Processing method of nickel sulfide raw material and de-ironing method of iron-containing crude nickel chloride aqueous solution

Abstract

To enable an efficient removal of an iron ion and an arsenic ion from an iron / arsenic-containing nickel chloride aqueous solution obtained through a hydrometallurgical process using a nickel sulfide material including iron and arsenic.SOLUTION: A processing method of a nickel sulfide raw material including iron and arsenic includes: a cementation step of mixing a nickel sulfide raw material with a copper-containing and iron-containing crude nickel chloride aqueous solution containing a bivalent copper ion, and substituting and leaching nickel in the nickel sulfide raw material to obtain a cementation final solution with the copper ion removed and a cementation residue; and a chlorine leaching step of blowing a chlorine gas into a cementation residue slurry obtained by re-pulping the cementation residue to generate a chlorine leaching slurry to obtain a chlorine leachate and a chlorine reaching residue. In the chlorine leaching step, a hydrochloric acid is added to adjust a hydrochloric acid concentration of the chlorine leachate to be generated to adjust an iron-arsenic ratio (iron / arsenic) of an iron concentration and an arsenic concentration of the cementation final solution.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for treating a nickel sulfide raw material that contains nickel, cobalt, copper, and sulfur, and also contains iron and arsenic as impurities, and that makes it possible to control the distribution of iron and arsenic in a chlorine leaching residue when nickel and cobalt are leached from the nickel sulfide raw material with chlorine, and a method for removing iron from an iron-containing aqueous crude nickel chloride solution. [Background technology]

[0002] In the nickel hydrometallurgy process (hereinafter also referred to as the "MCLE process"), the raw material nickel matte or nickel-cobalt mixed sulfide (MS: mixed sulfide) is leached with chlorine, and the resulting leachate (chlorine leachate) is subjected to a purification process to remove impurities, and nickel and cobalt are recovered in the form of electrolytic nickel and electrolytic cobalt in an electrolytic process. The technology of the MCLE process is disclosed in, for example, Patent Document 1 and Patent Document 2.

[0003] As shown in FIG. 1, the chlorine leaching solution obtained from the chlorine leaching process is subjected to removal of excess copper in the copper removal electrolysis process provided between the cementation process and the cementation process, and impurities such as iron and arsenic are removed in the iron removal process, and then the solution is sent to the cobalt solvent extraction process. In the cobalt solvent extraction process, nickel and cobalt are separated by solvent extraction to obtain a crude nickel chloride solution (NiCl2) and a crude cobalt chloride solution (CoCl2). The crude nickel chloride solution is further purified by removing impurities in the solution purification process and sent to the nickel electrolysis process. Then, in the nickel electrolysis process, electrolytic nickel is produced by electrolytic winning. Meanwhile, the crude cobalt chloride solution is also further purified by removing impurities in the solution purification process and sent to the cobalt electrolysis process, where electrolytic winning is produced.

[0004] Now, the MCLE process has a cementation process as a process for removing copper ions, which are impurities contained in the chlorine leachate (copper-containing nickel chloride aqueous solution) obtained by chlorine leaching. In the cementation process, the oxidizing power of the divalent copper ions contained in the chlorine leachate is used to leach nickel and cobalt from the nickel matte and MS (hereinafter, these may be collectively referred to as "nickel sulfide raw material"), and the reducing power of the nickel matte and MS is used to distribute the copper ions and silver ions contained in the chlorine leachate to the solid side and remove them.

[0005] As described above, impurities such as iron ions and arsenic ions contained in the final cementation solution (nickel chloride aqueous solution from which copper ions have been removed) obtained through the cementation process are removed in the iron removal process. Regarding arsenic in the aqueous solution, it is converted into arsenate ions (AsO4 3- ), arsenite ion (AsO 2- ), arsenic ion (As 3+ ), but in this specification, ions of various valencies, including oxoacid ions, will be collectively referred to as "arsenic ions."

[0006] The iron removal process is carried out in an iron removal facility equipped with a total of n reaction tanks (n is an integer of 3 or more) connected in series, and consists of a process in which chlorine and carbonate are added to an aqueous nickel chloride solution containing iron ions and arsenic ions (an aqueous iron-containing nickel chloride solution containing arsenic) to oxidize and neutralize the iron ions and arsenic ions contained in the aqueous solution, and a process in which the resulting slurry is subjected to solid-liquid separation.

[0007] In particular, since it is widely known that arsenic ions are precipitated by coprecipitation with iron ions, the content ratio of iron ions to arsenic ions is an extremely important reaction indicator in the oxidation neutralization reaction. In the iron removal process, it is desired to reduce the iron ion concentration in the process liquid after the reaction (final iron removal liquid) to a low concentration of 0.01 g / L or less and the arsenic ion concentration to 0.001 g / L or less. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2018-3104 A [Patent Document 2] JP 2019-81920 A Summary of the Invention [Problem to be solved by the invention]

[0009] The nickel sulfide raw material to be treated in the MCLE process is processed using raw materials from various sources, and depending on the raw material treatment configuration, the load of various impurities may increase, and the amount of iron and arsenic to be removed may also increase. If you want to reduce the concentration of impurities in the nickel chloride solution to the target value, it is necessary to maintain a high content ratio of iron ions to arsenic ions in the iron-containing crude nickel chloride solution (iron-containing arsenic nickel chloride solution) to be subjected to the iron removal process.

[0010] However, since the distribution of iron and arsenic contained in the nickel sulfide raw material to the leachate and leach residue after the chlorine leaching process varies depending on the reaction conditions of the chlorine leaching, there may be a difference between the iron content relative to arsenic in the raw material composition (iron-arsenic ratio) and that in the deironization process. In particular, if the iron-arsenic ratio decreases, it may become difficult to reduce the arsenic ion to the target value.

[0011] The present invention has been proposed in view of the above circumstances, and has an object to provide a method that enables efficient removal of iron ions and arsenic ions from an aqueous solution of iron-containing arsenic chloride nickel obtained in a hydrometallurgical process using nickel sulfide containing iron and arsenic as impurities as a raw material, by adjusting the iron-arsenic ratio in the aqueous solution of iron-containing arsenic chloride nickel. [Means for solving the problem]

[0012] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that in a raw material treatment process including a cementation step of removing copper ions from a copper-containing, iron-containing crude nickel chloride aqueous solution containing divalent copper ions, and a chlorine leaching step of obtaining a chlorine leachate by chlorine leaching a cementation residue slurry, and repeating the chlorine leachate obtained as a copper-containing, iron-containing crude nickel chloride aqueous solution, by adding hydrochloric acid in the chlorine leaching step and adjusting the hydrochloric acid concentration of the chlorine leachate produced, and adjusting the iron-arsenic ratio (iron / arsenic) between the iron concentration and the arsenic concentration in the cementation final solution, it is possible to efficiently remove iron ions and arsenic ions in the iron removal treatment of the cementation final solution obtained through the cementation step, and have completed the present invention.

[0013] (1) The first invention of the present invention is a method for treating a nickel sulfide raw material containing iron and arsenic as impurities, comprising a cementation step of mixing a copper-containing and ferrous crude nickel chloride aqueous solution containing divalent copper ions with a nickel sulfide raw material, and displacing and leaching nickel in the nickel sulfide raw material with the copper ions in the copper-containing and ferrous crude nickel chloride aqueous solution to generate a cementation slurry which is a mixture of the ferrous crude nickel chloride aqueous solution from which the copper ions have been removed and a precipitate containing copper sulfide, and separating the resulting cementation slurry into a cementation end liquid and a cementation residue by solid-liquid separation; and a cementation step of repulping the cementation residue to produce a cementation slurry. and a chlorine leaching step of forming a cementation residue slurry from the cementation residue, injecting chlorine gas into the cementation residue slurry to leach heavy metals in the cementation residue to produce a chlorine leached slurry, and separating the slurry into a chlorine leached solution and a chlorine leached residue by solid-liquid separation, and repeating the chlorine leachate as the copper-containing, iron-containing crude nickel chloride aqueous solution. In the chlorine leaching step, hydrochloric acid is added to adjust the hydrochloric acid concentration of the chlorine leachate produced, thereby adjusting the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the cementation final solution by the arsenic concentration.

[0014] (2) A second aspect of the present invention is the method for treating a nickel sulfide raw material according to the first aspect of the present invention, wherein in the chlorine leaching step, the hydrochloric acid concentration is adjusted so that the pH of the chlorine leaching solution is −0.1 to 0.1.

[0015] (3) A third aspect of the present invention is a method for deironizing an aqueous solution of iron-containing crude nickel chloride containing iron and arsenic as impurities, comprising, in addition to the raw material treatment process as defined in claim 1, a deironization step of oxidizing and neutralizing the cementation end liquid to cause the iron in the cementation end liquid to precipitate as a neutralized precipitate, and separating the cementation end liquid and the iron-deironized precipitate by solid-liquid separation, and in the chlorine leaching step, hydrochloric acid is added to adjust the hydrochloric acid concentration of the chlorine leaching solution produced, thereby adjusting the iron / arsenic ratio (iron / arsenic) obtained by dividing the iron concentration of the cementation end liquid by the arsenic concentration.

[0016] (4) A fourth aspect of the present invention is the method for deironizing an iron-containing crude nickel chloride aqueous solution according to the third aspect of the present invention, wherein, in the chlorine leaching step, when the iron-arsenic ratio (iron / arsenic) is to be increased, a hydrochloric acid concentration of the chlorine leaching solution is decreased, and when the iron-arsenic ratio (iron / arsenic) is to be decreased, a hydrochloric acid concentration of the chlorine leaching solution is increased.

[0017] (5) A fifth aspect of the present invention is the method for removing iron from an iron-containing crude nickel chloride aqueous solution according to the third or fourth aspect of the present invention, wherein in the chlorine leaching step, the hydrochloric acid concentration is adjusted so that the pH of the chlorine leaching solution is −0.1 to 0.1. Effect of the Invention

[0018] According to the present invention, it is possible to provide a method that enables efficient removal of iron ions and arsenic ions from an aqueous solution of iron-containing arsenic-nickel chloride. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a process diagram showing a schematic flow of a nickel hydrometallurgical process (MCLE process). [Diagram 2] FIG. 1 is a process diagram showing an example of a flow when the nickel sulfide raw material processing method is applied to processing in an MCLE process. [Diagram 3] FIG. 1 is a graph showing the correlation between the pH of the chlorine leaching solution obtained in the chlorine leaching step and the iron content (A) and arsenic content (B) in the chlorine leaching residue, and the iron and arsenic content ratio (iron / arsenic) (C) in the chlorine leaching solution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a specific embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiment, and various modifications are possible without departing from the gist of the present invention.

[0021] The method for processing a nickel sulfide raw material according to the present embodiment is a method for processing a nickel sulfide raw material containing iron and arsenic as impurities.

[0022] For example, the nickel sulfide raw material may be a raw material used as a raw material in a nickel hydrometallurgical process (MCLE process). Therefore, as described in detail below, the processing method can be applied to processing in the MCLE process, which includes a cementation step and a chlorine leaching step.

[0023] 2 is a process diagram showing an example of a flow when this processing method is applied to processing in an MCLE process. Specifically, the processing method for nickel sulfide raw material according to this embodiment includes a cementation step S1 in which a copper-containing, iron-containing crude nickel chloride aqueous solution containing divalent copper ions is mixed with a nickel sulfide raw material, and nickel in the nickel sulfide raw material is substituted and leached by the copper ions in the copper-containing, iron-containing crude nickel chloride aqueous solution to remove the copper ions in the aqueous solution, and a chlorine leaching step S2 in which the cementation residue is repulped to form a cementation residue slurry, and then chlorine gas is blown into the cementation residue slurry to leach heavy metals to obtain a chlorine leachate and a chlorine leachate residue, and the chlorine leachate is repeatedly converted into a copper-containing, iron-containing crude nickel chloride aqueous solution, which is a raw material processing process.

[0024] This treatment method is characterized in that in the chlorine leaching step, hydrochloric acid is added to adjust the hydrochloric acid concentration of the chlorine leaching solution produced through chlorine leaching, thereby adjusting the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the cementation end solution (iron-containing crude nickel chloride aqueous solution) by the arsenic concentration.

[0025] According to such a method for treating a nickel sulfide raw material, it is possible to provide a method that enables efficient removal of iron ions and arsenic ions contained in the cementation end liquid (iron-containing crude nickel chloride aqueous solution). From this, the method according to the present embodiment can also be defined as a method for removing iron from an iron-containing crude nickel chloride aqueous solution.

[0026] <1. Cementation process> In the cementation step S1, a copper-containing, iron-containing crude nickel chloride aqueous solution containing divalent copper ions is mixed with a nickel sulfide raw material to fix and remove the copper ions in the copper-containing, iron-containing crude nickel chloride aqueous solution.

[0027] Nickel sulfide raw materials contain iron and arsenic as impurities, and examples of the nickel sulfide raw materials include mixed sulfide (MS) containing nickel and cobalt produced by a hydrometallurgical process using nickel oxide ore as a raw material, and nickel matte produced by a nickel pyrometallurgical process.

[0028] More specifically, in the cementation step S1, a nickel sulfide raw material containing iron and arsenic as impurities is mixed with a copper-containing, iron-containing crude nickel chloride aqueous solution containing divalent copper ions, and the nickel in the nickel sulfide raw material is leached by substitution with the copper ions in the copper-containing, iron-containing crude nickel chloride aqueous solution, thereby immobilizing and removing the copper ions in the copper-containing, iron-containing crude nickel chloride aqueous solution. This cementation reaction produces a cementation slurry, which is a mixture of the iron-containing crude nickel chloride aqueous solution from which the copper ions have been removed and a precipitate containing copper sulfide produced by immobilizing the copper ions as sulfides.

[0029] The copper-containing, iron-containing crude nickel chloride aqueous solution containing divalent copper ions, which is mixed with the nickel sulfide raw material, is a chlorine leachate obtained through a chlorine leaching treatment in the chlorine leaching step S2 described below. Thus, the process in this treatment method is a raw material treatment process that is configured by repeatedly converting the chlorine leachate into a copper-containing, iron-containing crude nickel chloride aqueous solution.

[0030] In the cementation step S1, the produced cementation slurry is subjected to solid-liquid separation to obtain a cementation end liquid (iron-containing crude nickel chloride aqueous solution) and a cementation residue (a precipitate containing copper sulfide). The method of solid-liquid separation is not particularly limited, and can be performed by a well-known method such as a centrifuge or a filter press, and the precipitate of copper sulfide, which is the cementation residue, can be efficiently separated.

[0031] The cementation end solution obtained through the cementation step S1 is sent to a solution purification step including the iron removal step S3. As will be described in detail later, the iron removal step S3 removes iron, an impurity contained in the cementation end solution (iron-containing crude nickel chloride aqueous solution). Although the notation methods are different, Figures 1 and 2 are both flow diagrams of the electrolytic nickel production process (MCLE process), and the "iron removal step," "cobalt solvent extraction step," and "solution purification step" can all be considered as solution purification steps. For example, the "copper removal electrolysis step" shown in Figure 1 is omitted in Figure 2, and the <sulfur recovery> shown in Figure 2 is omitted in Figure 1.

[0032] On the other hand, the cementation residue containing the copper sulfide immobilized in the cementation step S1 is sent again to the chlorine leaching step S2 and subjected to chlorine leaching treatment.

[0033] <2. Chlorine leaching process> In the chlorine leaching step S2, the cementation residue produced in the above-mentioned cementation step S1 is repulped to form a slurry (cementation residue slurry), and then chlorine gas is blown into the cementation residue slurry to perform chlorine leaching. By this chlorine leaching treatment, heavy metals such as nickel and copper in the cementation residue are leached into an aqueous solution.

[0034] In the chlorine leaching step S2, the chlorine leaching slurry produced through the chlorine leaching treatment is subjected to solid-liquid separation to obtain a chlorine leaching solution and a chlorine leaching residue. As described above, the obtained chlorine leaching solution is a solution obtained by leaching heavy metals such as nickel and copper contained in the cementation residue into an aqueous solution. The chlorine leaching solution also contains iron. Therefore, the chlorine leaching solution is an aqueous solution of crude nickel chloride containing copper and iron.

[0035] The chlorine leaching process will now be described more specifically. In the chlorine leaching step S2, for example, reactions shown in the following formulas [1] to [3] occur. Cl2+2Cu + → 2Cl - +2Cu2+ [1] NiS+2Cu 2+ → Ni 2+ +S 0 +2Cu + [2] Cu2S+2Cu 2+ → 4Cu + +S 0 [3]

[0036] That is, in the chlorine leaching step S2, when the cementation residue slurry is pumped, metal components contained in the cementation residue, such as nickel sulfide (NiS) and copper sulfide (Cu2S), are oxidized and leached by "divalent copper ions" oxidized by chlorine gas. This produces a nickel chloride aqueous solution containing copper ions, which is the chlorine leaching solution. As shown in formula [1], it is estimated that oxidative leaching using divalent copper ions as electron carriers is carried out in the chlorine leaching step S2. In addition, NiS in formula [2] represents the main component of MS, and Cu2S in formula [3] represents the main component of the cementation residue.

[0037] The chlorine leaching solution produced in the chlorine leaching step S2 is repeatedly used as a copper-containing, iron-containing nickel chloride aqueous solution containing divalent copper ions, and is sent to the cementation step S1 as described above, where it is mixed with the nickel sulfide raw material and treated to precipitate and remove the copper ions. 0 The chlorine leaching residue, mainly composed of, remains in the solid phase.

[0038] Here, the sulfur S produced in the reactions shown in the above formulas [2] and [3] is 0 In the case of chlorine gas, a strong oxidation reaction occurs directly with chlorine gas, as shown in the following equation [4], producing sulfuric acid and hydrochloric acid. S 0 +3Cl2+4H2O → H2SO4+6HCl ···[4]

[0039] In chlorine leaching, the pH of the chlorine leaching solution decreases as these reactions proceed, but the final pH is essentially determined by the amount of sulfur contained in the nickel sulfide raw material and various other conditions.

[0040] On the other hand, as described above, the nickel sulfide raw material contains iron and arsenic as impurities, which are distributed to the chlorine leaching solution and chlorine leaching residue depending on the treatment conditions in the chlorine leaching step S2, etc. Regarding the behavior of iron and arsenic in chlorine leaching, when the pH is low, the distribution of both (iron, arsenic) into the chlorine leaching solution increases, but when the pH is high, the distribution into the chlorine leaching solution decreases, so that some of them remain as solids in the chlorine leaching residue.

[0041] Since the pH of the chlorine leachate is essentially unpredictable as described above, the distribution of iron and arsenic to the chlorine leachate and chlorine leach residue is also essentially unpredictable.

[0042] Therefore, in the method for treating nickel sulfide raw material according to the present embodiment, hydrochloric acid is added in the chlorine leaching step S2 to adjust the hydrochloric acid concentration of the chlorine leaching solution produced through the chlorine leaching. This adjusts the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration by the arsenic concentration in the final cementation solution (iron-arsenic-containing nickel chloride aqueous solution) obtained through the cementation step S1.

[0043] Specifically, when increasing the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration by the arsenic concentration in the cementation end solution, the hydrochloric acid concentration of the chlorine leaching solution is adjusted to decrease in the chlorine leaching step S2. On the other hand, when decreasing the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration by the arsenic concentration in the cementation end solution, the hydrochloric acid concentration of the chlorine leaching solution is adjusted to increase in the chlorine leaching step S2.

[0044] Preferably, the hydrochloric acid concentration of the chlorine leachate is adjusted by adding hydrochloric acid so that the pH of the resulting chlorine leachate is −0.1 to 0.1.

[0045] Fig. 3 is a graph showing the correlation between the pH of the chlorine leaching solution obtained in the chlorine leaching step S2 and the iron content (A), arsenic content (B), and the content ratio (iron / arsenic) (C) of iron and arsenic in the chlorine leaching residue. As shown in each graph in Fig. 3, the distribution rate of iron and arsenic to the chlorine leaching residue increases as the pH of the chlorine leaching solution increases. In particular, it can be seen that the distribution behavior of iron and arsenic can be stabilized within a certain range by adjusting the hydrochloric acid concentration so that the pH of the chlorine leaching solution falls within a certain range.

[0046] In this way, by adding hydrochloric acid in the chlorine leaching step S2 to adjust the hydrochloric acid concentration of the chlorine leaching solution, the pH of the chlorine leaching solution can be kept almost constant, the distribution behavior of iron and arsenic can be stabilized, and the fluctuation of the distribution behavior that occurred due to the conventional unpredictable process can be suppressed. This means that the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration by the arsenic concentration in the cementation final solution obtained through the cementation step S1, in other words, the cementation final solution (iron-containing arsenic-containing nickel chloride aqueous solution) to be subjected to the iron removal step S3, can be stably adjusted to a predetermined range by suppressing the variation. As a result, iron ions and arsenic ions can be efficiently and effectively removed from the cementation final solution through oxidation and neutralization in the iron removal step S3.

[0047] The addition of hydrochloric acid may be performed to the aqueous solution (including the slurry) at any stage of the chlorine leaching treatment in the chlorine leaching step S2. For example, hydrochloric acid may be added to the cementation residue slurry to be subjected to the chlorine leaching step S2, or to the chlorine leaching slurry (slurry before solid-liquid separation) generated by chlorine leaching.

[0048] The chlorine leaching process in the chlorine leaching step S2 can be carried out using a chlorine leaching device equipped with a plurality of reaction tanks (a total of n reaction tanks) connected in series. In this case, the hydrochloric acid concentration of the chlorine leaching solution can be adjusted by adding hydrochloric acid to the chlorine leaching slurry contained in the final (nth) reaction tank of the plurality of reaction tanks connected in series. As the chlorine leaching reaction proceeds, the pH of the chlorine leaching solution decreases, but the final pH of the chlorine leaching solution can be accurately adjusted by adjusting the hydrochloric acid concentration by adding hydrochloric acid to the chlorine leaching slurry contained in the final reaction tank of the plurality of reaction tanks.

[0049] <3. Iron removal process> As described above, the cementation end liquid obtained through the cementation step S1 is sent to the iron removal step S3. The cementation end liquid is an iron-containing crude nickel chloride aqueous solution from which copper ions have been removed in the cementation step S1, but is an aqueous nickel chloride solution containing iron ions and arsenic ions as impurities (iron-containing arsenic nickel chloride aqueous solution).

[0050] Specifically, in the iron removal step S3, the cementation end liquid is oxidized and neutralized, so that the iron in the cementation end liquid is precipitated as a neutralized precipitate, and the iron-removed end liquid and the iron-removed precipitate are obtained by solid-liquid separation. The oxidation neutralization method utilizes the property that heavy metals such as iron, when they become highly oxidized ions, tend to become hydroxides in the low pH range.

[0051] In the iron removal step S3, the impurity iron is removed by the reaction of the following formula [5]. 2Fe 2+ +Cl2+3NiCO3+3H2O→ 2Fe(OH)3+3Ni 2+ +2Cl - +3CO2···[5]

[0052] As shown in equation [5], in the iron removal step S3, hydroxide precipitates of impurity elements such as iron to be removed are formed from the iron-containing arsenic nickel chloride aqueous solution, which is the cementation end liquid, to obtain a nickel chloride aqueous solution from which impurities have been removed (iron-removed end liquid).

[0053] In general, the chemicals used in the oxidation neutralization method include hypochlorous acid, oxygen, air, and the like as the oxidizing agent in addition to chlorine gas. Also, hydroxides such as caustic soda, ammonia, and the like as the neutralizing agent in addition to nickel carbonate. These chemicals are used in combinations suited to the process conditions, but in a wet smelting process using a nickel sulfide raw material, it is preferable to use chlorine gas as the oxidizing agent and nickel carbonate as the neutralizing agent. For example, chlorine gas is a strong oxidizing agent that is generated in the process and is easy to use. Also, the reason for using nickel carbonate as the neutralizing agent is that it can control the ion concentrations of nickel, sodium, sulfuric acid, and the like throughout the process, and has excellent reactivity during oxidation neutralization.

[0054] Here, the cementation end solution is an aqueous solution of iron-containing arsenic-nickel chloride that contains arsenic as well as iron as impurities. It is known that arsenic ions precipitate by coprecipitation with iron ions, and therefore the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the cementation end solution subjected to the oxidation neutralization reaction by the arsenic concentration is an extremely important reaction index. For example, although a larger iron-arsenic ratio (iron / arsenic) in the cementation end solution is advantageous for removing iron and arsenic, if the value range fluctuates, the oxidation neutralization reaction becomes unstable, and iron and arsenic may not be removed efficiently.

[0055] At this time, in the method for treating nickel sulfide raw material according to the present embodiment, hydrochloric acid is added in the chlorine leaching step S2 to adjust the hydrochloric acid concentration of the chlorine leaching solution produced. This adjusts the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration by the arsenic concentration in the cementation end solution (iron-arsenic-containing nickel chloride aqueous solution) obtained through the cementation step S1.

[0056] As described above, in the chlorine leaching step S2, by adjusting the hydrochloric acid concentration of the chlorine leaching solution by adding hydrochloric acid, the pH of the chlorine leaching solution can be kept almost constant, and the distribution behavior of iron and arsenic can be stabilized to a value almost identical to that in the nickel sulfide raw material. This means that the iron-arsenic ratio (iron / arsenic), obtained by dividing the iron concentration by the arsenic concentration in the cementation end solution obtained through the cementation step S1, in other words, the cementation end solution to be subjected to the iron removal step S3, can be stably adjusted to a predetermined range with reduced variation.

[0057] Therefore, the cementation final liquid to be subjected to the iron removal step S3 has an iron / arsenic ratio (iron / arsenic) stably adjusted to a predetermined range. As a result, iron ions and arsenic ions can be efficiently and effectively removed from the cementation final liquid through oxidation and neutralization in the iron removal step S3. For example, the iron ions in the iron removal final liquid can be efficiently reduced to a low concentration of 0.01 g / L or less, and the arsenic ions can be efficiently reduced to a low concentration of 0.001 g / L or less.

[0058] Specifically, when increasing the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration by the arsenic concentration in the cementation end solution, the hydrochloric acid concentration of the chlorine leaching solution is adjusted to decrease in the chlorine leaching step S2. On the other hand, when decreasing the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration by the arsenic concentration in the cementation end solution, the hydrochloric acid concentration of the chlorine leaching solution is adjusted to increase in the chlorine leaching step S2.

[0059] Preferably, in the chlorine leaching step S2, the hydrochloric acid concentration is adjusted so that the pH of the chlorine leaching solution produced is −0.1 to 0.1. This makes it possible to more stably adjust the iron / arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the cementation final solution by the arsenic concentration. Iron ions and arsenic ions can be more efficiently removed from the cementation final solution.

[0060] <4. Other processes> The iron-removal end liquid obtained by removing impurities such as iron in the iron-removal step S3 is then sent to a cobalt solvent extraction step S4. In the cobalt solvent extraction step S4, nickel and cobalt are separated from the iron-removal end liquid by solvent extraction to obtain a crude nickel chloride solution (NiCl2) and a crude cobalt chloride solution (CoCl2).

[0061] The obtained crude nickel chloride solution and crude cobalt chloride solution are respectively sent to a solution purification step S5, where impurity elements are removed to obtain a high-purity nickel chloride solution and a high-purity cobalt chloride solution. The solution purification step S5 can be configured by combining various impurity removal processes depending on the impurity composition of the solution. For example, a deleading process using an oxidation neutralization method under different conditions from the process in the above-mentioned iron removal step, a dezincing process using an ion exchange method, etc. can be combined.

[0062] The high-purity nickel chloride solution and cobalt chloride solution thus obtained are sent to the electrolysis step S6 (nickel electrolysis step, cobalt electrolysis step). In the electrolysis step S6, electrolytic nickel is produced from the nickel chloride solution by electrolytic winning, and electrolytic cobalt is produced from the cobalt chloride solution by electrolytic winning. EXAMPLES

[0063] 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 in any way.

[0064] Examples and Comparative Examples In the MCLE process using nickel sulfide as a raw material, the iron and arsenic content in the chlorine leaching residue, raw material composition, and cementation end solution was investigated and compared depending on whether or not hydrochloric acid was added in the chlorine leaching process.

[0065] [Comparative Example 1] In Comparative Example 1, in the chlorine leaching step, hydrochloric acid was not added to the chlorine leaching slurry in the final stage reaction tank of multiple reaction tanks connected in series, and the pH of the chlorine leaching solution in that reaction tank was left undisturbed.

[0066] As a result, the average pH value of the chlorine leaching solution was 0.3, and the pH varied within the range of 0.1 to 0.5 during the investigation period. In addition, the iron-arsenic ratio (iron / arsenic), calculated by dividing the iron concentration in the obtained chlorine leaching residue by the arsenic concentration, was 0.6, indicating that most of the arsenic in the nickel sulfide raw material was distributed to the chlorine leaching residue.

[0067] In addition, the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the raw material composition by the arsenic concentration was 35.7, whereas the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the cementation end liquid (iron-containing nickel chloride aqueous solution) obtained through the cementation process by the arsenic concentration was 97.1, which shows a large deviation (see deviation evaluation (f) in Table 1 below). Although a large iron-arsenic ratio (iron / arsenic) in the cementation end liquid is advantageous for iron removal in the iron removal process, the value varied in the range of 46.0 to 156.0, and it was considered that the reaction (oxidation neutralization reaction) in the iron removal process was unstable and iron and arsenic could not be removed efficiently.

[0068] [Example 1] In Example 1, in the chlorine leaching process, hydrochloric acid was added to the chlorine leaching slurry in the final stage reaction tank of multiple reaction tanks connected in series, and the pH of the chlorine leaching solution was adjusted to be maintained at around 0.1.

[0069] As a result, there was almost no variation in the pH of the chlorine leaching solution. Also, the iron / arsenic ratio (iron / arsenic), calculated by dividing the iron concentration in the chlorine leaching residue by the arsenic concentration, was 1.0, and the distribution amounts of iron and arsenic were almost the same.

[0070] In addition, the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the raw material composition by the arsenic concentration was 34.9, whereas the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the cementation end liquid (iron-containing nickel chloride aqueous solution) obtained through the cementation process by the arsenic concentration was 42.9, and no large deviation (see deviation evaluation (f) in Table 1 below) was confirmed. The iron-arsenic ratio (iron / arsenic) in the cementation end liquid had almost no variation, and it was presumed that the reaction (oxidation neutralization reaction) in the iron removal process proceeded stably, allowing efficient removal of iron and arsenic.

[0071] [Example 2] In Example 2, in the chlorine leaching process, hydrochloric acid was added to the chlorine leaching slurry in the final stage reaction tank of multiple reaction tanks connected in series, and the hydrochloric acid concentration in the chlorine leaching solution was adjusted to be higher than that in Example 1, so that the pH of the chlorine leaching solution was maintained at around -0.1.

[0072] As a result, there was almost no variation in the pH of the chlorine leaching solution in Example 2. In addition, the iron / arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the chlorine leaching residue by the arsenic concentration was 1.4.

[0073] In addition, the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the raw material composition by the arsenic concentration was 61.1, whereas the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration in the cementation end liquid (iron-containing nickel chloride aqueous solution) obtained through the cementation process by the arsenic concentration was 73.1, which was a smaller deviation than in Example 1 (see deviation evaluation (f) in Table 1 below). The iron-arsenic ratio (iron / arsenic) in the cementation end liquid had almost no variation, and it was presumed that the reaction (oxidation neutralization reaction) in the iron removal process proceeded stably, allowing efficient removal of iron and arsenic.

[0074] The results of Comparative Example 1, Examples 1 and 2 are summarized in Table 1 below.

[0075] [Table 1]

[0076] From the above results, it was found that by adding hydrochloric acid in the chlorine leaching process and adjusting the hydrochloric acid concentration of the chlorine leaching solution produced, it is possible to suppress fluctuations in the distribution of iron and arsenic to the chlorine leaching solution and chlorine leaching residue, and as a result, it is possible to stabilize the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration by the arsenic concentration in the cementation end solution (iron-containing nickel chloride aqueous solution) obtained through the cementation process.

Claims

1. A method for treating a nickel sulfide raw material containing iron and arsenic as impurities, comprising the steps of: a cementation step of mixing a copper-containing, ferrous, crude nickel chloride aqueous solution containing divalent copper ions with a nickel sulfide raw material, and displacing and leaching nickel in the nickel sulfide raw material with the copper ions in the copper-containing, ferrous, crude nickel chloride aqueous solution to generate a cementation slurry which is a mixture of the ferrous crude nickel chloride aqueous solution from which the copper ions have been removed and a precipitate containing copper sulfide, and separating the resulting cementation slurry into a cementation final liquid and a cementation residue by solid-liquid separation; a chlorine leaching step of repulping the cementation residue to prepare a cementation residue slurry, injecting chlorine gas into the cementation residue slurry to leach heavy metals in the cementation residue to produce a chlorine leached slurry, and separating the slurry into a chlorine leached solution and a chlorine leached residue by solid-liquid separation; The chlorine leachate is repeatedly used as the copper-containing, iron-containing crude nickel chloride aqueous solution, In the chlorine leaching step, hydrochloric acid is added to adjust the hydrochloric acid concentration of the chlorine leaching solution to be produced, thereby adjusting the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration of the cementation final solution by the arsenic concentration. Method for processing nickel sulfide raw materials.

2. In the chlorine leaching step, the hydrochloric acid concentration is adjusted so that the pH of the chlorine leaching solution is −0.1 to 0.

1.

2. The method for treating nickel sulfide raw material according to claim 1.

3. A method for removing iron from an aqueous solution of iron-containing crude nickel chloride containing iron and arsenic as impurities, comprising the steps of: In addition to the raw material treatment process according to claim 1, The method further includes a deironization step of oxidizing and neutralizing the cementation end liquid to cause iron in the cementation end liquid to precipitate as a neutralized precipitate, and separating the resulting deironized end liquid and the deironized precipitate by solid-liquid separation, In the chlorine leaching step, hydrochloric acid is added to adjust the hydrochloric acid concentration of the chlorine leaching solution to be produced, thereby adjusting the iron-arsenic ratio (iron / arsenic) obtained by dividing the iron concentration of the cementation final solution by the arsenic concentration. A method for removing iron from an aqueous solution of crude nickel chloride containing iron.

4. In the chlorine leaching step, When increasing the iron / arsenic ratio (iron / arsenic), the hydrochloric acid concentration of the chlorine leachate is decreased; When the iron / arsenic ratio (iron / arsenic) is to be decreased, the hydrochloric acid concentration of the chlorine leaching solution is increased. The method for removing iron from an aqueous solution of iron-containing crude nickel chloride according to claim 3.

5. In the chlorine leaching step, the hydrochloric acid concentration is adjusted so that the pH of the chlorine leaching solution is −0.1 to 0.

1.

5. The method for removing iron from an aqueous solution of iron-containing crude nickel chloride according to claim 3.

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