom of the thickener. Part of the recovered nickel sulfide is returned to the reaction tank for sulfurization as seed crystals (R in the figure). On the other hand, the aqueous solution component overflows from the upper part of the thickener and is collected as a poor liquid.

The sulfurization reaction tank used for the sulfurization treatment is not particularly limited, but a reaction tank consisting of two or more tanks, preferably three or more tanks, more preferably four or more tanks connected in series is used ( For example, see FIG. 2). In two or more multi-stage sulfurization reaction tanks, a sulfuric acid acidic solution containing nickel, which is the starting solution for the sulfurization reaction, is supplied to the most upstream reaction tank (first reaction tank), and the reaction tanks By blowing hydrogen sulfide gas from the gas blowing port at , the sulfuration reaction is caused successively and continuously.

In the multi-stage reaction tanks, mainly in the first reaction tank, a nickel sulfide production reaction based on a sulfurization reaction occurs, and in the following second reaction tank and thereafter, the so-called growth of the nickel sulfide produced occurs.

Here, in the above-described sulfurization step S4, the post-neutralization solution (or post-purification solution), which is a sulfuric acid acid solution containing nickel, is subjected to a sulfurization treatment to generate nickel sulfide, and the added hydrogen sulfide gas is removed. The unreacted gas is recovered, an aqueous sodium hydroxide solution is added to the recovered hydrogen sulfide gas to generate a sodium hydrosulfide solution, and the resulting sodium hydrosulfide solution is added to the sulfuric acid acid solution together with the hydrogen sulfide gas. including.

At this time, in the hydrometallurgy method according to the present invention, the total amount of the sodium hydrosulfide solution obtained together with the hydrogen sulfide gas is transferred to the first, most upstream, of the two or more reaction vessels connected in series. The sulfidation reaction is effected by the distributed addition of the sodium hydrosulfide solution to the reactor and the reactors subsequent to the first reactor. Then, the distribution ratio of the sodium hydrosulfide solution to the first reaction vessel on the most upstream side of the total amount of the sodium hydrosulfide solution is in the range of 40 to 70%.

In the sulfurization step S4, the 50% particle size (D50) of the nickel sulfide particles generated in the sulfurization step can be stably controlled by performing the sulfurization treatment by such a method. Specifically, the particle size D50 can be stably controlled within the range of about 50 to 80 μm. In addition, since the entire amount of the sodium hydrosulfide solution generated by the detoxification process is distributed and added to the reaction tank, there is no need to dispose of the sodium hydrosulfide solution containing sodium hydroxide used for detoxification, which improves efficiency. production of nickel sulfide can be realized.

Also, preferably, sodium hydrosulfide solution is added to two reactors, a first reactor and a second reactor, which are upstream reactors where the formation and initial growth of nickel sulfide particles primarily occur. Distribute and add the total amount of

Further, when adding the sodium hydrosulfide solution, the addition ratio of the sodium hydrosulfide solution to the amount of nickel contained in the acidic solution of sulfuric acid is within a predetermined range, more preferably the addition ratio of the sodium hydrosulfide solution is 0.72-1. 09 m ³ /t-Ni.

As a result, the particle size of nickel sulfide to be produced can be more stably controlled within a desired range.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[Example 1]
Nickel sulfide was produced by a nickel oxide ore hydrometallurgical process (HPAL process, see FIG. 3). In the sulfurization step, a post-purification solution (initial reaction solution), which is a sulfuric acid acid solution containing nickel, is added to the first reaction tank (see FIG. 2), which is the most upstream of the four reaction tanks connected in series. A reaction starting solution was supplied to the first reaction tank 11), and hydrogen sulfide gas having a purity of 99% by volume was blown into the first reaction tank as a sulfiding agent.

The post-purification liquid, which is a sulfuric acid acid solution containing nickel, has a nickel concentration of 3.7 g/L, and was supplied to the first reaction tank at a flow rate of 1200 m ³ /hr. Further, the supply flow rate of the hydrogen sulfide gas to the first reaction tank was set at 1560 Nm ³ /hr, and the hydrogen sulfide gas was blown into the liquid phase portion of the reaction tank. Further, in the first reaction tank, part of the concentrated slurry having a slurry concentration of 1130 g/L obtained by concentrating the slurry containing nickel sulfide extracted from the fourth reaction tank on the most downstream side with a thickener. Repeated as seed crystals. The amount of seed crystals to be added was adjusted so that the amount of nickel in the acidic aqueous solution of sulfuric acid supplied to the first reaction vessel per unit time was repeatedly 45% by mass per unit time.

In addition, the unreacted gas of the added hydrogen sulfide gas is recovered, and the sodium hydrosulfide solution produced by adding a sodium hydroxide solution to the recovered hydrogen sulfide gas and performing a detoxification treatment is used as the hydrogen sulfide gas. was added to the acidic solution of sulfuric acid as a sulfiding agent to cause a sulfiding reaction.

In the abatement treatment for unreacted hydrogen sulfide gas, the gases discharged from the gas phase portions of the third and fourth reaction tanks are introduced into the abatement equipment (see FIG. 2), and the inside thereof is was brought into gas-liquid contact with a circulating sodium hydroxide solution having a concentration of 25% by mass, and the unreacted gas was absorbed by the sodium hydroxide solution to produce a sodium hydrosulfide solution.

In Example 1, the total amount of the generated sodium hydrosulfide solution (2% concentration) was supplied at a flow rate of 3.6 m ³ /hr (corresponding to 0.30% of the supply flow rate of the sulfuric acid acidic solution as the reaction starting solution). , were distributed and added to the first and second reactors. Here, the distribution ratio of the sodium hydrosulfide solution to the first reaction tank was in the range of 50-60%. Further, the addition ratio of the sodium hydrosulfide solution to the amount of nickel contained in the sulfuric acid acidic solution, which is the initial reaction solution, was varied within the range of 0.78 to 1.06 m ³ /t-Ni.

Thus, the sulfurization treatment in the sulfurization process was carried out, and the average particle size (D50) of nickel sulfide produced was measured. The metal analysis is performed by ICP emission spectrometry, and the particle size of nickel sulfide is measured by particle size distribution measurement based on the laser diffraction scattering method using a Microtrac particle size analyzer (manufactured by Horiba, Ltd., LA-950V2). gone.

[Example 2]
In Example 2, the distribution ratio of the sodium hydrosulfide solution to the first reaction tank was in the range of 40 to 50%, and the addition of the sodium hydrosulfide solution relative to the amount of nickel contained in the sulfuric acid acidic solution that was the initial reaction solution. The ratio was varied in the range of 0.90-1.09 ^{m 3} /t-Ni. Otherwise, sulfuration treatment was carried out in the same manner as in Example 1 to produce nickel sulfide.

[Example 3]
In Example 3, the distribution ratio of the sodium hydrosulfide solution to the first reaction tank was in the range of 60 to 70%, and the addition of the sodium hydrosulfide solution to the amount of nickel contained in the sulfuric acid acidic solution that was the initial reaction solution. The ratio was varied in the range of 0.72-0.89 m ³ /t-Ni. Otherwise, sulfuration treatment was carried out in the same manner as in Example 1 to produce nickel sulfide.

Table 1 below shows the conditions of the distribution ratio and the addition ratio of the sodium hydrosulfide solution in Examples 1 to 3, and the measurement results of the D50 particle size of the produced nickel sulfide. Further, FIG. 4 is a graph showing the relationship of the D50 particle size to the addition ratio of the sodium hydrosulfide solution when the sodium hydrosulfide solution is added to the first reaction tank at each distribution ratio based on the measurement results. indicates

As shown in the results of Examples 1 to 3, by setting the distribution ratio of the sodium hydrosulfide solution to the first reaction tank within a specific range, regardless of the addition ratio of the sodium hydrosulfide solution, The grain size of nickel sulfide to be produced can be controlled within the range of 50 μm to 80 μm.

In addition, since the entire amount of the sodium hydrosulfide solution produced by the detoxification treatment can be added to the system, it is possible to improve the yield of nickel and reduce the unit consumption.

Here, as can be seen from the graph of FIG. 4, as the distribution ratio to the first reaction tank increases, the average particle size of nickel sulfide produced decreases. From this, it is presumed that, for example, when the total amount of the sodium hydrosulfide solution is added only to the first reaction tank, the particles of nickel sulfide become fine.

11 first reaction tank 12 second reaction tank 13 third reaction tank 14 fourth reaction tank 21 abatement equipment

Claims (2)

A nickel sulfide production method for obtaining nickel sulfide by placing a sulfuric acid acid solution containing nickel in a reaction tank and adding hydrogen sulfide gas to cause a sulfurization reaction,
Unreacted gas out of the hydrogen sulfide gas added to the sulfuric acid acidic solution is recovered, an aqueous sodium hydroxide solution is added to the recovered hydrogen sulfide gas to generate a sodium hydrosulfide solution, and the resulting sodium hydrosulfide solution is adding the whole amount to the sulfuric acid acidic solution together with the hydrogen sulfide gas to cause a sulfurization reaction;
The reaction tank is composed of two or more reaction tanks connected in series,
The sodium hydrosulfide solution is distributed and added to the most upstream first reaction tank and the latter reaction tank of the first reaction tank, and out of the total amount of the sodium hydrosulfide solution, the most upstream Adjusting the distribution ratio of the sodium hydrosulfide solution to the first reaction tank in the range of 40 to 70%,
The addition ratio of the sodium hydrosulfide solution to the first reaction tank with respect to the amount of nickel contained in the sulfuric acid acidic solution, which is the reaction starting solution, is adjusted to be 0.72 to 1.09 m ³ /t-Ni. hand,
so that the 50% particle size of the generated nickel sulfide is 50 to 80 μm,
A method for producing nickel sulfide. In a hydrometallurgical method for nickel oxide ore in which nickel is leached using sulfuric acid for nickel oxide ore and nickel sulfide is produced from the resulting leachate,
including a sulfurization step of placing the nickel-containing sulfuric acid acid solution obtained from the leachate in a reaction tank and adding hydrogen sulfide gas to cause a sulfurization reaction to generate nickel sulfide;
The sulfurating step includes
Unreacted gas out of the hydrogen sulfide gas added to the sulfuric acid acidic solution is recovered, an aqueous sodium hydroxide solution is added to the recovered hydrogen sulfide gas to generate a sodium hydrosulfide solution, and the resulting sodium hydrosulfide solution is adding the whole amount to the sulfuric acid acidic solution together with the hydrogen sulfide gas to cause a sulfurization reaction;
The reaction tank is composed of two or more reaction tanks connected in series,
The sodium hydrosulfide solution is distributed and added to the most upstream first reaction tank and the latter reaction tank of the first reaction tank, and out of the total amount of the sodium hydrosulfide solution, the most upstream Adjusting the distribution ratio of the sodium hydrosulfide solution to the first reaction tank in the range of 40 to 70%,
The addition ratio of the sodium hydrosulfide solution to the first reaction tank with respect to the amount of nickel contained in the sulfuric acid acidic solution, which is the reaction starting solution, is adjusted to be 0.72 to 1.09 m ³ /t-Ni. hand,
so that the 50% particle size of the generated nickel sulfide is 50 to 80 μm,
A hydrometallurgical method for nickel oxide ore.

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