JP6724351B2 - How to remove sulfiding agent - Google Patents

Description

The present invention relates to a method for removing a sulfiding agent such as hydrogen sulfide gas dissolved in a solution.

As a method for efficiently recovering valuable substances such as nickel and cobalt from low nickel grade nickel oxide ore, there is a method called a high pressure acid leaching (HPAL) process as disclosed in Patent Document 1, for example. This method is a hydrometallurgical method based on high-temperature pressure leaching for recovering nickel from nickel oxide ore, which simplifies the leaching step and solid-liquid separation step, the amount of neutralizing agent consumed in the neutralization step, and the amount of starch. It is possible to provide a simple and highly efficient smelting method for the whole process by reducing the amount of water and repeatedly using water more efficiently.

Specifically, this hydrometallurgical method includes a leaching step in which sulfuric acid is added to a slurry of nickel oxide ore, and a stirring process is performed while pressurizing at a high temperature of 220° C. to 280° C. to form a leached slurry, and a leached slurry is formed. A solid-liquid separation step of obtaining a leaching solution containing nickel and cobalt and a leaching residue by multi-stage washing, and a neutralizing precipitate slurry containing trivalent iron by adding a neutralizing agent to the leaching solution and a mother liquor for nickel recovery. There is a neutralization step of forming and a sulfiding step of adding a sulfiding agent to the mother liquor to form a sulfide containing nickel and cobalt and a poor liquor.

In such a nickel oxide ore smelting method by the HPAL process, in order to recover nickel and cobalt from the sulfuric acid acidic solution, impurities such as slaked lime and limestone are added in the neutralization step to adjust the pH. Most of them can be separated, and then a sulfidizing agent such as hydrogen sulfide gas is added to precipitate nickel and cobalt sulfides, which are then separated from the post-sulfiding liquid, enabling efficient recovery of nickel and cobalt. it can. Then, by adding a neutralizing agent to the post-sulfurization liquid obtained after the sulfurization treatment in the sulfurization step, impurities such as manganese are separated and removed, and then discharged after being neutralized as waste water.

At this time, the sulfiding agent used for the sulfiding treatment may remain in the post-sulfiding liquid and cannot be discharged without removing it.

As a method for removing a sulfiding agent such as hydrogen sulfide dissolved in a sulfuric acid solution, various methods have been conventionally adopted. Specific methods include, for example, a method of aerating a sulfuric acid solution by aeration, a method of aerating under reduced pressure, a method of oxidizing hydrogen sulfide with an oxidizing agent to fix it as a sulfate, and further, an acid concentration of the sulfuric acid solution. Examples thereof include a method of increasing the solubility of hydrogen sulfide to lower it.

However, with these methods, it is difficult to completely separate hydrogen sulfide from a sulfuric acid solution, and there is a problem that costs such as equipment cost and operating material cost are high.

Specifically, the method of aerating by aeration requires equipment such as a blower, and the method of depressurizing and aerating requires a closed reaction tank and a vacuum pump. Further, in the method of adding and fixing an oxidizing agent such as hydrogen peroxide, it is necessary to pay attention to safety in handling and storing the oxidizing agent, and the operating cost is increased because the oxidizing agent itself is expensive. Further, in order to adjust the acid concentration of the sulfuric acid solution, the amount of sulfuric acid added is increased.

Furthermore, in many of these treatments, in order to reduce the solubility of hydrogen sulfide, basically hydrogen sulfide gas is further generated. Therefore, in order to remove the generated hydrogen sulfide gas, caustic soda or the like is removed. It is also necessary to install an exhaust gas treatment facility (scrubber) with alkali.

Further, Patent Document 2 discloses a technique of decomposing hydrogen sulfide dissolved in a solution by using iron ions and sulfuric acid. This method is a method for easily and economically oxidatively fixing and removing hydrogen sulfide from a solution in which hydrogen sulfide is dissolved, and specifically, a trivalent Fe compound is added to a solution containing hydrogen sulfide. When hydrogen sulfide and trivalent Fe compound are reacted with each other at pH of 3 or less and redox potential (ORP) of 0 mV (Ag/AgCl electrode reference) or more, hydrogen sulfide dissolved in the solution is converted into sulfur. It is to fix the shape. The Fe compound is iron hydroxide, and it is preferable that the concentration of Fe in the solution is 1 g/L or more.

In the method shown in Patent Document 2, although hydrogen sulfide in the solution can be efficiently removed, it is necessary to add a large amount of iron, and it takes time and cost to prepare sulfuric acid to be added. There is.

These methods can be industrially implemented in small-scale equipment such as a detoxification tower in an ordinary factory, but on the other hand, by leaching nickel or cobalt from the above-mentioned nickel oxide ore by the HPAL method and then sulfiding it. Since a large amount of sulfuric acid solution needs to be handled in the recovery process, it is necessary to remove dilute dissolved hydrogen sulfide from the large amount of sulfuric acid solution.

Therefore, there is a need for a method for effectively removing dilute hydrogen sulfide and other sulfiding agents from a large amount of solution more efficiently and at low cost.

JP, 2005-350766, A JP, 2004-89915, A

The present invention has been proposed in view of such circumstances, and provides a method for removing a sulfiding agent that is more efficient than conventional methods and effectively removes a diluting sulfiding agent such as dilute hydrogen sulfide from a large amount of a solution. The purpose is to do.

The present inventors have earnestly studied to solve the above-mentioned problems. As a result, by adding an iron compound to the post-sulfurization solution in which the sulfurization agent is dissolved and adjusting the pH of the solution to a predetermined range by adding a sulfuric acid solution, the sulfurization agent in the post-sulfurization solution is solidified. It was found that the sulfur can be generated and recovered as sulfur, and the present invention has been completed.

(1) The first invention of the present invention is to add a sulfidizing agent to a solution containing nickel, and to add sulfur to the post-sulfuration solution obtained by the treatment of sulfurizing the nickel to separate into a sulfide and a post-sulfurization solution. A method for removing the remaining sulfiding agent, which comprises adding an iron compound to the post-sulfurization liquid and adding a sulfuric acid solution having a concentration of 0.05 normal to 36 normal to the post-sulfurization liquid having a pH of 0. It is a method of removing a sulfiding agent, which is added so as to be 3.0 or less and produces and recovers sulfur.

(2) A second invention of the present invention is the method for removing a sulfidizing agent according to the first invention, wherein the nickel-containing solution is a leachate obtained by acid leaching nickel oxide ore under high temperature and high pressure. Is.

(3) A third invention of the present invention is the method for removing a sulfiding agent according to the first invention, wherein an iron compound in which iron exists in a trivalent form is used as the iron compound.

(4) A fourth invention of the present invention is the same as the first invention, wherein an iron compound in which iron exists in a divalent form is added as the iron compound, and an oxidizing agent is further added to the post-sulfurization liquid. A method for removing a sulfiding agent, which comprises oxidizing iron of the iron compound into a trivalent form.

(5) The fifth invention of the present invention is the sulfurizing agent according to the first invention, wherein the iron compound is a starch obtained by adding an oxidizing agent and an alkali to a solution after recovering the sulfur. Is the removal method.

(6) The sixth invention of the present invention is, in the first invention, iron hydroxide is used as the iron compound, and the iron concentration in the post-sulfuration liquid is 0.5 g/L or more and 3.0 g/L or less. It is a method of removing the sulfiding agent, which is added so that

(7) A seventh invention of the present invention is, in the first invention, wherein the solution containing nickel is a leachate obtained by acid leaching nickel oxide ore under high temperature and high pressure, and as the iron compound, It is a method for removing a sulfiding agent, which uses an leaching residue produced by acid leaching of the nickel oxide ore and adds it so that the iron concentration in the post-sulfiding liquid is 15 g/L or more and 20 g/L or less.

(8) The eighth invention of the present invention is, in the first invention, wherein the solution containing nickel is a leachate obtained by acid leaching nickel oxide ore containing scandium under high temperature and high pressure, As a sulfuric acid solution, a sulfuric acid solution is removed by using the sulfuric acid solution which has been passed through the chelate resin and then discharged after passing the post-sulfurization liquid through the chelate resin.

(9) A ninth aspect of the present invention is the method for removing a sulfiding agent according to any one of the first to eighth aspects, wherein the sulfiding agent is hydrogen sulfide gas.

According to the present invention, a diluting agent such as dilute hydrogen sulfide can be effectively removed from a large amount of solution more efficiently than before.

Further, for example, by using the leaching residue generated in the hydrometallurgical process of nickel oxide ore as the iron compound, and by using the post-sulfurization liquid obtained in the hydrometallurgical process of nickel oxide ore as the sulfuric acid solution. By using the sulfuric acid solution discharged in the process of recovering scandium, it is possible to operate the entire process extremely efficiently while preventing an increase in processing cost.

It is a figure which shows an example of the flow of the hydrometallurgical process of nickel oxide ore. It is a figure which shows a series of flows including the removal method of a sulfiding agent.

Hereinafter, specific embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications can be made 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. Overview ≫
The method for removing the sulfiding agent according to the present embodiment is a method for removing the sulfiding agent such as dissolved hydrogen sulfide gas from a solution such as a sulfuric acid acidic solution. Specifically, a method of adding a sulfiding agent to a solution containing nickel, and removing the sulfiding agent remaining in the post-sulfurization liquid obtained by the treatment of sulfurizing the nickel to separate it into a sulfide and a post-sulfurization liquid. Is.

Then, in this method for removing a sulfiding agent, an iron compound is added to a post-sulfiding solution in which the sulfiding agent is dissolved, and a sulfuric acid solution having a concentration of 0.05 N or more and 36 N or less is added to the post-sulfiding liquid pH. Is added so that the value is 0 or more and 3.0 or less.

<Sulfurization treatment of a solution containing nickel>
Here, prior to a detailed description of the method for removing the sulfiding agent remaining in the post-sulfiding liquid, a sulfiding agent is added to a solution containing nickel to sulphate nickel to generate a sulfide and a post-sulfiding liquid. The processing to be performed will be described.

For example, in the hydrometallurgical process of nickel oxide ore, the slurry of the raw material nickel oxide ore is subjected to leaching treatment using an acid such as sulfuric acid under high temperature and high pressure, and the obtained leachate is neutralized. After the impurities are removed by performing the treatment, a sulfide containing nickel is generated by adding a sulfiding agent such as hydrogen sulfide gas to the leachate and sulfiding the leachate.

More specifically, FIG. 1 is a process diagram showing a flow of a hydrometallurgical process of nickel oxide ore. This hydrometallurgical process includes a leaching step S11 in which nickel oxide ore is leached with sulfuric acid or the like under high temperature and high pressure to obtain a leached liquid, and a neutralized precipitate containing impurities by adding a neutralizing agent to the leached liquid and a neutralized liquid. And a sulfurization step S13 in which a sulfidizing agent is added to the post-neutralization liquid to obtain a nickel sulfide and a post-sulfurization liquid. Furthermore, this hydrometallurgical process has a final neutralization step S14 for recovering and detoxifying the leaching residue generated in the leaching step S11 and the post-sulfurization liquid discharged in the sulfurization step S13. In the method for removing a sulfiding agent according to the present embodiment, for example, a post-sulfiding liquid obtained by such a hydrometallurgical process of nickel oxide ore is treated, and the sulfiding agent remaining in the post-sulfiding liquid is removed. ..

(1) Leaching Step In the leaching step S11, an acid such as sulfuric acid is added to the slurry of nickel oxide ore by using a high temperature pressure vessel (autoclave) or the like and stirred at a temperature of 220° C. to 280° C. while stirring. It is a step of performing a treatment to form a leached slurry composed of a leaching liquid and a leaching residue.

Here, examples of nickel oxide ores include so-called laterite ores such as limonite ores and saprolite ores. The nickel content of the laterite ore is usually 0.8 to 2.5% by weight, and it is contained as a hydroxide or magnesia silicate (magnesium silicate) mineral. Moreover, scandium is contained in these nickel oxide ores.

In the leaching step S11, the leaching slurry composed of the obtained leaching liquid and the leaching residue is washed, and the leaching liquid containing nickel, cobalt, scandium and the like is solid-liquid separated into the leaching residue which is hematite. In this solid-liquid separation treatment, for example, after the leaching slurry is mixed with the cleaning liquid, the solid-liquid separation treatment is carried out by a solid-liquid separation equipment such as a thickener using the coagulant supplied from the coagulant supply equipment. Specifically, first, the leach slurry is diluted with the cleaning liquid, and then the leach residue in the slurry is concentrated as a thickener sediment.

(2) Neutralization step In the neutralization step S12, a neutralizing agent is added to the leachate obtained in the above-mentioned leach step S11 to adjust the pH, and the neutralized precipitate containing the impurity element and the post-neutralization solution are added. It is a process of obtaining. By the neutralization treatment in the neutralization step S12, valuable metals such as nickel, cobalt and scandium are contained in the solution after neutralization, and most of impurities such as iron and aluminum become neutralized precipitates.

As the neutralizing agent, conventionally known ones can be used, and examples thereof include calcium carbonate, slaked lime and sodium hydroxide.

In the neutralization treatment in the neutralization step S12, it is preferable to adjust the pH to the range of 1 to 4 while suppressing the oxidation of the separated leachate, and to adjust the pH to the range of 1.5 to 2.5. Is more preferable. If the pH is less than 1, neutralization may be insufficient and the neutralized precipitate and the post-neutralization liquid may not be separated. On the other hand, when the pH exceeds 4, not only impurities such as aluminum but also valuable metals such as nickel and scandium may be contained in the neutralized precipitate.

(3) Sulfidation Step The sulfidation step S13 is a step of adding a sulfidizing agent to the post-neutralization solution obtained in the above-mentioned neutralization step S12 to obtain a nickel sulfide and a post-sulfidation solution. By the sulfurization treatment in the sulfurization step S13, nickel, cobalt, zinc and the like become sulfides, and scandium and the like are contained in the post-sulfurization liquid.

Specifically, in the sulfurization step S13, a sulfurizing agent is added to the obtained post-neutralization liquid to cause a sulfurization reaction in which nickel or the like contained in the post-neutralization liquid is sulfurized into a sulfide form. As a result, a sulfide containing nickel and cobalt having a small amount of impurity components (nickel/cobalt mixed sulfide) and a post-sulfiding liquid in which the nickel concentration is stabilized at a low level are generated.

As the sulfiding agent, for example, hydrogen sulfide gas, sodium sulfide, sodium hydrosulfide sulfide or the like can be used, and among them, hydrogen sulfide gas is particularly preferable from the viewpoint of easy handling and cost.

In this sulfurization treatment, the nickel-cobalt mixed sulfide slurry is separated and collected from the bottom of the thickener by sedimentation separation treatment of the nickel-cobalt mixed sulfide using a sedimentation separation device such as thickener, while the sulfurization which is an aqueous solution component is performed. The after liquid is overflowed and collected.

(4) Final Neutralization Step In the final neutralization step S14, an emission standard is set for the post-sulfurization solution generated in the sulfurization step S13 described above, that is, for the post-sulfurization solution containing impurity elements such as iron, magnesium and manganese. Neutralization treatment (detoxification treatment) is performed to adjust to a predetermined pH range to be satisfied. Further, in the final neutralization step S14, the leaching residue generated in the leaching step S11 can also be treated together.

The method of detoxification treatment in the final neutralization step S14, that is, the method of adjusting the pH is not particularly limited, but, for example, by adding a neutralizing agent such as calcium carbonate (limestone) slurry or calcium hydroxide (slaked lime) slurry. It can be adjusted within a predetermined range.

In the neutralization process in the final neutralization step S14, the iron contained in the post-sulfurization liquid is fixed and separated in the form of iron hydroxide (Fe(OH) ₃ ).

<<2. Detailed explanation of the method for removing sulfidizing agents>>
Now, in the hydrometallurgical process of this nickel oxide ore, the sulfidizing agent added for causing the sulfidation reaction may remain in the post-sulfurization liquid generated through the sulfurization treatment in the sulfurization step S13. The post-sulfurization liquid generated by the sulfurization treatment is transferred to the final neutralization step S14 as described above, and the components such as magnesium and manganese are removed by performing the detoxification treatment on the solution, and the drainage standard is satisfied. Is discharged to the outside of the system. However, when the sulfiding agent remains in the liquid after sulfiding, it cannot be discharged to the outside of the system unless the removing treatment of the sulfiding agent is performed.

In the method for removing a sulfiding agent according to the present embodiment, the iron compound is added to the post-sulfidation liquid in which the sulfiding agent is dissolved, and the concentration is 0.05 N (N) or more and 36 N (N) or less. The sulfuric acid solution is added so that the pH of the post-sulfurization solution becomes 0 or more and 3.0 or less, whereby the sulfur is deposited and recovered in the post-sulfurization solution and recovered. That is, the dissolved sulfurizing agent such as hydrogen sulfide is fixed and recovered as solid sulfur, and is removed from the post-sulfurized liquid.

FIG. 2 is a diagram showing a series of flows including a method for removing a sulfiding agent. As shown in FIG. 2, the post-sulphurization liquid that is the target of the sulfurizing agent removal treatment is hydrogen sulfide gas or the like against the nickel-containing solution such as the leachate produced in the hydrometallurgical process of nickel oxide ore as described above. It can be obtained by sulfurizing (sulfurization treatment) using the sulfurizing agent of (1) and solid-liquid separating the obtained nickel sulfide. Then, in the treatment for removing the sulfiding agent, an iron compound is added to the post-sulfiding solution and a sulfuric acid solution is added to bring the pH to a predetermined range, so that the sulfiding agent in the post-sulfiding solution is mixed with sulfur (S ) And separate and collect. Note that FIG. 2 shows an example of a mode in which diluted sulfuric acid discharged from the scandium recovery process is used as the sulfuric acid solution added to the post-sulfurization liquid.

More specifically, in this method for removing a sulfiding agent, an iron compound is added to the post-sulfidation liquid in which the sulfiding agent is dissolved so as to have the above-mentioned iron concentration, and then the redox potential (ORP) is set to 0 mV ( (Silver/silver chloride electrode standard) or higher, and at the same time, sulfuric acid is added so that the pH of this solution is 0 or higher and 3.0 or lower and the sulfuric acid concentration described above is achieved.

In this method for removing the sulfurizing agent, a trivalent iron compound dissolved in the post-sulfurization liquid is used to oxidize and fix the hydrogen sulfide dissolved in the post-sulfurization liquid to release toxic hydrogen sulfide gas into the atmosphere. It is fixed and removed as sulfur without doing so, and for example, a reaction as shown in the following reaction formula occurs. In the reaction example shown in this reaction formula, hydrogen sulfide (H ₂ S) gas is used as the sulfiding agent, and iron hydroxide containing trivalent iron is used as the iron compound.
2Fe(OH) ₃ +3H ₂ SO ₄ ⇒ Fe ₂ (SO ₄ ) ₃ +6H ₂ O
Fe ₂ (SO ₄ ) ₃ +H ₂ S ⇒ 2FeSO ₄ +H ₂ SO ₄ +S

The term "fixation" used herein means that the compound is converted into a stable form, and in the method for removing a sulfiding agent according to the present embodiment, the sulfiding agent such as hydrogen sulfide gas reacts with sulfur of the carrier by the reaction. It is converted to a stable form (S), and this simple substance of sulfur is precipitated and removed.

The redox potential (ORP) when an iron compound and a sulfuric acid solution are added to the post-sulfurization liquid and reacted is required to be 0 mV or more when measured using a silver/silver chloride electrode as a reference electrode. Is. The redox potential at the time of this reaction shows the progress of the reaction. If the redox potential is smaller than 0 mV, the fixing reaction of the sulfiding agent as described above does not proceed. The redox potential can be controlled by the amount of the iron compound added.

The reaction time of the reaction caused by adding the iron compound and the sulfuric acid solution is preferably adjusted appropriately depending on the treatment amount, but is preferably 30 minutes or more, whereby the sulfiding agent is almost completely fixed. Can be removed.

[Iron compound]
As the iron compound, an iron compound in which iron exists in a trivalent form is preferably used, and iron hydroxide having excellent reactivity is particularly preferably used. As the iron compound, an iron compound in which iron exists in a divalent form may be used. In this case, after the iron compound containing divalent iron is added to the post-sulfurization liquid, for example, oxidation of air or the like is performed. The agent is added to the solution to oxidize to the trivalent form. However, it is more preferable to use an iron compound in which iron exists in a trivalent form from the viewpoint of eliminating the need for such an oxidation treatment after addition.

When iron hydroxide, for example, is used as the iron compound, the amount of iron added is such that the iron concentration in the post-sulfiding liquid is in the range of 0.5 g/L or more and 3.0 g/L or less. Further, it is preferable that the iron concentration is added in a range of 1.0 g/L or more and 2.0 g/L or less. When the addition amount is such that the iron concentration in the solution is less than 0.5 g/L, the sulfiding agent dissolved in the post-sulfiding liquid cannot be sufficiently fixed as sulfur. On the other hand, when the iron concentration in the solution is added so as to exceed 3.0 g/L, the effect of fixing the sulfiding agent is not further improved, and the amount of the starch increases in the subsequent wastewater treatment, etc. Inefficient operation is not possible.

Further, as the iron compound, the leaching residue generated in the leaching step S11 in the hydrometallurgical process of the nickel oxide ore described above can be used. That is, a leaching residue obtained by solid-liquid separation from a leaching slurry produced by acid leaching with sulfuric acid or the like to a nickel oxide ore slurry under conditions of high temperature and high pressure can be used. The leaching residue is an iron compound whose main component is hematite (Fe ₂ O ₃ ) and which contains trivalent iron.

Here, hematite is a more stable compound than iron hydroxide and has poor reactivity. Therefore, as the amount of hematite added (the amount of hematite to be added), it is necessary to add more than the above-mentioned iron hydroxide, and the sulfuric acid solution described below is also added in excess to adjust the pH of the solution to It is necessary to reduce the iron content more than when iron is added as an iron compound. Specifically, even if it is iron hydroxide or hematite, by adding a certain amount or more of the amount of iron in the liquid after sulfidation, the sulfiding agent in the solution can be fixed, but with the iron compound When comparing the concentrations of the sulfuric acid solutions to be added, in the case of iron hydroxide, if the amount of iron in the solution is 0.5 g/L or more, the concentration of the diluted sulfuric acid is 0.05 N or so. Even if it is a solution or a concentrated sulfuric acid solution of about 36 N, the sulfiding agent can be effectively fixed. However, when hematite is used, it is necessary to add it so that the amount of iron in the solution is in the range of 15 g/L or more and 20 g/L or less.

In addition, as the iron compound, an iron precipitate (iron precipitate) produced through the final neutralization step S14 in the same hydrometallurgical process of nickel oxide ore can be used. In the final neutralization step S14, as described above, the post-sulfurization liquid containing impurities such as iron, magnesium and manganese is subjected to neutralization treatment with a neutralizing agent such as calcium carbonate or slaked lime. Iron contained in the liquid is separated and removed as iron starch (mainly in the form of iron hydroxide). The iron starch produced by such neutralization treatment can be recovered and used as an iron compound. The final neutralization step S14 can be provided after the removal of the sulfiding agent from the post-sulfiding liquid.

As described above, when the post-sulfidation liquid produced through the hydrometallurgical process of nickel oxide ore is subjected to the removal treatment of the sulfiding agent, the leaching residue produced in the leaching step S11 in the upstream process of the same process and the final neutralization By using the iron starch produced in step S14 as a processing raw material, it is not necessary to prepare a new iron compound, and it is possible to perform an extremely efficient operation as a whole process while preventing an increase in processing cost. .. In addition, there is an advantage that it can reuse effectively what was conventionally disposed of.

[Sulfuric acid solution]
It is considered that concentrated sulfuric acid having a high concentration is preferably used as the sulfuric acid solution, but the concentration is not particularly limited. However, in the case of an extremely low concentration sulfuric acid solution, the above-mentioned reaction time for immobilizing the sulfiding agent as sulfur becomes long. Further, when a low-concentration sulfuric acid solution is used, the amount of sulfuric acid to be added increases, and equipment such as a tank and a pump inevitably becomes large.

Specifically, the concentration of the sulfuric acid solution is preferably 0.05N or more. The upper limit of the concentration of sulfuric acid is not particularly limited, and may be, for example, 36 N or less.

The amount of the sulfuric acid solution added varies depending on the concentration of the sulfuric acid used, but is added so that the pH of the post-sulfurization liquid is in the range of 0 to 3.0, preferably 1.0 to 3. It is added in a range of 0 or less, more preferably 1.0 or more and 1.8 or less. In this way, by adjusting the pH of the post-sulfurization solution within the range of 0 or more and 3 or less by adding the sulfuric acid solution, the dissolution of the added iron can be promoted and the reaction rate can be increased.

Although it is possible to react even if the pH of the post-sulfurization liquid is lowered by increasing the sulfuric acid concentration, when the pH is lowered to less than 0, the acidity of the solution becomes too strong and the solubility of hydrogen sulfide is increased. Will decrease.

Here, as the sulfuric acid solution, as shown in the example of the process diagram of FIG. 2, for example, the post-sulfurization liquid produced in the sulfurization process S13 in the hydrometallurgical process of nickel oxide ore is used as a raw material and is contained in the post-sulfurization liquid. A sulfuric acid solution discharged in the process of recovering scandium (scandium recovery process) can be used.

The scandium recovery process is for purifying and recovering scandium, which is a target metal, using a post-sulfurization liquid containing scandium as a raw material. Specifically, for example, the post-sulfurization liquid is subjected to a treatment such as ion exchange using a chelate resin to roughly separate the impurity elements, and the scandium-containing solution obtained from the ion exchange treatment (scandium eluent Is subjected to a solvent extraction treatment or the like to be concentrated, and scandium is recovered from the resulting solution in the form of scandium oxide or the like.

In the scandium recovery process, in order to recover a small amount of low-concentration scandium, the operation of adsorbing scandium on the chelate resin and concentrating it is performed as described above. At this time, the scandium adsorbed on the chelate resin is eluted A sulfuric acid solution (diluted sulfuric acid solution) is used in the operation and the operation of washing the chelate resin. Conventionally, the sulfuric acid solution discharged through such an operation had to be discarded. However, for example, the sulfuric acid solution after washing used for washing the chelate resin has a concentration of about 0.5 N, and iron present in a trivalent form has a proportion of about 0.05 g/L to 0.15 g/L. include.

From this, by recovering the sulfuric acid solution discharged from the scandium recovery process and using it as a processing raw material for the removal processing of the sulfiding agent contained in the post-sulfurization liquid, it is not necessary to prepare a new sulfuric acid solution, and the processing cost is reduced. It is possible to operate the entire process extremely efficiently while preventing the increase. Further, there is an advantage that the sulfuric acid solution, which has conventionally been disposed only, can be effectively utilized again.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[Example 1]
As shown in the hydrometallurgical process of nickel oxide ore in FIG. 1, a slurry of nickel oxide ore is charged into an autoclave and subjected to a leaching process using sulfuric acid under high temperature and high pressure to obtain a leachate and a leach residue (hematite, Fe A leaching slurry containing ₂ O ₃ ) was obtained (leaching step), and hydrogen sulfide gas was added as a sulfiding agent to the leaching liquid (solution containing nickel) obtained by solid-liquid separation to perform sulfide treatment. (Sulfiding step). By the sulfurization reaction in this sulfurization step, nickel in the leachate was sulfurized to form a sulfide. The produced sulfide was recovered by solid-liquid separating the slurry after the sulfurization treatment with a thickener.

On the other hand, when the sulfuric acid acidic solution after separation and recovery of the sulfide, that is, the post-sulfurization solution was separately recovered and analyzed, hydrogen sulfide used for the sulfurization treatment remained. Table 1 below shows measured values of the concentration of dissolved hydrogen sulfide, pH, and oxidation-reduction potential (ORP).

Therefore, a treatment for removing the sulfiding agent dissolved in the post-sulfiding liquid was performed. In the treatment for removing the sulfiding agent, the sulfur compound was removed by adding an iron compound and diluted sulfuric acid to the post-sulfiding liquid and immobilizing hydrogen sulfide dissolved in the post-sulfiding liquid as sulfur.

More specifically, 500 mL of a solution after sulfidation, which is an acidic sulfuric acid solution, is placed in a 1-liter beaker, and iron hydroxide (Fe(OH) ₃ ) containing trivalent iron as an iron compound (water content 40%, iron grade 10%) was added so that the iron concentration in the solution would be 0.5 g/L. Next, a sulfuric acid solution prepared by diluting 36N sulfuric acid with a concentration of 5N was added to the solution to adjust the pH of the solution to a range of 1.0 to 2.0 (average 1.6). ..

Here, as the iron compound, in the hydrometallurgical process of the nickel oxide ore described above, iron hydroxide generated by performing a detoxification treatment (final neutralization step) on the post-sulfurization liquid generated after the sulfurization treatment It was collected and used.

Further, as the sulfuric acid solution, the sulfuric acid solution produced in the scandium recovery process using the post-sulfurization liquid after the sulfurization treatment was used. That is, a sulfuric acid solution was used in which the post-sulfurization liquid was passed through the chelate resin and then passed through the chelate resin and discharged.

Then, the mixture was placed in a reaction vessel having a structure in which air was sealed so as not to be entrapped, and stirred for 30 minutes while stirring with a stirrer while maintaining the reaction temperature of 50° C. to 60° C. with the preset temperature of the reaction vessel set to 55° C. ..

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. The measurement results are shown in Table 2, which was less than the lower limit of analysis of 1 mg/L, and hydrogen sulfide used as the sulfiding agent was removed.

[Example 2]
In Example 2, the treatment was performed in the same manner as in Example 1 except that a sulfuric acid solution diluted to a concentration of 10 N was added as a sulfuric acid solution added to the post-sulfurization liquid.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. The measurement results are shown in Table 2, which was less than the lower limit of analysis of 1 mg/L, and hydrogen sulfide used as the sulfiding agent was removed.

[Example 3]
In Example 3, the treatment was performed in the same manner as in Example 1 except that a sulfuric acid solution diluted to a concentration of 0.1 N was added as a sulfuric acid solution added to the post-sulfurization liquid.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. The measurement results are shown in Table 2, which was less than the lower limit of analysis of 1 mg/L, and hydrogen sulfide used as the sulfiding agent was removed.

[Example 4]
In Example 4, the treatment was performed in the same manner as in Example 1 except that a sulfuric acid solution diluted to a concentration of 0.05 N was added as a sulfuric acid solution added to the post-sulfurization liquid.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. The measurement results are shown in Table 2, which was less than the lower limit of analysis of 1 mg/L, and hydrogen sulfide used as the sulfiding agent was removed.

[Example 5]
Example 5 was treated in the same manner as Example 1 except that trivalent iron hydroxide was added so that the iron concentration in the solution was 1.0 g/L.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. The measurement results are shown in Table 2, which was less than the lower limit of analysis of 1 mg/L, and hydrogen sulfide used as the sulfiding agent was removed.

[Example 6]
In Example 6, the treatment was performed in the same manner as in Example 1 except that concentrated sulfuric acid having a concentration of 36 N was added without dilution as a sulfuric acid solution added to the post-sulfurization liquid.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. The measurement results are shown in Table 2, which was less than the lower limit of analysis of 1 mg/L, and hydrogen sulfide used as the sulfiding agent was removed.

[Examples 7 and 8]
As the iron compound, hematite (moisture content 30%, iron quality 50%) produced in the leaching step in the hydrometallurgical process was used, and was added so that the iron concentration in the liquid after sulfidation was 17 g/L. Next, a sulfuric acid solution having a concentration of 5N (Example 7) and a concentration of 0.01N (Example 8) diluted with sulfuric acid having a concentration of 36N was added to the solution.

Then, the mixture was placed in a reaction tank having a structure sealed so as not to entrap air, and stirred with a stirrer while maintaining the reaction temperature at 50°C to 60°C and the reaction pH at 1.0 to 2.0. Let react for minutes.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in each filtrate was measured. Table 2 shows the measurement results. In each of Example 7 and Example 8, the analysis lower limit was less than 1 mg/L, and the hydrogen sulfide used as the sulfiding agent was removed.

[Example 9]
As an iron compound, divalent form of iron hydroxide (Fe(OH) ₂ ) is added to the post-sulfurization liquid, and the air is blown into the post-sulfurization liquid while stirring to oxidize the iron ions to trivalent. The treatment was performed in the same manner as in Example 1 except that the reaction was performed.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. The measurement results are shown in Table 2, which was less than the lower limit of analysis of 1 mg/L, and hydrogen sulfide used as the sulfiding agent was removed.

[Comparative Example 1]
In Comparative Example 1, the same treatment as in Example 1 was carried out except that a sulfuric acid solution diluted to a concentration of 0.05 N was added as a sulfuric acid solution to be added to the post-sulfurization liquid.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. Table 2 shows the measurement results. Hydrogen sulfide remained in the solution at a rate of 5 mg/L.

[Comparative example 2]
In Comparative Example 2, hematite produced in the leaching step in the hydrometallurgical process was used as the iron compound, and was added so that the iron concentration in the liquid after sulfurization was 10 g/L. Further, as a sulfuric acid solution, a sulfuric acid solution diluted to a concentration of 5 N was added. Except for these matters, the same treatment as in Example 7 was carried out.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. Table 2 shows the measurement results. Hydrogen sulfide remained in the solution at a rate of 10 mg/L.

[Comparative Example 3]
In Comparative Example 3, trivalent iron hydroxide was added so that the iron concentration in the solution would be 0.1 g/L, and concentrated sulfuric acid having a concentration of 36 N without dilution was used as a sulfuric acid solution to be added to the post-sulfurization solution. It processed like Example 1 except having added.

After completion of the reaction, filtration treatment was performed to collect the filtrate, and the hydrogen sulfide concentration in the filtrate was measured. Table 2 shows the measurement results. Hydrogen sulfide remained in the solution at a rate of 5 mg/L.

In this way, by controlling the redox potential during the reaction and ensuring the necessary reaction time, by adding an arbitrary iron compound and adding a sulfuric acid solution having a concentration of 0.05 N or more and 36 N or less, Hydrogen sulfide, which is a sulfiding agent, can be effectively fixed and removed. On the other hand, when the iron concentration derived from the added iron compound is low, it is difficult to effectively fix hydrogen sulfide regardless of the concentration of the sulfuric acid solution.

Claims (7)

A method of adding a sulfiding agent to a solution containing nickel, and removing the sulfiding agent remaining in the post-sulfiding solution obtained by the treatment of sulfiding nickel to separate it into a sulfide and a post-sulfiding solution,
The solution containing nickel is a leachate obtained by acid leaching nickel oxide ore containing scandium under high temperature and high pressure,
An iron compound is added to the post-sulfurization liquid, and the sulfuric acid solution is discharged by passing the post-sulfuration liquid through a chelate resin and then passing through the chelate resin. A method for removing a sulfiding agent, which comprises adding a sulfuric acid solution of 36 N or less so that the pH of the post-sulfiding liquid is 0 or more and 3.0 or less to generate and recover sulfur. The method for removing a sulfiding agent according to claim 1, wherein an iron compound in which iron exists in a trivalent form is used as the iron compound. As the iron compound, an iron compound in which iron exists in a divalent form is added,
The method for removing a sulfiding agent according to claim 1, further comprising adding an oxidizing agent to the post-sulfiding liquid to oxidize iron of the iron compound into a trivalent form. The method for removing a sulfurizing agent according to claim 1, wherein a starch obtained by adding an oxidizing agent and an alkali to a solution after recovering the sulfur is used as the iron compound. The method for removing a sulfiding agent according to claim 1, wherein iron hydroxide is used as the iron compound, and is added so that the iron concentration in the post-sulfidation liquid is 0.5 g/L or more and 3.0 g/L or less. The solution containing nickel is a leachate obtained by acid leaching nickel oxide ore under high temperature and high pressure,
The leaching residue produced by acid leaching the nickel oxide ore is used as the iron compound, and is added so that the iron concentration in the post-sulfuration liquid is 15 g/L or more and 20 g/L or less. Method of removing sulfiding agent. The sulfurizing agent, the method of removing the sulfur agent according to any one of claims 1 to 6 is hydrogen sulfide gas.

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