JP6350684B2 - Method for hydrometallizing nickel oxide ore - Google Patents

Description

  The present invention relates to a hydrometallurgical method using high-pressure acid leaching of nickel oxide ore, and more particularly to a hydrometallurgical method capable of increasing the nickel recovery rate.

  As one of the hydrometallurgical methods for nickel oxide ore, a high pressure acid leach (HPAL) process using sulfuric acid is known. Unlike the conventional dry smelting process, which is a conventional nickel oxide ore smelting process, this process does not involve reduction or drying of the oxide ore at high temperatures, and is consistently processed in a wet process, so it is energetic. And cost advantageous. In addition, it is possible to obtain a sulfide containing nickel and cobalt concentrated to a nickel quality of about 50 to 60% by mass (hereinafter also referred to as nickel cobalt mixed sulfide), and has a feature of easily purifying high-purity nickel. is there.

When nickel oxide ore as a raw material is subjected to high-pressure acid leaching and nickel is recovered as a product, the treatment is generally performed in accordance with the following steps (a) to (d).
(A) After adding water to the crushed nickel oxide ore to make a slurry, sulfuric acid is added to the slurry, and then charged into a reaction vessel such as an autoclave, and kept at a temperature of about 240 to 280 ° C. under high pressure. Thus, valuable materials such as nickel and cobalt contained in the nickel oxide ore are leached, and after leaching, the slurry is taken out from the reaction vessel and separated into a leaching solution containing nickel and cobalt and a leaching residue by a settling tank. Liquid separation process.
(B) An impurity such as iron is precipitated in a state where a neutralizing agent is added to the leachate and adjusted to a predetermined pH, and a coagulant is added to the neutralized slurry containing neutralized starch of the obtained impurity. A neutralization step of obtaining a post-neutralization solution (also referred to as a neutralization end solution) containing nickel and cobalt by solid-liquid separation of the neutralized starch;
(C) In order to remove only zinc and copper as sulfides without sulphurizing valuable nickel and cobalt contained in the solution after neutralization, the addition amount of a sulfurizing agent in the solution after neutralization is within an appropriate range. A dezincification step in which the added sulfurized starch (also referred to as zinc starch) is solid-liquid separated to obtain a post-dezincification solution (also referred to as dezincification final solution) by adding while controlling.
(D) A nickel recovery step of separating and recovering the mixed sulfide after adding a sulfiding agent to the post-dezinced solution to form a nickel cobalt mixed sulfide.

  For example, Patent Document 1 discloses a wet smelting method using the above-described high-pressure acid leaching method, and this wet smelting method was obtained by a leaching step of leaching nickel oxide ore with sulfuric acid and then solid-liquid separation. Neutralization step of adding neutralizing agent to leachate to produce neutralized starch containing impurities, removing this to obtain a neutralized solution, and adding hydrogen sulfide gas to the neutralized solution to add zinc It consists of a dezincification step in which sulfides are generated and removed to obtain a nickel recovery mother liquor, and a nickel recovery step in which hydrogen sulfide gas is added to the mother liquor to recover nickel and cobalt as mixed sulfides.

  In the method of Patent Document 1, a leaching residue is appropriately added to the leachate in the neutralization step, the pH of the neutralization final solution is adjusted to 3.0 to 3.5, and the neutralization final solution is further removed in the dezincing step. A sulfidation reaction was carried out in a state in which a suspension consisting of neutralized starch and leach residue remained in the neutralized final solution so that the turbidity of the mixture became 100 to 400 NTU (Nephelometric Turbidity Unit). The slurry containing the sulfide starch is subjected to solid-liquid separation in the filtration step in the dezincification step to obtain the sulfide starch and a final solution containing nickel and cobalt.

JP 2010-37626 A

  In the HPAL process using nickel oxide ore as a raw material as described above, the conditions for producing a nickel sulfide starch and the conditions for producing a zinc sulfide starch in the dezincification step are close to each other. In some cases, nickel co-precipitated into the material, resulting in loss. Since the recovery rate of nickel greatly affects the economics of the process, it is desired to reduce the nickel loss as much as possible.

  The present invention has been made in view of such a situation. In the hydrometallurgical method using high pressure acid leaching of nickel oxide ore, when removing zinc contained in the nickel oxide ore, it is necessary to coexist with impurities such as zinc and copper. An object of the present invention is to provide a hydrometallurgical method capable of increasing the nickel recovery rate by reducing the amount of nickel to be precipitated.

  In order to achieve the above object, the present inventors added a sulfidizing agent to the post-neutralization solution after neutralization of the leachate obtained by high-pressure acid leaching of nickel oxide ore, and dezincation reaction (sulfurization reaction) by sulfurization. 2), two or more reaction tanks for the dezincification reaction are provided, they are connected in series, and the distribution ratio of hydrogen sulfide gas blown into the reaction tanks is adjusted to increase the nickel recovery rate. The present inventors have found that this can be done and have completed the present invention.

  That is, the method for hydrometallizing nickel oxide ore according to the present invention includes a leaching step in which leaching residue is removed after acid leaching of nickel oxide ore under high pressure to obtain a leachate, and a neutralizing agent is added to the leachate. Neutralization step of removing the neutralized starch to obtain a post-neutralization solution, and a dezincification step of removing the zinc starch produced by blowing hydrogen sulfide gas into the post-neutralization solution to obtain a post-dezincification solution And a nickel recovery process for recovering nickel as a sulfide by adding a sulfiding agent to the solution after dezincing, and the hydrogen sulfide gas in the dezincing step The second and subsequent steps from the top of the total amount of hydrogen sulfide gas blown into all the reaction tanks while the post-neutralized solution was sequentially flowed into two or more reaction tanks connected in series. 50% or more of hydrogen sulfide gas was blown into the reaction tank 9 % Are characterized by adjusting below.

  According to the present invention, when removing zinc contained in nickel oxide ore, the amount of nickel co-precipitated with impurities such as zinc and copper can be reduced to increase the nickel recovery rate.

It is a process flowchart which shows the hydrometallurgy method of the nickel oxide ore of one specific example of this invention. It is the graph which plotted the relationship between the particle diameter of the zinc sulfide of each sample obtained in the Example, and the blowing ratio of the hydrogen sulfide gas at the time of the production | generation. It is the graph which plotted the relationship between the Ni quality of the zinc sulfide of each sample obtained in the Example, and the blowing ratio of hydrogen sulfide gas at the time of the production. It is the graph which plotted the relationship between the Ni quality of the zinc sulfide of each sample obtained in the Example, and a particle size.

  Hereinafter, the hydrometallurgical method of nickel oxide ore of one specific example of the present invention will be described. As shown in FIG. 1, in this smelting method, first, in the leaching step S1, the raw material nickel oxide ore is finely granulated by a crushing means such as a crusher, and then water is added to form a slurry. After the addition, it is charged into a pressure vessel such as an autoclave and subjected to sulfuric acid leaching treatment at a high temperature and high pressure of, for example, 240 to 280 ° C. to leach valuable nickel and cobalt.

  Next, in the solid-liquid separation step S2, the slurry obtained by the sulfuric acid leaching is washed in multiple stages, and then the leaching residue is removed from the slurry by solid-liquid separation to obtain a leachate containing nickel, cobalt, and impurity elements. Next, in the neutralization step S3, an alkali such as slaked lime or calcium carbonate is added to the leachate as a neutralizing agent, and the pH of the leachate is adjusted to precipitate the impurity elements as neutralized starch. A flocculant (coagulant) is added to the slurry containing the neutralized starch, followed by solid-liquid separation to remove the neutralized starch, thereby obtaining a neutralized final solution containing nickel and cobalt. In addition, you may repeat the neutralization starch obtained by neutralization process S3 to solid-liquid separation process S2 as needed. Moreover, as shown by the dotted line in FIG. 1, at least a part of the leaching residue obtained in the solid-liquid separation step S2 may be added to the leaching solution in the neutralization step S3.

  Next, in the zinc removal step S4, hydrogen sulfide gas as a sulfiding agent is blown into the neutralized final solution to produce a sulfide containing zinc (zinc sulfide), and the slurry containing the sulfide is solidified. By separating the liquid, zinc sulfide is removed to obtain a liquid after dezincing. Finally, in nickel recovery step S5, a nickel-cobalt mixed sulfide containing nickel and cobalt is generated by adding a sulfiding agent such as hydrogen sulfide gas to the solution after dezincing, and a slurry containing the nickel-cobalt mixed sulfide is produced. The nickel-cobalt mixed sulfide is recovered by solid-liquid separation and a post-sulfurized liquid (poor liquid) is obtained. This poor solution may be repeated in the solid-liquid separation step S2 as shown in FIG. 1 as necessary.

  In one specific example of the hydrometallurgical method of the present invention, zinc is selectively precipitated and precipitated as a sulfide in the dezincing step S4 to separate it from nickel and cobalt. At that time, two or more reaction tanks for performing a sulfurization reaction by blowing hydrogen sulfide gas into the neutralized final liquid are provided, and the neutralized final liquid obtained in the neutralization process flows in order by connecting the plurality of reaction tanks in series. Like that. Furthermore, with respect to the amount of hydrogen sulfide gas blown into all these reaction tanks, the ratio of the amount of hydrogen sulfide gas blown into the reaction tanks after the first tank in the series of reaction tanks connected in series (hereinafter referred to as “blowing”). (Also referred to as “compression ratio”) to an appropriate range. Thereby, the amount of nickel co-precipitated with impurities such as zinc and copper can be reduced, and the nickel recovery rate can be increased.

  Specifically, in the dezincing step S4, the No. 1 reaction tank, No. 2 reaction tank, No. 3 reaction tank, etc. from the top in the order in which the neutralization final solution flows through the reaction tank in which the dezincification reaction is performed. When the reactor is composed of n reactors in the No. n reactor, the No. 2 reactor and the subsequent reactors with respect to the total amount of hydrogen sulfide gas injected into all reactors from the No. 1 reactor to the No. n reactor. The amount of hydrogen sulfide gas blown into (n-1) reactors (i.e., the blow-in ratio) is adjusted within the range of 50% to 90%. Thereby, the amount of nickel co-precipitated with impurities such as zinc and copper can be reduced.

  Furthermore, by setting the blowing ratio higher as described above, the particle size of the sulfide starch can be increased. As a result, it becomes possible to improve the solid-liquid separation in the dezincing step. That is, in the dezincing process, sulfide starch consisting of fine particles is likely to be generated, and if the slurry containing this is solid-liquid separated with a filtration device such as a filter press, the filter cloth will be clogged immediately and the flow rate will decrease. Therefore, frequent backwashing and replacement work of the filter cloth is necessary for the recovery, and the production efficiency may be lowered. On the other hand, since the particle size of a sulfide starch becomes large by setting a blowing ratio high as above-mentioned, filterability improves.

  As described above, when improving the solid-liquid separation in addition to the improvement of the nickel recovery rate, it is preferable to adjust the blowing ratio within the range of 60 to 90%, and within the range of 60 to 85%. More preferably. This makes it possible to increase the particle size of the zinc sulfide (also referred to as “dezinced starch”) that is finally produced, and to prevent clogging of the filter cloth in a filtration device such as a subsequent filter press. Can do. As a result, the liquid passing capacity of the filtration device is improved, so that productivity can be increased. The reason why the particle size of the dezincified starch grows large by increasing the blowing ratio in this way is that when the blowing ratio is increased, in the No. 1 reaction tank, the impurities including zinc generated at the early stage of the sulfurization reaction This is because the number of fine particles made of sulfide decreases, and as a result, sulfide grows with these few fine particles as nuclei (also referred to as “seed”) in the No. 2 reaction tank and later.

  When the above blowing ratio is less than 60%, the proportion of hydrogen sulfide gas blown into the No. 1 reaction tank is relatively high, and as a result, fine zinc sulfide particles that serve as nuclei in the No. 1 reaction tank Is excessively generated, and after the No. 2 reactor, the sulfide grows with these many fine particles as nuclei, so it is difficult to obtain a zinc sulfide having a large particle size. On the other hand, when the blowing ratio exceeds 90%, the production of fine zinc sulfide as a nucleus in the No. 1 reaction tank is suppressed, so the number of seeds is insufficient. Growth may be insufficient. That is, seeds can be stably generated by blowing more than 10% and less than 40% of the hydrogen sulfide gas supplied to the entire reaction tank into the No. 1 reaction tank. The specific blowing ratio may be appropriately adjusted so that the particles grow to such an extent that the filter cloth is not easily clogged during the subsequent filtration process.

  When three or more reaction vessels are provided in series, the reaction vessel located at the end may serve as a buffer vessel without blowing much hydrogen sulfide gas. By making the reaction tank located at the end in this way a buffer tank, the reaction time can be ensured in the buffer tank even if a short path of the processing liquid occurs in the reaction tank located upstream of the reaction tank. , A decrease in the overall reaction efficiency can be suppressed. However, if there are many reaction tanks in which the sulfidation reaction is not substantially carried out, the waste of equipment costs and energy costs increases, and the slurry retained in these excess reaction tanks is oxidized by the entrained air and dezinced. The number of reaction tanks for performing the dezincification reaction is preferably 3 tanks or less because problems such as re-dissolution of starch may occur. Further, separately prepared zinc sulfide or zinc sulfide recovered by solid-liquid separation may be supplied as seed to the No. 1 reaction tank, whereby a coarser zinc sulfide can be generated.

  In the dezincing step S4 described above, it is preferable to carry out the dezincing reaction in the range of pH 2.5 to 3.5. When this pH is less than 2.5, zinc once converted to sulfide may be redissolved and separation of zinc may be insufficient. Conversely, when the pH exceeds 3.5, elements that are not subject to removal, such as iron and nickel, may precipitate, increasing the starch load on the filter cloth and filter during the subsequent filtration process, In the case of iron or the like, a lot of fine starch is generated, so that the filter cloth is clogged. Therefore, it is necessary to backwash the filter cloth frequently in order to ensure a sufficient flow rate, and the production efficiency decreases. There is a fear.

In the above dezincification reaction, an acid is generated after the reaction as shown in the following formula 1, so that the pH is maintained in the range of 2.7 to 3.0 from the viewpoint of giving a margin to the above range. More preferably.
[Formula 1]
ZnSO ₄ + H ₂ S → ZnS + H ₂ SO ₄

  The nickel oxide ore was hydrometallized by high-temperature and high-pressure leaching along the process flow shown in FIG. 1, and nickel was recovered in the form of sulfide. Specifically, nickel oxide ore consisting of laterite ore, saprolite ore and limonite ore is put together with sulfuric acid into an autoclave as a pressure vessel, and heated to a temperature of 240 to 260 ° C with a steam heater to perform high pressure press leaching. Thereafter, the leaching residue was solid-liquid separated from the obtained leaching slurry to obtain a leaching solution. After adding slaked lime as a neutralizing agent to this leachate and adjusting the pH to a range of 3.0 to 3.5, a neutralized starch is produced, and then an anionic flocculant is added to the neutralized starch. The product was removed by solid-liquid separation to obtain a neutralized final solution.

Next, three reaction tanks (No. 1 reaction tank, No. 2 reaction tank, and No. 2) each having a substantially cylindrical shape each having a diameter of 7.7 m × height of 12 m (capacity: 460 m ³ ) and connected in series. 3 reaction tanks), and the above neutralized solution is continuously supplied to the top No. 1 reaction tank at a flow rate of 1200 to 1450 m ³ / hr, and the No. 1 reaction tank, No. 2 reaction tank, and It flowed in order of No. 3 reaction tank. Further, hydrogen sulfide gas was blown into each of these three reaction tanks to sulfidize zinc contained in the neutralized final solution to produce zinc sulfide. At that time, the ratio of the amount of hydrogen sulfide gas blown into the No. 2 reaction vessel and No. 3 reaction vessel, that is, the blowing ratio, with respect to the amount of hydrogen sulfide gas blown into all three reaction vessels. It was gradually changed within the range from 5.1% to 86.3%.

  Then, the sulfidized liquid extracted from the No. 3 reaction tank at the end was supplied to a Buchner funnel having a filter cloth on a 60 cm diameter filter panel provided with a large number of filtration holes, and the filtrate side was evacuated. Solid-liquid separation was performed by suction. Thus, the zinc sulfide (dezinced starch) of samples 1-46 produced | generated on the conditions from which blowing ratios differ was obtained. Note that most of the hydrogen sulfide gas was blown into the No. 2 reaction tank and No. 3 reaction tank, and the zinc sulfide grown in the No. 2 reaction tank was in a dissolved state. The No. 3 reaction tank was used as a place for finishing the growth by reacting with the residual hydrogen sulfide gas. Specifically, the amount of injection into the No. 3 reaction tank was adjusted appropriately as long as the injection ratio was not changed in accordance with the growth state of the sampled zinc sulfide particle diameter.

  Table 1 below shows the blowing ratio at the time of producing the zinc sulfide of the samples 1 to 46 and the particle diameter of the zinc sulfide produced under these conditions. Moreover, the graph which plotted the relationship between these blowing ratio and the particle size of zinc sulfide is shown in FIG. The particle size of zinc sulfide was measured using a microtrack while observing a sample collected during steady operation with a microscope. In addition, when producing the zinc sulfide of these samples 1 to 46, the pH of the slurry in the reaction vessel was maintained in the range of 2.7 to 2.9, and the liquid temperature was in the range of 60 to 67 ° C. The composition of this neutralized final solution was within the range of nickel concentration 3.5 to 4.0 g / L, iron concentration 0.7 to 1.4 g / L, and zinc concentration 60 to 140 mg / L. It was. And the zinc concentration of the solution after dezincification was reduced to about 5 to 12 mg / L.

  As can be seen from the results of Table 1 and FIG. 2, the zinc sulfide samples 24 to 46 in which the hydrogen sulfide gas blowing ratio after the No. 2 reaction tank was adjusted to 60% to 90% A coarse zinc sulfide of approximately 10 μm or more was obtained. In the preparation of zinc sulfide of these samples 24 to 46, smelting was continued for several days over at least 24 hours under the conditions of the respective blowing ratios, but the slurry extracted from the No. 3 reactor was supplied. No clogging occurred in the filter. On the other hand, in Samples 1 to 23 in which the blowing ratio was adjusted to less than 60%, the zinc sulfide particle sizes were all less than 10 μm and fine. In the preparation of the zinc sulfides of these samples 1 to 23, when smelting was continued continuously under the conditions of each blowing ratio, the filter was clogged before 24 hours passed.

  Next, among the zinc sulfides of the above samples 1 to 46, the nickel quality of each of 37 types of arbitrarily selected zinc sulfide samples was measured by ICP. Table 2 below shows the nickel quality in the obtained zinc sulfide together with the blowing ratio. Moreover, the graph which plotted the relationship between these nickel grades and blowing ratios is shown in FIG. Furthermore, the graph which plotted the relationship between the particle size of zinc sulfide and nickel quality is shown in FIG.

From Table 2 and FIG. 3, it can be seen that the nickel quality in the zinc sulfide can be reduced to 1% or less by setting the blowing ratio to 50% or more. Also, from FIG. 4, in order to make the nickel quality 1% or less, the particle size of zinc sulfide should be approximately 10 μm or more, and this indicates that the blowing ratio of hydrogen sulfide gas is approximately from Table 1 and FIG. It can be seen that it should be 60% or more. Thus, when making the particle size of zinc sulfide 10 μm or more, in addition to the effect of improving the nickel recovery rate, the effect of improving the filterability is also obtained.

Claims (2)

A leaching process in which leaching residue is removed after acid leaching of nickel oxide ore under high pressure to obtain a leachate, and a neutralized starch produced by adding a neutralizing agent to the leachate is removed to obtain a post-neutralization solution A neutralization step, a zinc removal step in which zinc starch formed by blowing hydrogen sulfide gas into the solution after neutralization is removed to obtain a solution after dezincification, and a sulfurizing agent is added to the solution after dezincification to form nickel A nickel oxide ore hydrometallurgy method comprising a nickel recovery step for recovering as a sulfide,
The blowing of the hydrogen sulfide gas in the dezincing step is performed by sequentially flowing the post-neutralized liquid into two or more reaction vessels connected in series, and the total amount of hydrogen sulfide gas blown into all the reaction vessels. In contrast, the method for hydrometallurgy of nickel oxide ore is characterized in that the amount of hydrogen sulfide gas blown into the second and subsequent reactors is adjusted to 50% or more and 90% or less. Wherein in the dezincification process, and it performs the sulfurization reaction in the range of pH2.5 to 3.5, hydrometallurgical method for nickel oxide ore according to claim 1.

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