WO2019093053A1 - Leaching treatment method and hydrometallurgical method for nickel oxide ore - Google Patents

Leaching treatment method and hydrometallurgical method for nickel oxide ore Download PDF

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WO2019093053A1
WO2019093053A1 PCT/JP2018/037731 JP2018037731W WO2019093053A1 WO 2019093053 A1 WO2019093053 A1 WO 2019093053A1 JP 2018037731 W JP2018037731 W JP 2018037731W WO 2019093053 A1 WO2019093053 A1 WO 2019093053A1
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leaching
sulfuric acid
slurry
concentration
nickel
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PCT/JP2018/037731
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French (fr)
Japanese (ja)
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啓明 永井
二郎 早田
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住友金属鉱山株式会社
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Priority to PH12020500468A priority Critical patent/PH12020500468A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B23/00—Obtaining nickel or cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
    • C22B3/08—Sulfuric acid, other sulfurated acids or salts thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to a method of leaching treatment to nickel oxide ore, more specifically, a leaching treatment method of leaching nickel by adding sulfuric acid to a slurry of nickel oxide ore, and nickel oxide ore to which the leaching method is applied It relates to a hydrometallurgical process.
  • the low grade nickel oxide ore is roughly classified into two: limonite ore with high iron grade and low alkali grade such as magnesium and silica, and Saprolite ore containing a large amount of alkali ingredient, HPAL Limonite ore is mainly used as a raw material of the method.
  • nickel oxide ore contains magnesium as an impurity in addition to valuable metals such as nickel and cobalt. Therefore, for example, when the magnesium quality is high in the nickel oxide ore, it is necessary to increase the addition amount of sulfuric acid in order to maintain the target nickel leaching rate in the leaching process.
  • the amount of sulfuric acid added is increased, not only the basic unit of sulfuric acid is increased to increase the cost, but also there is a problem that the progress of equipment corrosion used for the leaching treatment is accelerated. Therefore, in actual operation, the unreacted sulfuric acid concentration (free sulfuric acid concentration) contained in the slurry after the leaching reaction is monitored, and the addition amount of sulfuric acid is controlled so that the free sulfuric acid concentration is within the predetermined range. There is.
  • the present invention has been proposed in view of such circumstances, and provides a method capable of effectively reducing the amount of sulfuric acid used while maintaining a high nickel leaching rate, in a method of leaching treatment for nickel oxide ore.
  • the purpose is
  • the present inventors diligently studied to solve the problems described above.
  • the amount of sulfuric acid added depends on the concentration of metal components in the leaching slurry obtained by the leaching treatment, particularly the concentration of magnesium, in the leaching slurry.
  • concentration of free sulfuric acid By adjusting the concentration of free sulfuric acid to a predetermined concentration, it is found that the amount of sulfuric acid used can be effectively reduced while maintaining a high nickel leaching rate, and the present invention has been completed.
  • a leaching treatment is performed by adding sulfuric acid to a slurry of magnesium oxide-containing nickel oxide ore (ore slurry), and a leaching consisting of a leaching solution containing nickel and a leaching residue
  • the addition amount of the sulfuric acid is adjusted so that the concentration of free sulfuric acid in the leached slurry is in the range of 25 g / L to 55 g / L. It is a leaching method.
  • the third invention of the present invention is the leaching treatment method according to the first or second invention, wherein the magnesium concentration in the leaching slurry is measured by ICP emission spectrometry or atomic absorption spectrometry.
  • a fourth invention of the present invention is a method for wet smelting nickel oxide ore in which valuable metal containing nickel is recovered from nickel oxide ore using sulfuric acid, wherein the slurry of nickel oxide ore (ore slurry) Are subjected to a leaching treatment by adding sulfuric acid thereto to obtain a leaching slurry consisting of a leaching solution containing nickel and a leaching residue, and in the leaching step, the addition amount of the sulfuric acid is obtained by the leaching treatment. And adjusting the concentration of free sulfuric acid in the leached slurry to a predetermined concentration in accordance with the concentration of magnesium in the leached slurry.
  • the present embodiment when expressing as “X to Y” (X and Y are arbitrary numerical values), it means “more than X and less than Y” unless otherwise specified.
  • Leaching method for nickel oxide ore is performed by adding sulfuric acid to a slurry of nickel oxide ore containing magnesium (ore slurry), and a leaching slurry comprising a leachate containing nickel and a leaching residue How to get This leaching method is carried out in a high temperature and pressure environment using, for example, a high temperature pressure vessel (autoclave).
  • a high temperature pressure vessel autoclave
  • the amount of sulfuric acid added to the ore slurry is such that the concentration of free sulfuric acid in the leaching slurry becomes a predetermined concentration according to the magnesium concentration in the leaching slurry obtained by the leaching treatment To adjust.
  • the nickel oxide ore to be subjected to the leaching treatment is mainly so-called laterite ore such as limonite or saprolite ore.
  • the nickel content (content ratio) of laterite ore is usually about 1.0% by mass to about 2.0% by mass, and is contained as a hydroxide or a silica earth (magnesium silicate) mineral.
  • the iron content is about 10% by mass to 50% by mass, and is mainly in the form of trivalent hydroxide (gesite), but a part of divalent iron is contained in siliceous earth mineral Ru.
  • oxide ores containing valuable metals such as nickel, cobalt, manganese, copper and the like, such as manganese lumps and the like stored in the deep sea floor are used.
  • nickel oxide ore is classified at a predetermined classification point to remove oversized ore particles, then water is added to the undersized ore particles to prepare an ore slurry, and the prepared ore slurry is prepared.
  • Sulfuric acid is added to cause a leaching reaction.
  • the concentration of the ore slurry is not particularly limited, but it is preferable to adjust the concentration of the ore in the slurry to about 15% by mass to 45% by mass. If the slurry concentration is less than 15% by mass, large equipment is required to obtain the same residence time during the leaching process. Also, the amount of sulfuric acid added may be relatively increased. On the other hand, when the slurry concentration exceeds 45% by mass, although the scale of the equipment can be reduced, the problem arises that the transport of the high concentration slurry becomes difficult (friction in the pipe frequently, energy is required, etc.).
  • the leaching reaction and high temperature thermal hydrolysis reaction represented by the following formulas (i) to (v) Leaching as sulfate and immobilization of the leached iron sulfate as hematite are performed.
  • the liquid portion of the obtained leaching slurry usually contains divalent and trivalent iron ions in addition to nickel, cobalt and the like.
  • the temperature (leaching reaction temperature) in the leaching treatment is not particularly limited, but is about 220 ° C. to 280 ° C., and preferably about 240 ° C. to 270 ° C. By reacting in such a temperature range, most of iron in the ore can be fixed as hematite. If the reaction temperature is less than 220 ° C., the rate of the high-temperature thermal hydrolysis reaction will be slow, and iron will remain dissolved in the reaction solution, increasing the solution load for removing iron. In addition, as iron is dissolved and remains, the amount of neutralizing agent used to neutralize the dissolved iron in the subsequent treatment increases. On the other hand, if the reaction temperature exceeds 270 ° C, although the high temperature thermal hydrolysis reaction itself is promoted, it becomes difficult to select the material of the reaction container used for high temperature pressure leaching, and the thermal energy cost for temperature rise rises. Do.
  • the amount of addition of sulfuric acid used for the leaching treatment is generally an excess amount, for example, about 300 kg to 400 kg per ton of ore.
  • the magnesium grade in the ore slurry is high, this magnesium consumes a large amount of sulfuric acid to cause the leaching reaction. Therefore, in order to keep the leaching rate of nickel high, it is necessary to increase the addition amount of sulfuric acid used for the leaching treatment.
  • the magnesium grade in the ore slurry is low, it is desirable to keep the leaching rate of nickel high while suppressing the addition amount of sulfuric acid used for the leaching treatment.
  • the amount (addition amount) of sulfuric acid added to the ore slurry in the leaching process is adjusted according to the magnesium concentration in the leached slurry obtained by the leaching process. Specifically, the amount of added sulfuric acid is adjusted so that the concentration of free sulfuric acid in the leached slurry becomes a predetermined concentration, in accordance with the magnesium concentration in the leached slurry obtained by the leaching treatment. For example, according to the magnesium concentration in the leached slurry, the addition amount of sulfuric acid is adjusted so that the free sulfuric acid concentration in the leached slurry is in the range of 25 g / L to 55 g / L.
  • the magnesium concentration in the leached slurry can be measured, for example, by ICP emission spectrometry or atomic absorption spectrometry. According to such a measurement method, the magnesium concentration can be rapidly measured, which is preferable. In addition, since the magnesium concentration can be measured rapidly in this way, even if the magnesium grade in the ore slurry fluctuates, the fluctuation can be detected immediately from the magnesium concentration in the leached slurry, and according to the result, it is promptly It is possible to adjust the concentration of free sulfuric acid to
  • the magnesium grade in the ore slurry to be subjected to leaching treatment is measured, and the amount of added sulfuric acid is adjusted so that the free sulfuric acid concentration in the leached slurry becomes the appropriate range by the magnesium grade in the ore slurry. It is also conceivable to do this.
  • a fluorescent X-ray analysis method is used to measure the magnesium quality of the ore slurry, and in the measurement by the fluorescent X-ray analysis method, including the sample preparation, until the measurement results are obtained It will take a long time of about 8 hours.
  • the magnesium concentration in the leached slurry can be promptly and appropriately determined by the measurement method such as ICP emission analysis or atomic absorption analysis as described above. Since it can be measured, even when the magnesium grade in the ore slurry fluctuates, the amount of added sulfuric acid can be promptly adjusted so that the concentration of free sulfuric acid in the leached slurry is in an appropriate range.
  • the free sulfuric acid concentration in the leached slurry is the concentration of free sulfuric acid at the end of leaching, and is not particularly limited, but is preferably about 25 g / L to 55 g / L, and about 34 g / L to 50 g / L. Is more preferred.
  • the addition amount of sulfuric acid so as to obtain such a free sulfuric acid concentration, it is possible to leach nickel at a high leaching rate from the nickel oxide ore containing magnesium.
  • it is such a free sulfuric acid concentration the leaching residue with high true density can be produced
  • the concentration of free sulfuric acid in the leaching slurry is less than 25 g / L
  • the slurry containing the leaching residue is subjected to a sedimentation operation, the solid content is not sufficiently concentrated or a large amount of SS is present in the supernatant . This is considered to be due to the fact that the reaction rate of high temperature thermal hydrolysis is slow, dehydration of iron hydroxide does not proceed sufficiently, and hematite with low true density is formed.
  • the magnesium concentration in the leached slurry obtained by the leaching treatment is periodically monitored, and the ore to be subjected to the leaching treatment according to the magnesium concentration. Adjust the amount of sulfuric acid added to the slurry. This makes it possible to effectively reduce the amount of sulfuric acid used while maintaining a high nickel leaching rate.
  • the degree of progress of the leaching reaction can be performed by monitoring the grade of nickel in the leached residue discharged, and it is desirable to finely adjust the concentration of free sulfuric acid according to the grade of nickel.
  • wet smelting method of nickel oxide ore is a wet refining method by the high temperature pressure acid leaching method (HPAL method) which leaches under high temperature pressurization.
  • HPAL method high temperature pressure acid leaching method
  • FIG. 2 is a process diagram showing an example of the flow of the hydrometallurgical method of nickel oxide ore.
  • the wet smelting method of nickel oxide ore is the ore slurrying step S1 of crushing or classifying the raw material nickel oxide ore to prepare ore slurry, and adding sulfuric acid to the ore slurry to apply leaching treatment under high temperature pressure and leaching
  • the ore slurrying step S1 is a step of preparing an ore slurry from nickel oxide ore which is a raw material ore, and is a pretreatment step of so-called leaching treatment (leaching step S2). Specifically, in the ore slurrying step S1, after sorting at a predetermined classification point to remove oversized ore particles, water is added to the undersized ore particles to prepare an ore slurry.
  • the classification method of the nickel oxide ore is not particularly limited as long as it can be classified based on the desired particle size, and can be performed by sieving using a grizzly or a vibrating screen. Further, with regard to the classification point, a classification point for obtaining an ore slurry composed of ore particles having a particle diameter value or less desired can be appropriately set.
  • so-called laterite ore such as limonite ore and saprolite ore can be used.
  • the nickel content of laterite ore is usually about 1.0% by weight to 2.0% by weight.
  • magnesium is contained as a impurity at a predetermined ratio.
  • Leaching process S2 is a process of adding sulfuric acid to ore slurry under high temperature pressurization, and leaching valuable metals, such as nickel in ore. Specifically, in the leaching step S2, sulfuric acid is added to the ore slurry using an autoclave, and stirring is performed under the conditions of a temperature of about 220 ° C. to 280 ° C. and a pressure of about 3 MPa to 5 MPa. Generate a slurry.
  • the leaching process in the leaching step S2 is carried out so that the concentration of free sulfuric acid in the leached slurry becomes a predetermined concentration according to the magnesium concentration in the leached slurry obtained.
  • the amount of sulfuric acid (the amount of sulfuric acid added) to be added to the ore slurry to be provided is adjusted.
  • the free sulfuric acid concentration is not particularly limited as long as it is in the above-mentioned range, and it is economically advantageous in consideration of valuable metals such as nickel and cobalt, sulfuric acid, and the price of the neutralizing agent. It is adjustable.
  • the addition amount of sulfuric acid may be adjusted so as to be the free sulfuric acid concentration in the corresponding leached slurry according to the correspondence as shown in Table 1 below, that is, the magnesium concentration in the leached slurry.
  • the free sulfuric acid concentration in the leached slurry when the magnesium concentration in the leached slurry is 10.0 g / L or more is the “reference value A”
  • the magnesium concentration in the leached slurry is 7.5 g / L or more. If it is less than 0 g / L, the amount of sulfuric acid added is adjusted so that the concentration of free sulfuric acid in the leached slurry is "standard value A-2.0 g / L".
  • the free sulfuric acid concentration in the leached slurry should be "reference value A-4.0 g / L”. Adjust the amount of sulfuric acid added.
  • the magnesium concentration in the leached slurry is less than 5.0 g / L, the amount of sulfuric acid added is adjusted so that the free sulfuric acid concentration in the leached slurry becomes "reference value A-6.0 g / L”. adjust.
  • the amount of added sulfuric acid is increased so as to increase the concentration of free sulfuric acid in order to keep the nickel leaching rate high.
  • the magnesium concentration in the leaching slurry is low, the nickel leaching rate can be maintained high even if the amount of added sulfuric acid is reduced.
  • the method for measuring the magnesium concentration in the leached slurry is not particularly limited, but ICP emission analysis and atomic absorption analysis are preferable in that the measurement results can be obtained rapidly. According to the measurement method by ICP emission spectrometry or atomic absorption spectrometry, even if the magnesium grade in the ore slurry fluctuates, the fluctuation can be detected from the magnesium concentration in the leached slurry, and the result is promptly determined according to the result. Adjustment of the amount of added sulfuric acid can be carried out so as to obtain an appropriate concentration of free sulfuric acid.
  • the amount of sulfuric acid used is effective while maintaining the leaching rate of valuable metals such as nickel at a high rate by adjusting the amount of sulfuric acid added according to the magnesium concentration in the leached slurry. Can be reduced to Thus, the leaching process can be efficiently performed, and the valuable metal nickel to be mainly leached can be effectively leached.
  • the concentration of free sulfuric acid in the obtained leaching slurry can be reduced, the amount of neutralizing agent used can be effectively reduced when neutralizing the free sulfuric acid in the pre-neutralization step S3 described later.
  • the pH of the leached slurry obtained in the leaching step S2 is adjusted to a predetermined range and subjected to neutralization treatment. Specifically, for example, the pH of the leaching slurry is adjusted to a desired range, that is, a range of about pH 2.8 to 3.2.
  • the leaching slurry obtained through the leaching step S2 contains excess sulfuric acid as free sulfuric acid as described above, and the pH is low.
  • the free sulfuric acid is neutralized by adding a neutralizing agent to the transferred leached slurry to adjust the pH to a predetermined range.
  • the leaching slurry can be charged into the neutralization treatment tank, and the neutralization treatment can be performed by adding a predetermined amount of the neutralizing agent to the leaching slurry in the tank.
  • the neutralization treatment tank for example, one consisting of only one treatment tank or one consisting of plural treatment tanks arranged in series can be used, and in the first treatment tank on the upstream side, the flush tank is used. Charge the leached slurry discharged from the neutralization treatment tank.
  • the amount of added sulfuric acid is adjusted according to the magnesium concentration in the leached slurry, and the concentration of free sulfuric acid in the obtained leached slurry Since the amount of neutralizing agent used in neutralizing the free sulfuric acid in the pre-neutralization step S3 can be effectively reduced.
  • Solid-Liquid Separation Step In the solid-liquid separation step S4, the leached slurry is mixed with the washing solution, and then solid-liquid separation treatment is performed using a solid-liquid separator such as thickener and the leachate containing valuable metals such as nickel and cobalt. Separate into (crude nickel sulfate aqueous solution) and leaching residue.
  • a solid-liquid separator such as thickener and the leachate containing valuable metals such as nickel and cobalt. Separate into (crude nickel sulfate aqueous solution) and leaching residue.
  • the leaching slurry is first diluted by the washing solution, and then the leaching residue in the leaching slurry is concentrated as a thickener of thickener.
  • nickel and cobalt adhering to the leaching residue can be reduced according to the degree of dilution.
  • nickel and cobalt recovery rates can be improved by connecting and using thickeners having such functions in multiple stages.
  • the pH of the obtained post-neutralization solution is 4 or less, preferably 3.0 to 3.5, more preferably 3. while suppressing the oxidation of the separated leachate.
  • a neutralizing agent such as calcium carbonate is added to the leaching solution so as to be 1 to 3.2, and a post-neutralization solution that is the source of a mother liquor for nickel recovery, and neutralization including trivalent iron as an impurity element Form a sediment slurry.
  • the leaching solution is subjected to neutralization treatment (purification treatment) in this manner to neutralize the excess acid used in the leaching treatment by the HPAL method to form a solution after neutralization, Impurities such as trivalent iron ions and aluminum ions remaining in the inside are removed as neutralized precipitates.
  • neutralization treatment purification treatment
  • the amount of the neutralizing agent used for the neutralization treatment in the neutralization step S5 is also It can be effectively reduced and efficient processing can be performed.
  • the solution after neutralization is a solution based on a leachate obtained by performing leaching treatment with sulfuric acid (leaching step S2), and is a sulfuric acid solution containing nickel and cobalt.
  • the solution after neutralization is the reaction start solution of the sulfurization reaction in the dezincification step S6 and the sulfurization step S7 described later, and the total concentration of the nickel concentration and the cobalt concentration is not particularly limited, but usually 2 g / L to 6 g It is the range of / L.
  • the nickel concentration is usually in the range of 2 g / L to 5 g / L
  • the cobalt concentration is usually in the range of 0.1 g / L to 0.6 g / L.
  • a sulfurizing agent such as hydrogen sulfide gas is added to the solution after neutralization obtained through the neutralization step S5 to sulfide the zinc contained in the solution after neutralization Separately remove in the form of goods.
  • the zinc sulfide formed by the sulfidation treatment with respect to the solution after neutralization is formed and separated and removed to obtain a nickel recovery mother liquor containing nickel and cobalt.
  • a solution after neutralization containing zinc as well as nickel and cobalt is introduced into a pressurized container, and hydrogen sulfide gas or the like is blown into the gas phase to make zinc zinc. And selectively sulfide to cobalt to form zinc sulfide and a nickel recovery mother liquor.
  • a nickel recovery mother liquor from which zinc has been separated can be obtained.
  • a sulfiding agent such as hydrogen sulfide gas is added to cause sulfidation reaction to form a mixed sulfide of nickel and cobalt.
  • the conditions for the sulfurization reaction the conditions are lower than the conditions for the sulfurization reaction for nickel.
  • the sulfiding agent such as hydrogen sulfide gas is blown into the initial solution of the sulfidation reaction, using the mother liquid for nickel recovery obtained through the dezincification step S6 as the initial solution of sulfidation reaction, to cause a sulfidation reaction, A sulfide (mixed sulfide) of nickel and cobalt containing few impurity components and a poor solution (liquid after sulfiding) stabilized at a low concentration of nickel or cobalt are formed.
  • the nickel recovery mother liquor is a sulfuric acid aqueous solution containing nickel and cobalt.
  • the sulfurization treatment in the sulfurization step S7 can be performed using a sulfurization reaction tank or the like, and hydrogen sulfide gas is blown into the gas phase part in the reaction tank to the sulfurization reaction start solution introduced into the sulfurization reaction tank to obtain a solution Sulfurization reaction is caused by dissolving hydrogen sulfide gas in the inside.
  • nickel and cobalt contained in the initial solution of the sulfidation reaction are immobilized as sulfide and recovered.
  • the obtained slurry containing nickel and cobalt sulfides is charged into a sedimentation separator such as thickener and subjected to sedimentation treatment, and only the sulfides are separated from the bottom of the thickener. to recover.
  • the aqueous solution component overflows from the top of the thickener and is recovered as a poor solution.
  • the metal content in the ore slurry was measured using a fluorescent X-ray analyzer, and the metal content in the leached slurry obtained by the leaching treatment was measured by ICP emission spectrometry. Also, the concentration of free sulfuric acid in the leached slurry was measured by a titration method. In addition, the leaching rate of nickel was calculated as [100 ⁇ (nickel grade in leached slurry, nickel grade in nickel ore slurry ore slurry) ⁇ 100 (%)].
  • Examples 1 to 3 An ore slurry was prepared from a raw material ore containing nickel, cobalt, iron, magnesium, zinc and the like, and this was charged into an autoclave, and then 98% sulfuric acid was added to perform leaching treatment under high temperature pressure.
  • the amount of added sulfuric acid is adjusted so that the free sulfuric acid concentration in the leached slurry is in the range of 40 g / L to 50 g / L. I made an adjustment.
  • the leaching conditions were as follows. Solid content ratio of ore slurry: 42% by weight to 45% by weight Magnesium grade of ore slurry: 0.8% by weight to 1.8% by weight ⁇ Flow rate of leaching slurry: 200 m 3 / hour to 250 m 3 / hour ⁇ Temperature in high temperature pressure reaction vessel: 240 ° C. to 260 ° C.
  • Table 2 below shows the nickel leaching rate and the amount of added sulfuric acid in Examples and Comparative Examples.
  • each numerical value in Table 2 is the average value of the day of the result of having extract
  • Example 2 As shown in the results of Table 2, in Examples 1 to 3 in which the amount of added sulfuric acid was adjusted according to the magnesium concentration in the leached slurry obtained by the leaching treatment, it was appropriate while maintaining a high nickel leaching rate. The treatment could be carried out with the amount of added sulfuric acid. In particular, also in Example 3 in which the magnesium grade in the ore slurry is high, it was possible to leach nickel at a high leaching rate.

Abstract

Provided is a leaching treatment method for nickel oxide ore, which is capable of effectively reducing the usage of sulfuric acid, while maintaining the high nickel leaching rate. A leaching treatment method according to the present invention obtains a leach slurry which is composed of a leachate that contains nickel and a leaching residue, by performing a leaching treatment by adding sulfuric acid into a slurry of nickel oxide ore containing magnesium (an ore slurry). In this leaching treatment method, the addition amount of the sulfuric acid is adjusted so that the free sulfuric acid concentration in a leach slurry that is obtained by the leaching treatment is at a predetermined value in accordance with the magnesium concentration in the leach slurry.

Description

浸出処理方法、ニッケル酸化鉱石の湿式製錬方法Leaching method, wet smelting method of nickel oxide ore
　本発明は、ニッケル酸化鉱石に対する浸出処理方法に関し、より詳しくは、ニッケル酸化鉱石のスラリーに対して硫酸を添加してニッケルを浸出させる浸出処理方法、及びその浸出処理方法を適用したニッケル酸化鉱石の湿式製錬方法に関する。 The present invention relates to a method of leaching treatment to nickel oxide ore, more specifically, a leaching treatment method of leaching nickel by adding sulfuric acid to a slurry of nickel oxide ore, and nickel oxide ore to which the leaching method is applied It relates to a hydrometallurgical process.
　ニッケル品位の低い低品位ニッケル酸化鉱石からニッケルやコバルト等の有価金属を湿式製錬により回収する方法として、例えば特許文献１に示すような、鉱石スラリーに硫酸を添加して高温加圧下で浸出する高温加圧酸浸出（ＨＰＡＬ：Ｈｉｇｈ　Ｐｒｅｓｓｕｒｅ　Ａｃｉｄ　Ｌｅａｃｈ）法が行われている。 As a method of recovering valuable metals such as nickel and cobalt from low grade nickel oxide ore with low nickel grade by wet smelting, sulfuric acid is added to ore slurry as shown in Patent Document 1, for example, and leached under high temperature pressurization The High Pressure Acid Leach (HPAL) method has been carried out.
　低品位ニッケル酸化鉱石には、鉄品位が高くマグネシウムやシリカ等のアルカリ成分品位の低いリモナイト（Ｌｉｍｏｎｉｔｅ）系鉱石と、アルカリ成分を多く含むサプロライト（Ｓａｐｒｏｌｉｔｅ）系鉱石の２つに大別され、ＨＰＡＬ法の原料としてはリモナイト系鉱石が主として用いられている。 The low grade nickel oxide ore is roughly classified into two: limonite ore with high iron grade and low alkali grade such as magnesium and silica, and Saprolite ore containing a large amount of alkali ingredient, HPAL Limonite ore is mainly used as a raw material of the method.
　さて、ＨＰＡＬ法では、ニッケル等の有価金属を高い浸出率で浸出させることは勿論、近年価格上昇の著しい硫酸の使用量を有効に低減させる方法が求められている。ＨＰＡＬ法における浸出処理では、ニッケルのほか、マグネシウム、アルミニウム、鉄、クロムといった、鉱石中に含まれている他の成分も浸出されることが知られており、特にマグネシウムは、そのほとんどが浸出されて多量の硫酸を消費してしまうため、経済的に好ましくない不純物である。 By the way, in the HPAL method, there is a demand for a method for effectively reducing the amount of sulfuric acid used in recent years, in which the price increase is significant, as well as for leaching valuable metals such as nickel at a high leaching rate. It is known that in the leaching process in the HPAL method, in addition to nickel, other components contained in the ore such as magnesium, aluminum, iron and chromium are also leached, and in particular, most of magnesium is leached. It is an economically undesirable impurity because it consumes a large amount of sulfuric acid.
　さらに、浸出処理においては、ニッケル及びマグネシウムの浸出反応が以下の反応式に示すように進行するため、例えば鉱石中のマグネシウム品位が高い場合には、下記（２）式の反応が優先的に進行して、ニッケルを浸出させる（１）式の反応を阻害してしまう。これにより、ニッケル浸出率の低下を招くという問題もある。
　ＮｉＯ＋Ｈ２ＳＯ４→ＮｉＳＯ４＋Ｈ２Ｏ　　・・・（１）
　ＭｇＯ＋Ｈ２ＳＯ４→ＭｇＳＯ４＋Ｈ２Ｏ　　・・・（２） Furthermore, in the leaching treatment, since the leaching reaction of nickel and magnesium proceeds as shown in the following reaction formula, for example, when the magnesium grade in the ore is high, the reaction of formula (2) below preferentially progresses As a result, the reaction of the formula (1) for leaching nickel is inhibited. There is also a problem that this causes a decrease in the nickel leaching rate.
NiO + H 2 SO 4 → NiSO 4 + H 2 O (1)
MgO + H 2 SO 4 → MgSO 4 + H 2 O (2)
　上述のように、ニッケル酸化鉱石には、ニッケル、コバルト等の有価金属の他に、不純物としてマグネシウムが含まれている。そのため、例えば、ニッケル酸化鉱石においてマグネシウム品位が高い場合には、浸出処理において目標とするニッケル浸出率を維持するために硫酸の添加量を増加させる必要がある。しかしながら、硫酸の添加量を増加させると、硫酸の原単位が増加してコスト高となるばかりか、浸出処理に使用する設備腐食の進行が速まるという問題がある。そのため、実操業においては、浸出反応後のスラリーに含まれる未反応の硫酸濃度（遊離硫酸濃度）を監視しており、遊離硫酸濃度が所定の範囲となるように硫酸の添加量を制御している。 As described above, nickel oxide ore contains magnesium as an impurity in addition to valuable metals such as nickel and cobalt. Therefore, for example, when the magnesium quality is high in the nickel oxide ore, it is necessary to increase the addition amount of sulfuric acid in order to maintain the target nickel leaching rate in the leaching process. However, when the amount of sulfuric acid added is increased, not only the basic unit of sulfuric acid is increased to increase the cost, but also there is a problem that the progress of equipment corrosion used for the leaching treatment is accelerated. Therefore, in actual operation, the unreacted sulfuric acid concentration (free sulfuric acid concentration) contained in the slurry after the leaching reaction is monitored, and the addition amount of sulfuric acid is controlled so that the free sulfuric acid concentration is within the predetermined range. There is.
　ニッケルの浸出反応の浸出率を高める手段として、遊離硫酸濃度や反応温度を上昇させる方法がある。しかしながら、硫酸消費量や、反応温度を高めるための蒸気等の熱エネルギー使用量が増加するという観点からすると、経済的には好ましくない。またそのほか、高いニッケル浸出率を得る手段として、二次浸出を行う方法（例えば特許文献２）等があるが、工程数が増加するため高効率操業という観点では望ましくない。 As a means to increase the leaching rate of the nickel leaching reaction, there is a method of increasing the concentration of free sulfuric acid and the reaction temperature. However, from the viewpoint of increasing the consumption of sulfuric acid and the amount of use of thermal energy such as steam for raising the reaction temperature, it is not economically preferable. In addition, as a means to obtain a high nickel leaching rate, there is a method of performing secondary leaching (for example, Patent Document 2), but this is not desirable from the viewpoint of high efficiency operation because the number of processes increases.
特開２００５－３５０７６６号公報JP 2005-350766 A 特表２００３－５１４１１０号公報Japanese Patent Publication No. 2003-514110
　本発明は、このような実情に鑑みて提案されたものであり、ニッケル酸化鉱石に対する浸出処理方法において、高いニッケル浸出率を維持しながら硫酸使用量を有効に低減させることができる方法を提供することを目的とする。 The present invention has been proposed in view of such circumstances, and provides a method capable of effectively reducing the amount of sulfuric acid used while maintaining a high nickel leaching rate, in a method of leaching treatment for nickel oxide ore. The purpose is
　本発明者は、上述した課題を解決するために鋭意検討を重ねた。その結果、鉱石スラリーに硫酸を添加して浸出処理を施す際、硫酸の添加量を、その浸出処理により得られる浸出スラリー中の金属成分の濃度、特にマグネシウムの濃度に応じて、浸出スラリー中の遊離硫酸濃度が所定の濃度となるように調整することで、高いニッケル浸出率を維持しながら硫酸使用量を有効に低減できることを見出し、本発明を完成するに至った。 The present inventors diligently studied to solve the problems described above. As a result, when sulfuric acid is added to the ore slurry to subject it to leaching treatment, the amount of sulfuric acid added depends on the concentration of metal components in the leaching slurry obtained by the leaching treatment, particularly the concentration of magnesium, in the leaching slurry. By adjusting the concentration of free sulfuric acid to a predetermined concentration, it is found that the amount of sulfuric acid used can be effectively reduced while maintaining a high nickel leaching rate, and the present invention has been completed.
　（１）本発明の第１の発明は、マグネシウムを含有するニッケル酸化鉱石のスラリー（鉱石スラリー）に対して硫酸を添加することによって浸出処理を施し、ニッケルを含む浸出液と浸出残渣とからなる浸出スラリーを得る浸出処理方法であって、前記硫酸の添加量を、浸出処理により得られる浸出スラリー中のマグネシウム濃度に応じて、該浸出スラリー中の遊離硫酸濃度が所定の濃度となるように調整する、浸出処理方法である。 (1) According to the first invention of the present invention, a leaching treatment is performed by adding sulfuric acid to a slurry of magnesium oxide-containing nickel oxide ore (ore slurry), and a leaching consisting of a leaching solution containing nickel and a leaching residue A leaching treatment method for obtaining a slurry, wherein the addition amount of the sulfuric acid is adjusted so that the concentration of free sulfuric acid in the leaching slurry becomes a predetermined concentration according to the magnesium concentration in the leaching slurry obtained by the leaching treatment. , Leaching method.
　（２）本発明の第２の発明は、第１の発明において、前記浸出スラリー中の遊離硫酸濃度が２５ｇ／Ｌ～５５ｇ／Ｌの範囲となるように、前記硫酸の添加量を調整する、浸出処理方法である。 (2) In the second invention of the present invention, in the first invention, the addition amount of the sulfuric acid is adjusted so that the concentration of free sulfuric acid in the leached slurry is in the range of 25 g / L to 55 g / L. It is a leaching method.
　（３）本発明の第３の発明は、第１の又は第２の発明において、前記浸出スラリー中のマグネシウム濃度を、ＩＣＰ発光分析法又は原子吸光分析法により測定する、浸出処理方法である。 (3) The third invention of the present invention is the leaching treatment method according to the first or second invention, wherein the magnesium concentration in the leaching slurry is measured by ICP emission spectrometry or atomic absorption spectrometry.
　（４）本発明の第４の発明は、ニッケル酸化鉱石から硫酸を用いてニッケルを含む有価金属を回収するニッケル酸化鉱石の湿式製錬方法であって、前記ニッケル酸化鉱石のスラリー（鉱石スラリー）に対して硫酸を添加することによって浸出処理を施し、ニッケルを含む浸出液と浸出残渣とからなる浸出スラリーを得る浸出工程を含み、前記浸出工程では、前記硫酸の添加量を、前記浸出処理により得られる浸出スラリー中のマグネシウム濃度に応じて、該浸出スラリー中の遊離硫酸濃度が所定の濃度となるように調整する、ニッケル酸化鉱石の湿式製錬方法である。 (4) A fourth invention of the present invention is a method for wet smelting nickel oxide ore in which valuable metal containing nickel is recovered from nickel oxide ore using sulfuric acid, wherein the slurry of nickel oxide ore (ore slurry) Are subjected to a leaching treatment by adding sulfuric acid thereto to obtain a leaching slurry consisting of a leaching solution containing nickel and a leaching residue, and in the leaching step, the addition amount of the sulfuric acid is obtained by the leaching treatment. And adjusting the concentration of free sulfuric acid in the leached slurry to a predetermined concentration in accordance with the concentration of magnesium in the leached slurry.
　本発明によれば、ニッケル酸化鉱石に対する浸出処理方法において、高いニッケル浸出率を維持しながら硫酸使用量を有効に低減させることができる。 According to the present invention, it is possible to effectively reduce the amount of sulfuric acid used while maintaining a high nickel leaching rate in the leaching treatment method for nickel oxide ore.
鉱石スラリー中のマグネシウム品位と、浸出スラリー中のマグネシウム濃度との相関関係を示すグラフである。It is a graph which shows correlation with magnesium grade in ore slurry, and magnesium concentration in leaching slurry. ニッケル酸化鉱石の湿式製錬方法の流れの一例を示した工程図である。It is the flowchart showing an example of the flow of the hydrometallurgy method of nickel oxide ore.
　以下、本発明の具体的な実施形態（以下、「本実施の形態」という）について詳細に説明する。本発明は以下の実施形態に限定されるものではなく、本発明の要旨を変更しない範囲で種々の変更が可能である。なお、本明細書において、「Ｘ～Ｙ」（Ｘ、Ｙは任意の数値）と表現する場合、特にことわらない限り「Ｘ以上Ｙ以下」であることを意味する。 Hereinafter, specific embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention. In the present specification, when expressing as “X to Y” (X and Y are arbitrary numerical values), it means “more than X and less than Y” unless otherwise specified.
　≪１．ニッケル酸化鉱石に対する浸出処理方法≫
　本実施の形態に係る浸出処理方法は、マグネシウムを含有するニッケル酸化鉱石のスラリー（鉱石スラリー）に対して硫酸を添加することによって浸出処理を施し、ニッケルを含む浸出液と浸出残渣とからなる浸出スラリーを得る方法である。この浸出処理方法は、例えば高温加圧容器（オートクレーブ）を用いて、高温加圧の環境下にて行われる。 << 1. Leaching method for nickel oxide ore >>
In the leaching method according to the present embodiment, leaching is performed by adding sulfuric acid to a slurry of nickel oxide ore containing magnesium (ore slurry), and a leaching slurry comprising a leachate containing nickel and a leaching residue How to get This leaching method is carried out in a high temperature and pressure environment using, for example, a high temperature pressure vessel (autoclave).
　具体的に、この浸出処理方法においては、鉱石スラリーに添加する硫酸の添加量を、浸出処理により得られる浸出スラリー中のマグネシウム濃度に応じて、浸出スラリー中の遊離硫酸濃度が所定の濃度となるように調整する。 Specifically, in this leaching treatment method, the amount of sulfuric acid added to the ore slurry is such that the concentration of free sulfuric acid in the leaching slurry becomes a predetermined concentration according to the magnesium concentration in the leaching slurry obtained by the leaching treatment To adjust.
　このような方法によれば、ニッケル酸化鉱石から高いニッケル浸出率を維持しながら、鉱石スラリーに添加する硫酸の添加量（使用量）を有効に低減することができる。これにより、処理に要するコストの上昇を防いで効率的な処理を可能とし、また、浸出処理に使用する設備（オートクレーブ）の腐食を抑えることもできる。また、硫酸使用量の低減に伴って、生成する浸出スラリー中の遊離硫酸濃度も有効に低減されることから、その遊離硫酸を中和するための中和剤使用量を低減させることもできる。 According to such a method, it is possible to effectively reduce the addition amount (use amount) of sulfuric acid to be added to the ore slurry while maintaining a high nickel leaching rate from the nickel oxide ore. This makes it possible to prevent the increase in cost for processing and enable efficient processing, and also to suppress corrosion of equipment (autoclave) used for the leaching processing. In addition, since the concentration of free sulfuric acid in the produced leaching slurry is effectively reduced along with the reduction of the amount of sulfuric acid used, the amount of neutralizing agent used to neutralize the free sulfuric acid can also be reduced.
　浸出処理の対象であるニッケル酸化鉱石としては、主としてリモナイト鉱及びサプロライト鉱等の、いわゆるラテライト鉱である。ラテライト鉱のニッケル含有量（含有率）は、通常、１．０質量％～２．０質量％程度であり、水酸化物又はケイ苦土（ケイ酸マグネシウム）鉱物として含有される。また、鉄の含有量は、１０質量％～５０質量％程度であり、主として３価の水酸化物（ゲーサイト）の形態であるが、一部２価の鉄がケイ苦土鉱物に含有される。また、ラテライト鉱のほかに、ニッケル、コバルト、マンガン、銅等の有価金属を含有する酸化鉱石、例えば深海底に賦存するマンガン瘤等が用いられる。 The nickel oxide ore to be subjected to the leaching treatment is mainly so-called laterite ore such as limonite or saprolite ore. The nickel content (content ratio) of laterite ore is usually about 1.0% by mass to about 2.0% by mass, and is contained as a hydroxide or a silica earth (magnesium silicate) mineral. The iron content is about 10% by mass to 50% by mass, and is mainly in the form of trivalent hydroxide (gesite), but a part of divalent iron is contained in siliceous earth mineral Ru. In addition to the laterite ore, oxide ores containing valuable metals such as nickel, cobalt, manganese, copper and the like, such as manganese lumps and the like stored in the deep sea floor are used.
　浸出処理に際しては、ニッケル酸化鉱石を所定の分級点で分級してオーバーサイズの鉱石粒子を除去した後に、アンダーサイズの鉱石粒子に水を添加して鉱石スラリーに調製し、調製した鉱石スラリーに対して硫酸を添加して浸出反応を生じさせる。鉱石スラリーの濃度としては、特に限定されないが、スラリー中の鉱石濃度が１５質量％～４５質量％程度になるように調製することが好ましい。スラリー濃度が１５質量％未満であると、浸出処理の際に同じ滞留時間を得るために大きな設備が必要となる。また、硫酸の添加量も相対的に増加する可能性がある。一方で、スラリー濃度が４５質量％を超えると、設備の規模は小さくできるものの、高濃度スラリーの搬送が困難になる（管内閉塞の頻発、エネルギーを要する等）という問題が生じる。 In the leaching process, nickel oxide ore is classified at a predetermined classification point to remove oversized ore particles, then water is added to the undersized ore particles to prepare an ore slurry, and the prepared ore slurry is prepared. Sulfuric acid is added to cause a leaching reaction. The concentration of the ore slurry is not particularly limited, but it is preferable to adjust the concentration of the ore in the slurry to about 15% by mass to 45% by mass. If the slurry concentration is less than 15% by mass, large equipment is required to obtain the same residence time during the leaching process. Also, the amount of sulfuric acid added may be relatively increased. On the other hand, when the slurry concentration exceeds 45% by mass, although the scale of the equipment can be reduced, the problem arises that the transport of the high concentration slurry becomes difficult (friction in the pipe frequently, energy is required, etc.).
　浸出処理においては、鉱石スラリーに対して高温加圧下で硫酸を添加することにより、下記の式（ｉ）～（ｖ）で表される浸出反応と高温熱加水分解反応によって、ニッケル、コバルト等の硫酸塩としての浸出と、浸出された硫酸鉄のヘマタイトとしての固定化が行われる。なお、鉄イオンの固定化は、完全には進行しないため、通常、得られる浸出スラリーの液部分には、ニッケル、コバルト等のほか、２価と３価の鉄イオンが含まれる。 In the leaching treatment, by adding sulfuric acid to the ore slurry under high temperature pressure, the leaching reaction and high temperature thermal hydrolysis reaction represented by the following formulas (i) to (v) Leaching as sulfate and immobilization of the leached iron sulfate as hematite are performed. In addition, since the immobilization of iron ions does not proceed completely, the liquid portion of the obtained leaching slurry usually contains divalent and trivalent iron ions in addition to nickel, cobalt and the like.
　（浸出反応）
ＭＯ＋Ｈ２ＳＯ４→ＭＳＯ４＋Ｈ２Ｏ　・・・（ｉ）
（式中Ｍは、Ｎｉ、Ｃｏ、Ｆｅ、Ｚｎ、Ｃｕ、Ｍｇ、Ｃｒ、Ｍｎ等を表す）
２ＦｅＯＯＨ＋３Ｈ２ＳＯ４→Ｆｅ２（ＳＯ４）３＋４Ｈ２Ｏ　・・・（ｉｉ）
ＦｅＯ＋Ｈ２ＳＯ４→ＦｅＳＯ４＋Ｈ２Ｏ　・・・（ｉｉｉ）
　（高温熱加水分解反応）
２ＦｅＳＯ４＋Ｈ２ＳＯ４＋１／２Ｏ２→Ｆｅ２（ＳＯ４）３＋Ｈ２Ｏ
　　　　　　　　　　　　　　　　　　　　　　　　　　・・・（ｉｖ）
Ｆｅ２（ＳＯ４）３＋３Ｈ２Ｏ→Ｆｅ２Ｏ３＋３Ｈ２ＳＯ４　・・・（ｖ） (Leaching reaction)
MO + H 2 SO 4 → MSO 4 + H 2 O (i)
(Wherein, M represents Ni, Co, Fe, Zn, Cu, Mg, Cr, Mn, etc.)
2FeOOH + 3H 2 SO 4 → Fe 2 (SO 4 ) 3 + 4H 2 O (ii)
FeO + H 2 SO 4 → FeSO 4 + H 2 O (iii)
(High temperature thermal hydrolysis reaction)
2FeSO 4 + H 2 SO 4 + 1 / 2O 2 → Fe 2 (SO 4 ) 3 + H 2 O
... (iv)
Fe 2 (SO 4 ) 3 + 3H 2 O → Fe 2 O 3 + 3H 2 SO 4 (v)
　浸出処理における温度（浸出反応温度）は、特に限定されないが、２２０℃～２８０℃程度であり、２４０℃～２７０℃程度であることが好ましい。このような温度範囲で反応させることにより、鉱石中の鉄の大部分をヘマタイトとして固定することができる。反応温度が２２０℃未満であると、高温熱加水分解反応の速度が遅くなるため、反応溶液中に鉄が溶存して残り、鉄を除去するための浄液負荷が増加する。また、鉄が溶存して残ることにより、溶存する鉄をその後の処理にて中和するための中和剤使用量が増加する。一方で、反応温度が２７０℃を超えると、高温熱加水分解反応自体は促進されるものの、高温加圧浸出に用いる反応容器の材質の選定が困難となり、また温度上昇にかかる熱エネルギーコストが上昇する。 The temperature (leaching reaction temperature) in the leaching treatment is not particularly limited, but is about 220 ° C. to 280 ° C., and preferably about 240 ° C. to 270 ° C. By reacting in such a temperature range, most of iron in the ore can be fixed as hematite. If the reaction temperature is less than 220 ° C., the rate of the high-temperature thermal hydrolysis reaction will be slow, and iron will remain dissolved in the reaction solution, increasing the solution load for removing iron. In addition, as iron is dissolved and remains, the amount of neutralizing agent used to neutralize the dissolved iron in the subsequent treatment increases. On the other hand, if the reaction temperature exceeds 270 ° C, although the high temperature thermal hydrolysis reaction itself is promoted, it becomes difficult to select the material of the reaction container used for high temperature pressure leaching, and the thermal energy cost for temperature rise rises. Do.
　浸出処理に用いる硫酸の添加量は、一般的には過剰量が用いられ、例えば鉱石１トン当り３００ｋｇ～４００ｋｇ程度の物量となる。鉱石スラリー中のマグネシウム品位が高い場合、このマグネシウムが浸出反応を起こすのに多くの硫酸を消費する。よって、ニッケルの浸出率を高く保つためには、浸出処理に用いる硫酸の添加量を増加させる必要がある。一方、鉱石スラリー中のマグネシウム品位が低い場合には、浸出処理に用いる硫酸の添加量を抑制しながらも、ニッケルの浸出率を高く保つことが望ましい。 The amount of addition of sulfuric acid used for the leaching treatment is generally an excess amount, for example, about 300 kg to 400 kg per ton of ore. When the magnesium grade in the ore slurry is high, this magnesium consumes a large amount of sulfuric acid to cause the leaching reaction. Therefore, in order to keep the leaching rate of nickel high, it is necessary to increase the addition amount of sulfuric acid used for the leaching treatment. On the other hand, when the magnesium grade in the ore slurry is low, it is desirable to keep the leaching rate of nickel high while suppressing the addition amount of sulfuric acid used for the leaching treatment.
　ここで、本発明者の研究により、図１に示すように、鉱石スラリー中のマグネシウム品位は、浸出スラリー中のマグネシウム濃度と強い相関関係を示すことが見出された。これは、上述したように、鉱石スラリーに含まれるマグネシウム成分が高温加圧条件下ではそのほとんどが浸出されるためであると考えられる。 Here, according to the study of the present inventor, as shown in FIG. 1, it was found that the magnesium grade in the ore slurry shows a strong correlation with the magnesium concentration in the leached slurry. This is considered to be because, as described above, most of the magnesium component contained in the ore slurry is leached under high temperature pressure conditions.
　そこで、本実施の形態においては、浸出処理において鉱石スラリーに添加する硫酸の量（添加量）に関して、その浸出処理により得られる浸出スラリー中のマグネシウム濃度に応じて調整する。具体的には、硫酸の添加量を、浸出処理により得られる浸出スラリー中のマグネシウム濃度に応じて、浸出スラリー中の遊離硫酸濃度が所定の濃度となるように調整する。例えば、浸出スラリー中のマグネシウム濃度に応じて、浸出スラリー中の遊離硫酸濃度が２５ｇ／Ｌ～５５ｇ／Ｌの範囲となるように、硫酸の添加量を調整する。 Therefore, in the present embodiment, the amount (addition amount) of sulfuric acid added to the ore slurry in the leaching process is adjusted according to the magnesium concentration in the leached slurry obtained by the leaching process. Specifically, the amount of added sulfuric acid is adjusted so that the concentration of free sulfuric acid in the leached slurry becomes a predetermined concentration, in accordance with the magnesium concentration in the leached slurry obtained by the leaching treatment. For example, according to the magnesium concentration in the leached slurry, the addition amount of sulfuric acid is adjusted so that the free sulfuric acid concentration in the leached slurry is in the range of 25 g / L to 55 g / L.
　このように、硫酸の添加量を、浸出処理により得られる浸出スラリー中のマグネシウム濃度に応じて調整することで、反応容器に供給される鉱石スラリー中のマグネシウム品位が変動しても、その変動を浸出スラリー中のマグネシウム濃度から的確に検出することができ、その結果に合わせて速やかにかつ柔軟に適正な遊離硫酸濃度に調整を実施することができる。これにより、ニッケルの浸出率の高く維持しながら、余剰な硫酸添加を抑制することができ、効率的に浸出処理を行うことができる。 Thus, by adjusting the addition amount of sulfuric acid according to the magnesium concentration in the leached slurry obtained by the leaching process, even if the magnesium grade in the ore slurry supplied to the reaction vessel fluctuates, the fluctuation is The concentration of magnesium in the leached slurry can be accurately detected, and the adjustment to the appropriate concentration of free sulfuric acid can be performed promptly and flexibly according to the result. Thereby, it is possible to suppress excess sulfuric acid addition while maintaining a high leaching rate of nickel, and it is possible to efficiently carry out the leaching treatment.
　浸出スラリー中のマグネシウム濃度は、例えば、ＩＣＰ発光分析法や原子吸光分析法により測定することができる。このような測定方法によれば、マグネシウム濃度を迅速に測定することができ、好ましい。また、このように迅速にマグネシウム濃度を測定できることから、鉱石スラリー中のマグネシウム品位が変動した場合でも、その変動を浸出スラリー中のマグネシウム濃度から即座に検出することができ、その結果に合わせて速やかに遊離硫酸濃度の調整を行うことができる。 The magnesium concentration in the leached slurry can be measured, for example, by ICP emission spectrometry or atomic absorption spectrometry. According to such a measurement method, the magnesium concentration can be rapidly measured, which is preferable. In addition, since the magnesium concentration can be measured rapidly in this way, even if the magnesium grade in the ore slurry fluctuates, the fluctuation can be detected immediately from the magnesium concentration in the leached slurry, and according to the result, it is promptly It is possible to adjust the concentration of free sulfuric acid to
　なお、例えば、浸出処理に供される鉱石スラリー中のマグネシウム品位を測定し、その鉱石スラリー中のマグネシウム品位見合いで、浸出スラリー中の遊離硫酸濃度が適性の範囲となるように硫酸添加量を調整するという方法も考えられる。しかしながら、一般的に、鉱石スラリーのマグネシウム品位の測定には蛍光Ｘ線分析方法が用いられ、その蛍光Ｘ線分析方法による測定では、試料調製を含めて、試料採取から測定結果が得られるまでにおよそ８時間程度の長時間を要することとなる。そのため、測定結果が得られる頃には、既に鉱石スラリー貯槽内の鉱石スラリーが入れ替わっており、オートクレーブへの硫酸添加量が、実際に供給される鉱石スラリーのマグネシウム品位に対して適切ではないという可能性が考えられる。 In addition, for example, the magnesium grade in the ore slurry to be subjected to leaching treatment is measured, and the amount of added sulfuric acid is adjusted so that the free sulfuric acid concentration in the leached slurry becomes the appropriate range by the magnesium grade in the ore slurry. It is also conceivable to do this. However, in general, a fluorescent X-ray analysis method is used to measure the magnesium quality of the ore slurry, and in the measurement by the fluorescent X-ray analysis method, including the sample preparation, until the measurement results are obtained It will take a long time of about 8 hours. Therefore, by the time the measurement results are obtained, the ore slurry in the ore slurry storage tank has already been replaced, and it is possible that the amount of sulfuric acid added to the autoclave is not appropriate for the magnesium grade of the actually supplied ore slurry. Sex is considered.
　これに対して、浸出スラリー中のマグネシウム濃度に応じて硫酸添加量を調整することで、上述したようにＩＣＰ発光分析法や原子吸光分析法等の測定方法により、迅速にかつ適切にマグネシウム濃度を測定できることから、鉱石スラリー中のマグネシウム品位が変動した場合でも、浸出スラリー中の遊離硫酸濃度が適正な範囲となるように、速やかに硫酸添加量を調整ことができる。 On the other hand, by adjusting the amount of added sulfuric acid according to the magnesium concentration in the leached slurry, the magnesium concentration can be promptly and appropriately determined by the measurement method such as ICP emission analysis or atomic absorption analysis as described above. Since it can be measured, even when the magnesium grade in the ore slurry fluctuates, the amount of added sulfuric acid can be promptly adjusted so that the concentration of free sulfuric acid in the leached slurry is in an appropriate range.
　浸出スラリー中の遊離硫酸濃度とは、浸出終了時の遊離硫酸の濃度であり、特に限定されないが、２５ｇ／Ｌ～５５ｇ／Ｌ程度であることが好ましく、３４ｇ／Ｌ～５０ｇ／Ｌ程度であることがより好ましい。このような遊離硫酸濃度となるように硫酸の添加量を調整することで、マグネシウムが含まれるニッケル酸化鉱石から高い浸出率でニッケルを浸出させることができる。また、このような遊離硫酸濃度であれば、真密度の高い浸出残渣を安定的に生成させ、浸出スラリーの固液分離性を向上させることもできる。 The free sulfuric acid concentration in the leached slurry is the concentration of free sulfuric acid at the end of leaching, and is not particularly limited, but is preferably about 25 g / L to 55 g / L, and about 34 g / L to 50 g / L. Is more preferred. By adjusting the addition amount of sulfuric acid so as to obtain such a free sulfuric acid concentration, it is possible to leach nickel at a high leaching rate from the nickel oxide ore containing magnesium. Moreover, if it is such a free sulfuric acid concentration, the leaching residue with high true density can be produced | generated stably, and the solid-liquid separation property of a leaching slurry can also be improved.
　浸出スラリー中の遊離硫酸濃度が２５ｇ／Ｌ未満である場合は、浸出残渣を含むスラリーを沈降操作にかけた場合、固形分が十分に濃縮されず、あるいは上澄みにＳＳ分が多く存在するようになる。これは、高温熱加水分解の反応速度が遅く、水酸化鉄の脱水が十分に進まず、真密度の低いヘマタイトが形成されることによると考えられる。一方で、浸出スラリー中の遊離硫酸濃度が５５ｇ／Ｌを超えると、硫酸量が過剰な状態となり、硫酸使用量が増加してしまうとともに、後工程においてその遊離酸を中和するための中和剤の使用量も増加することとなり、効率的な処理を行うことができない。また、浸出処理設備（オートクレーブ）の耐久性を高めることが必要となる。 When the concentration of free sulfuric acid in the leaching slurry is less than 25 g / L, when the slurry containing the leaching residue is subjected to a sedimentation operation, the solid content is not sufficiently concentrated or a large amount of SS is present in the supernatant . This is considered to be due to the fact that the reaction rate of high temperature thermal hydrolysis is slow, dehydration of iron hydroxide does not proceed sufficiently, and hematite with low true density is formed. On the other hand, when the concentration of free sulfuric acid in the leached slurry exceeds 55 g / L, the amount of sulfuric acid becomes excessive, and the amount of sulfuric acid used increases, and the neutralization for neutralizing the free acid in a later step The amount of agent used also increases, and efficient processing can not be performed. In addition, it is necessary to enhance the durability of the leaching treatment facility (autoclave).
　以上のように、本実施の形態に係る浸出処理方法は、浸出処理により得られる浸出スラリー中のマグネシウム濃度を定期的にモニタリングしておき、そのマグネシウム濃度に応じて、浸出処理に供される鉱石スラリーへの硫酸の添加量を調整する。これにより、ニッケル浸出率を高い割合で維持しながら、硫酸の使用量を有効に低減できる。 As described above, in the leaching method according to the present embodiment, the magnesium concentration in the leached slurry obtained by the leaching treatment is periodically monitored, and the ore to be subjected to the leaching treatment according to the magnesium concentration. Adjust the amount of sulfuric acid added to the slurry. This makes it possible to effectively reduce the amount of sulfuric acid used while maintaining a high nickel leaching rate.
　なお、浸出反応の進行度合いは、排出される浸出残渣中のニッケル品位をモニタリングすることによって行うことができ、そのニッケル品位に応じて、遊離硫酸濃度の細かい調整を実施することが望ましい。 The degree of progress of the leaching reaction can be performed by monitoring the grade of nickel in the leached residue discharged, and it is desirable to finely adjust the concentration of free sulfuric acid according to the grade of nickel.
　≪２．ニッケル酸化鉱石の湿式製錬方法≫
　次に、上述した浸出処理方法を適用した、ニッケル酸化鉱石の湿式製錬方法について説明する。なお、ニッケル酸化鉱石の湿式製錬方法は、高温加圧下で浸出を行う高温加圧酸浸出法（ＨＰＡＬ法）による湿式製錬方法である。 << 2. Wet smelting method of nickel oxide ore ≫
Next, a wet smelting method of nickel oxide ore to which the above-mentioned leaching method is applied will be described. In addition, the wet refining method of a nickel oxide ore is a wet refining method by the high temperature pressure acid leaching method (HPAL method) which leaches under high temperature pressurization.
　図２は、ニッケル酸化鉱石の湿式製錬方法の流れの一例を示した工程図である。ニッケル酸化鉱石の湿式製錬方法は、原料のニッケル酸化鉱石を解砕分級して鉱石スラリーを調製する鉱石スラリー化工程Ｓ１と、鉱石スラリーに硫酸を添加して高温加圧下で浸出処理を施し浸出スラリーを得る浸出工程Ｓ２と、浸出スラリーのｐＨを調整して遊離硫酸を部分的に中和する予備中和工程Ｓ３と、浸出スラリーから浸出残渣を分離してニッケル及びコバルトを含む浸出液を得る固液分離工程Ｓ４と、浸出液のｐＨを調整して不純物元素を中和澱物スラリーとして分離する中和工程Ｓ５と、中和後液に硫化剤を添加することで亜鉛硫化物を生成させて分離除去し、ニッケル及びコバルトを含むニッケル回収用母液を得る脱亜鉛工程Ｓ６と、ニッケル回収用母液に硫化剤を添加することでニッケル及びコバルトの混合硫化物を得る硫化工程Ｓ７と、を有する。 FIG. 2 is a process diagram showing an example of the flow of the hydrometallurgical method of nickel oxide ore. The wet smelting method of nickel oxide ore is the ore slurrying step S1 of crushing or classifying the raw material nickel oxide ore to prepare ore slurry, and adding sulfuric acid to the ore slurry to apply leaching treatment under high temperature pressure and leaching A leaching step S2 for obtaining a slurry, a pre-neutralization step S3 for partially neutralizing free sulfuric acid by adjusting the pH of the leached slurry, and separation of leaching residue from the leached slurry to obtain a leachate containing nickel and cobalt Liquid separation process S4, neutralization process S5 which adjusts the pH of the leachate to separate impurity elements as neutralized sediment slurry, and addition of a sulfurizing agent to the solution after neutralization produces zinc sulfide and separation Dezincification step S6 to obtain nickel and cobalt-containing mother liquor by removing nickel and cobalt, and adding a sulfiding agent to the nickel recovery mother liquor to obtain mixed sulfide of nickel and cobalt A reduction and step S7, the.
　（１）鉱石スラリー化工程
　鉱石スラリー化工程Ｓ１は、原料鉱石であるニッケル酸化鉱石から鉱石スラリーを調製する工程であり、いわゆる浸出処理（浸出工程Ｓ２）の前処理工程である。具体的に、鉱石スラリー化工程Ｓ１では、所定の分級点で分級してオーバーサイズの鉱石粒子を除去した後に、アンダーサイズの鉱石粒子に水を添加することで鉱石スラリーを調製する。 (1) Ore Slurrying Step The ore slurrying step S1 is a step of preparing an ore slurry from nickel oxide ore which is a raw material ore, and is a pretreatment step of so-called leaching treatment (leaching step S2). Specifically, in the ore slurrying step S1, after sorting at a predetermined classification point to remove oversized ore particles, water is added to the undersized ore particles to prepare an ore slurry.
　ニッケル酸化鉱石の分級方法は、所望とする粒径に基づいて分級できれば特に限定されず、グリズリーや振動篩等を用いた篩分けによって行うことができる。また、その分級点についても、所望とする粒径値以下の鉱石粒子からなる鉱石スラリーを得るための分級点を適宜設定することができる。 The classification method of the nickel oxide ore is not particularly limited as long as it can be classified based on the desired particle size, and can be performed by sieving using a grizzly or a vibrating screen. Further, with regard to the classification point, a classification point for obtaining an ore slurry composed of ore particles having a particle diameter value or less desired can be appropriately set.
　ニッケル酸化鉱石としては、上述したように、リモナイト鉱及びサプロライト鉱等のいわゆるラテライト鉱を用いることができる。ラテライト鉱のニッケル含有率は、通常、１．０重量％～２．０重量％程度である。また、この原料鉱石であるニッケル酸化鉱石には、不純物としてマグネシウムが所定の割合で含まれている。 As the nickel oxide ore, as described above, so-called laterite ore such as limonite ore and saprolite ore can be used. The nickel content of laterite ore is usually about 1.0% by weight to 2.0% by weight. Moreover, in the nickel oxide ore which is the raw material ore, magnesium is contained as a impurity at a predetermined ratio.
　（２）浸出工程
　浸出工程Ｓ２は、鉱石スラリーに高温加圧下で硫酸を添加して、鉱石中のニッケル等の有価金属を浸出させる工程である。具体的に、浸出工程Ｓ２では、オートクレーブを用い、鉱石スラリーに硫酸を添加して、温度２２０℃～２８０℃程度、圧力３ＭＰａ～５ＭＰａ程度の条件下で撹拌し、浸出液と浸出残渣とからなる浸出スラリーを生成させる。 (2) Leaching process Leaching process S2 is a process of adding sulfuric acid to ore slurry under high temperature pressurization, and leaching valuable metals, such as nickel in ore. Specifically, in the leaching step S2, sulfuric acid is added to the ore slurry using an autoclave, and stirring is performed under the conditions of a temperature of about 220 ° C. to 280 ° C. and a pressure of about 3 MPa to 5 MPa. Generate a slurry.
　ここで、本実施の形態においては、浸出工程Ｓ２での浸出処理に際して、得られる浸出スラリー中のマグネシウム濃度に応じて、その浸出スラリー中の遊離硫酸濃度が所定の濃度となるように、浸出処理に供される鉱石スラリーに添加する硫酸の量（硫酸添加量）を調整することを特徴としている。遊離硫酸濃度については、上述した範囲であれば、特に限定されるものではなく、ニッケル、コバルト等の有価金属、硫酸、及び中和剤の価格等を考慮して経済的に有利になるように調整可能である。 Here, in the present embodiment, in the leaching process in the leaching step S2, the leaching process is carried out so that the concentration of free sulfuric acid in the leached slurry becomes a predetermined concentration according to the magnesium concentration in the leached slurry obtained. The amount of sulfuric acid (the amount of sulfuric acid added) to be added to the ore slurry to be provided is adjusted. The free sulfuric acid concentration is not particularly limited as long as it is in the above-mentioned range, and it is economically advantageous in consideration of valuable metals such as nickel and cobalt, sulfuric acid, and the price of the neutralizing agent. It is adjustable.
　例えば、下記表１に示すような対応関係、つまり、浸出スラリー中のマグネシウム濃度に応じて、対応する浸出スラリー中の遊離硫酸濃度となるように、硫酸の添加量を調整すればよい。具体的には、浸出スラリー中のマグネシウム濃度が１０．０ｇ／Ｌ以上のときの浸出スラリー中の遊離硫酸濃度を「基準値Ａ」として、浸出スラリー中のマグネシウム濃度が７．５ｇ／Ｌ以上１０．０ｇ／Ｌ未満である場合には、浸出スラリー中の遊離硫酸濃度が「基準値Ａ－２．０ｇ／Ｌ」となるように、硫酸の添加量を調整する。また、浸出スラリー中のマグネシウム濃度が５．０ｇ／Ｌ以上７．５ｇ／Ｌ未満である場合には、浸出スラリー中の遊離硫酸濃度が「基準値Ａ－４．０ｇ／Ｌ」となるように、硫酸の添加量を調整する。また、浸出スラリー中のマグネシウム濃度が５．０ｇ／Ｌ未満である場合には、浸出スラリー中の遊離硫酸濃度が「基準値Ａ－６．０ｇ／Ｌ」となるように、硫酸の添加量を調整する。 For example, the addition amount of sulfuric acid may be adjusted so as to be the free sulfuric acid concentration in the corresponding leached slurry according to the correspondence as shown in Table 1 below, that is, the magnesium concentration in the leached slurry. Specifically, the free sulfuric acid concentration in the leached slurry when the magnesium concentration in the leached slurry is 10.0 g / L or more is the “reference value A”, and the magnesium concentration in the leached slurry is 7.5 g / L or more. If it is less than 0 g / L, the amount of sulfuric acid added is adjusted so that the concentration of free sulfuric acid in the leached slurry is "standard value A-2.0 g / L". Also, when the magnesium concentration in the leached slurry is 5.0 g / L or more and less than 7.5 g / L, the free sulfuric acid concentration in the leached slurry should be "reference value A-4.0 g / L". Adjust the amount of sulfuric acid added. In addition, when the magnesium concentration in the leached slurry is less than 5.0 g / L, the amount of sulfuric acid added is adjusted so that the free sulfuric acid concentration in the leached slurry becomes "reference value A-6.0 g / L". adjust.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　このように、得られる浸出スラリー中のマグネシウム濃度が高い場合には、ニッケル浸出率を高く保つために、遊離硫酸濃度が高くなるように、硫酸添加量を増加させる。一方で、浸出スラリー中のマグネシウム濃度が低い場合には、硫酸添加量を低減してもニッケル浸出率を高く維持することが可能であることから、遊離硫酸濃度が低くなるように、硫酸添加量を減少させる。 Thus, when the magnesium concentration in the obtained leaching slurry is high, the amount of added sulfuric acid is increased so as to increase the concentration of free sulfuric acid in order to keep the nickel leaching rate high. On the other hand, when the magnesium concentration in the leaching slurry is low, the nickel leaching rate can be maintained high even if the amount of added sulfuric acid is reduced. Reduce
　浸出スラリー中のマグネシウム濃度の測定方法については、特に限定されないが、測定結果が迅速に得られる点から、ＩＣＰ発光分析法や原子吸光分析法が好ましい。ＩＣＰ発光分析法や原子吸光分析法による測定方法によれば、鉱石スラリー中のマグネシウム品位が変動しても、その変動を浸出スラリー中のマグネシウム濃度から検出することができ、その結果に合わせて速やかに適正な遊離硫酸濃度となるように硫酸添加量の調整を実施することができる。 The method for measuring the magnesium concentration in the leached slurry is not particularly limited, but ICP emission analysis and atomic absorption analysis are preferable in that the measurement results can be obtained rapidly. According to the measurement method by ICP emission spectrometry or atomic absorption spectrometry, even if the magnesium grade in the ore slurry fluctuates, the fluctuation can be detected from the magnesium concentration in the leached slurry, and the result is promptly determined according to the result. Adjustment of the amount of added sulfuric acid can be carried out so as to obtain an appropriate concentration of free sulfuric acid.
　このように、浸出処理においては、浸出スラリー中のマグネシウム濃度に応じて硫酸の添加量を調整することで、ニッケル等の有価金属の浸出率を高い割合で維持しながら、硫酸の使用量を有効に低減できる。これにより、効率的に浸出処理を施すことができるとともに、主たる浸出対象である有価金属のニッケルを効果的に浸出させることができる。また、得られた浸出スラリー中の遊離硫酸濃度を低減できることから、後述する予備中和工程Ｓ３にて遊離硫酸を中和する際の中和剤使用量も有効に低減させることができる。 Thus, in the leaching process, the amount of sulfuric acid used is effective while maintaining the leaching rate of valuable metals such as nickel at a high rate by adjusting the amount of sulfuric acid added according to the magnesium concentration in the leached slurry. Can be reduced to Thus, the leaching process can be efficiently performed, and the valuable metal nickel to be mainly leached can be effectively leached. In addition, since the concentration of free sulfuric acid in the obtained leaching slurry can be reduced, the amount of neutralizing agent used can be effectively reduced when neutralizing the free sulfuric acid in the pre-neutralization step S3 described later.
　（３）予備中和工程
　予備中和工程Ｓ３では、浸出工程Ｓ２にて得られた浸出スラリーのｐＨを所定範囲に調整して中和処理を施す。具体的には、例えば、浸出スラリーのｐＨを、所望とする範囲である、ｐＨ２．８～３．２程度の範囲に調整する。 (3) Pre-neutralization step In the pre-neutralization step S3, the pH of the leached slurry obtained in the leaching step S2 is adjusted to a predetermined range and subjected to neutralization treatment. Specifically, for example, the pH of the leaching slurry is adjusted to a desired range, that is, a range of about pH 2.8 to 3.2.
　浸出工程Ｓ２を経て得られた浸出スラリーには、上述したように、余剰の硫酸が遊離硫酸として含まれており、そのｐＨは低い。予備中和工程Ｓ３では、移送された浸出スラリーに中和剤を添加してｐＨを所定範囲に調整することによって、遊離硫酸を中和する。 The leaching slurry obtained through the leaching step S2 contains excess sulfuric acid as free sulfuric acid as described above, and the pH is low. In the pre-neutralization step S3, the free sulfuric acid is neutralized by adding a neutralizing agent to the transferred leached slurry to adjust the pH to a predetermined range.
　予備中和工程Ｓ３では、例えば中和処理槽に浸出スラリーを装入して、槽内の浸出スラリーに所定量の中和剤を添加することによって中和処理を行うことができる。中和処理槽としては、例えば１段の処理槽のみからなるもの、あるいは直列に並べた複数段の処理槽から構成されるものを用いることができ、上流側の最初の処理槽に、フラッシュタンクから排出された浸出スラリーを装入する。 In the preliminary neutralization step S3, for example, the leaching slurry can be charged into the neutralization treatment tank, and the neutralization treatment can be performed by adding a predetermined amount of the neutralizing agent to the leaching slurry in the tank. As the neutralization treatment tank, for example, one consisting of only one treatment tank or one consisting of plural treatment tanks arranged in series can be used, and in the first treatment tank on the upstream side, the flush tank is used. Charge the leached slurry discharged from the
　なお、上述したように、本実施の形態では、浸出工程Ｓ２での浸出処理において、浸出スラリー中のマグネシウム濃度に応じて硫酸の添加量を調整しており、得られる浸出スラリー中の遊離硫酸濃度も有効に低減できることから、この予備中和工程Ｓ３にて遊離硫酸を中和する際の中和剤使用量を有効に低減させることができる。 As described above, in the present embodiment, in the leaching process in the leaching step S2, the amount of added sulfuric acid is adjusted according to the magnesium concentration in the leached slurry, and the concentration of free sulfuric acid in the obtained leached slurry Since the amount of neutralizing agent used in neutralizing the free sulfuric acid in the pre-neutralization step S3 can be effectively reduced.
　（４）固液分離工程
　固液分離工程Ｓ４では、浸出スラリーを洗浄液と混合した後、シックナー等の固液分離装置を用いて固液分離処理を施し、ニッケルやコバルト等の有価金属を含む浸出液（粗硫酸ニッケル水溶液）と浸出残渣とに分離する。 (4) Solid-Liquid Separation Step In the solid-liquid separation step S4, the leached slurry is mixed with the washing solution, and then solid-liquid separation treatment is performed using a solid-liquid separator such as thickener and the leachate containing valuable metals such as nickel and cobalt. Separate into (crude nickel sulfate aqueous solution) and leaching residue.
　具体的には、先ず、浸出スラリーが洗浄液により希釈され、次に、浸出スラリー中の浸出残渣がシックナーの沈降物として濃縮される。これにより、浸出残渣に付着するニッケルやコバルトをその希釈度合に応じて減少させることができる。実操業では、このような機能を持つシックナーを多段に連結して用いることにより、ニッケル及びコバルトの回収率の向上を図ることができる。 Specifically, the leaching slurry is first diluted by the washing solution, and then the leaching residue in the leaching slurry is concentrated as a thickener of thickener. Thereby, nickel and cobalt adhering to the leaching residue can be reduced according to the degree of dilution. In actual operation, nickel and cobalt recovery rates can be improved by connecting and using thickeners having such functions in multiple stages.
　（５）中和工程
　中和工程Ｓ５では、分離された浸出液の酸化を抑制しながら、得られる中和後液のｐＨが４以下、好ましくは３．０～３．５、より好ましくは３．１～３．２になるように、その浸出液に炭酸カルシウム等の中和剤を添加し、ニッケル回収用の母液の元となる中和後液と、不純物元素として３価の鉄を含む中和澱物スラリーとを形成する。 (5) Neutralization Step In the neutralization step S5, the pH of the obtained post-neutralization solution is 4 or less, preferably 3.0 to 3.5, more preferably 3. while suppressing the oxidation of the separated leachate. A neutralizing agent such as calcium carbonate is added to the leaching solution so as to be 1 to 3.2, and a post-neutralization solution that is the source of a mother liquor for nickel recovery, and neutralization including trivalent iron as an impurity element Form a sediment slurry.
　中和工程Ｓ５では、このように浸出液に対する中和処理（浄液処理）を施すことで、ＨＰＡＬ法による浸出処理で用いた過剰の酸を中和して中和後液を生成するとともに、溶液中に残留する３価の鉄イオンやアルミニウムイオン等の不純物を中和澱物として除去する。このとき、本実施の形態では、浸出工程Ｓ２において浸出スラリー中の遊離硫酸濃度を有効に低減させるようにしていることから、中和工程Ｓ５における中和処理に使用する中和剤の量についても有効に低減させることができ、効率的な処理を行うことができる。 In the neutralization step S5, the leaching solution is subjected to neutralization treatment (purification treatment) in this manner to neutralize the excess acid used in the leaching treatment by the HPAL method to form a solution after neutralization, Impurities such as trivalent iron ions and aluminum ions remaining in the inside are removed as neutralized precipitates. At this time, in the present embodiment, since the concentration of free sulfuric acid in the leaching slurry is effectively reduced in the leaching step S2, the amount of the neutralizing agent used for the neutralization treatment in the neutralization step S5 is also It can be effectively reduced and efficient processing can be performed.
　なお、中和後液は、硫酸による浸出処理（浸出工程Ｓ２）を施して得られた浸出液に基づく溶液であって、ニッケル及びコバルトを含む硫酸酸性溶液である。この中和後液は、後述する脱亜鉛工程Ｓ６、硫化工程Ｓ７における硫化反応の反応始液となるものであり、ニッケル濃度及びコバルト濃度の合計濃度は特に限定されないが、通常２ｇ／Ｌ～６ｇ／Ｌの範囲である。ニッケル濃度は通常２ｇ／Ｌ～５ｇ／Ｌの範囲であり、コバルト濃度は通常０．１ｇ／Ｌ～０．６ｇ／Ｌの範囲である。 The solution after neutralization is a solution based on a leachate obtained by performing leaching treatment with sulfuric acid (leaching step S2), and is a sulfuric acid solution containing nickel and cobalt. The solution after neutralization is the reaction start solution of the sulfurization reaction in the dezincification step S6 and the sulfurization step S7 described later, and the total concentration of the nickel concentration and the cobalt concentration is not particularly limited, but usually 2 g / L to 6 g It is the range of / L. The nickel concentration is usually in the range of 2 g / L to 5 g / L, and the cobalt concentration is usually in the range of 0.1 g / L to 0.6 g / L.
　（６）脱亜鉛工程
　脱亜鉛工程Ｓ６では、中和工程Ｓ５を経て得られた中和後液に硫化水素ガス等の硫化剤を添加することによって、中和後液中に含まれる亜鉛を硫化物の形態として分離除去する。このように、中和後液に対する硫化処理により生成した亜鉛硫化物を生成させ、それを分離除去することで、ニッケル及びコバルトを含むニッケル回収用母液を得る。 (6) Dezincification Step In the dezincification step S6, a sulfurizing agent such as hydrogen sulfide gas is added to the solution after neutralization obtained through the neutralization step S5 to sulfide the zinc contained in the solution after neutralization Separately remove in the form of goods. Thus, the zinc sulfide formed by the sulfidation treatment with respect to the solution after neutralization is formed and separated and removed to obtain a nickel recovery mother liquor containing nickel and cobalt.
　具体的に、脱亜鉛工程Ｓ６では、例えば、加圧された容器内にニッケル及びコバルトと共に亜鉛を含む中和後液を導入し、気相中へ硫化水素ガス等を吹き込むことによって、亜鉛をニッケル及びコバルトに対して選択的に硫化し、亜鉛硫化物とニッケル回収用母液とを生成する。硫化反応後に得られたスラリーを固液分離することにより、亜鉛を分離したニッケル回収用母液を得ることができる。 Specifically, in the dezincification step S6, for example, a solution after neutralization containing zinc as well as nickel and cobalt is introduced into a pressurized container, and hydrogen sulfide gas or the like is blown into the gas phase to make zinc zinc. And selectively sulfide to cobalt to form zinc sulfide and a nickel recovery mother liquor. By solid-liquid separation of the slurry obtained after the sulfurization reaction, a nickel recovery mother liquor from which zinc has been separated can be obtained.
　なお、次工程の硫化工程（ニッケル回収工程）においても、硫化水素ガス等の硫化剤を添加して硫化反応を生じさせることによってニッケル及びコバルトの混合硫化物を生成させるが、そのニッケル等の硫化処理に先立って行う脱亜鉛処理では、硫化反応の条件として、ニッケルに対する硫化反応条件よりも緩和させた条件で行う。 In addition, in the next step of sulfiding (nickel recovery step), a sulfiding agent such as hydrogen sulfide gas is added to cause sulfidation reaction to form a mixed sulfide of nickel and cobalt. In the dezincification treatment to be performed prior to the treatment, as the conditions for the sulfurization reaction, the conditions are lower than the conditions for the sulfurization reaction for nickel.
　（７）硫化工程（ニッケル回収工程）
　硫化工程Ｓ７では、脱亜鉛工程Ｓ６を経て得られたニッケル回収用母液を硫化反応始液として、その硫化反応始液に対して硫化水素ガス等の硫化剤を吹き込むことにより硫化反応を生じさせ、不純物成分の少ないニッケル及びコバルトの硫化物（混合硫化物）と、ニッケルやコバルトの濃度を低い水準で安定させた貧液（硫化後液）とを生成させる。なお、ニッケル回収用母液は、ニッケル及びコバルトを含む硫酸水溶液である。 (7) Sulfurization process (nickel recovery process)
In the sulfidation step S7, the sulfiding agent such as hydrogen sulfide gas is blown into the initial solution of the sulfidation reaction, using the mother liquid for nickel recovery obtained through the dezincification step S6 as the initial solution of sulfidation reaction, to cause a sulfidation reaction, A sulfide (mixed sulfide) of nickel and cobalt containing few impurity components and a poor solution (liquid after sulfiding) stabilized at a low concentration of nickel or cobalt are formed. The nickel recovery mother liquor is a sulfuric acid aqueous solution containing nickel and cobalt.
　硫化工程Ｓ７における硫化処理は、硫化反応槽等を用いて行うことができ、硫化反応槽に導入した硫化反応始液に対して、その反応槽内の気相部分に硫化水素ガスを吹き込み、溶液中に硫化水素ガスを溶解させることで硫化反応を生じさせる。この硫化処理により、硫化反応始液中に含まれるニッケル及びコバルトを硫化物として固定化して回収する。 The sulfurization treatment in the sulfurization step S7 can be performed using a sulfurization reaction tank or the like, and hydrogen sulfide gas is blown into the gas phase part in the reaction tank to the sulfurization reaction start solution introduced into the sulfurization reaction tank to obtain a solution Sulfurization reaction is caused by dissolving hydrogen sulfide gas in the inside. By this sulfidation treatment, nickel and cobalt contained in the initial solution of the sulfidation reaction are immobilized as sulfide and recovered.
　なお、硫化反応の終了後においては、得られたニッケル及びコバルトの硫化物を含むスラリーをシックナー等の沈降分離装置に装入して沈降分離処理を施し、その硫化物のみをシックナーの底部より分離回収する。一方で、水溶液成分は、シックナーの上部からオーバーフローさせて貧液として回収する。 After the completion of the sulfidation reaction, the obtained slurry containing nickel and cobalt sulfides is charged into a sedimentation separator such as thickener and subjected to sedimentation treatment, and only the sulfides are separated from the bottom of the thickener. to recover. On the other hand, the aqueous solution component overflows from the top of the thickener and is recovered as a poor solution.
　以下に、本発明の実施例を示してより具体的に説明するが、本発明は、以下の実施例によって何ら限定されるものではない。 Examples of the present invention will be more specifically described below, but the present invention is not limited at all by the following examples.
　ここで、鉱石スラリー中の金属の含有率は、蛍光Ｘ線分析装置を用いて測定し、浸出処理により得られた浸出スラリー中の金属の含有率はＩＣＰ発光分析法により測定した。また、浸出スラリー中の遊離硫酸濃度は滴定法により測定した。また、ニッケルの浸出率については、［１００－（浸出スラリー中ニッケル品位÷鉱石スラリー中ニッケル品位）×１００（％）］として算出した。 Here, the metal content in the ore slurry was measured using a fluorescent X-ray analyzer, and the metal content in the leached slurry obtained by the leaching treatment was measured by ICP emission spectrometry. Also, the concentration of free sulfuric acid in the leached slurry was measured by a titration method. In addition, the leaching rate of nickel was calculated as [100− (nickel grade in leached slurry, nickel grade in nickel ore slurry ore slurry) × 100 (%)].
　［実施例１～３］
　ニッケル、コバルト、鉄、マグネシウム、亜鉛等を含む原料鉱石から鉱石スラリーを調製し、これをオートクレーブに装入した後、９８％硫酸を添加して高温加圧下で浸出処理を行った。この浸出処理においては、下記表２に示すように、浸出スラリー中のマグネシウム濃度を参照して、浸出スラリー中の遊離硫酸濃度が４０ｇ／Ｌ～５０ｇ／Ｌの範囲となるように硫酸添加量の調整を行った。 [Examples 1 to 3]
An ore slurry was prepared from a raw material ore containing nickel, cobalt, iron, magnesium, zinc and the like, and this was charged into an autoclave, and then 98% sulfuric acid was added to perform leaching treatment under high temperature pressure. In this leaching process, as shown in Table 2 below, with reference to the magnesium concentration in the leached slurry, the amount of added sulfuric acid is adjusted so that the free sulfuric acid concentration in the leached slurry is in the range of 40 g / L to 50 g / L. I made an adjustment.
　浸出処理条件は、以下の通りとした。
　・鉱石スラリーの固形分比率：４２重量％～４５重量％
　・鉱石スラリーのマグネシウム品位：０．８重量％～１．８重量％
　・浸出スラリーの流量：２００ｍ３／時～２５０ｍ３／時
　・高温加圧反応容器内の温度：２４０℃～２６０℃ The leaching conditions were as follows.
Solid content ratio of ore slurry: 42% by weight to 45% by weight
Magnesium grade of ore slurry: 0.8% by weight to 1.8% by weight
・ Flow rate of leaching slurry: 200 m 3 / hour to 250 m 3 / hour ・ Temperature in high temperature pressure reaction vessel: 240 ° C. to 260 ° C.
　［比較例１～３］
　鉱石スラリー中のマグネシウム品位を、蛍光Ｘ線分析装置を用いて測定し、その測定結果（鉱石スラリー中のマグネシウム品位）を参照して、浸出スラリー中の遊離硫酸濃度が４０ｇ／Ｌ～５０ｇ／Ｌの範囲となるように硫酸添加量の調整を行ったこと以外は、実施例と同様にして高温加圧浸出処理を行った。 [Comparative Examples 1 to 3]
The magnesium grade in the ore slurry is measured using a fluorescent X-ray analyzer, and the free sulfuric acid concentration in the leach slurry is 40 g / L to 50 g / L with reference to the measurement result (magnesium grade in the ore slurry). The high-temperature pressure leaching treatment was performed in the same manner as in the example except that the amount of added sulfuric acid was adjusted to be in the range of
　下記表２に、実施例及び比較例におけるニッケル浸出率と硫酸添加量を示す。なお、表２中の各数値は、定期的にサンプルを採取して測定した結果の一日の平均値である。 Table 2 below shows the nickel leaching rate and the amount of added sulfuric acid in Examples and Comparative Examples. In addition, each numerical value in Table 2 is the average value of the day of the result of having extract | collected the sample regularly and measured.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２の結果に示されるように、浸出処理により得られる浸出スラリー中のマグネシウム濃度に応じて硫酸添加量の調整を行った実施例１～３では、高いニッケル浸出率を維持しつつ、適正な硫酸添加量で処理を行うことができた。特に、鉱石スラリー中のマグネシウム品位が高い実施例３においても、ニッケルを高い浸出率で浸出させることができた。 As shown in the results of Table 2, in Examples 1 to 3 in which the amount of added sulfuric acid was adjusted according to the magnesium concentration in the leached slurry obtained by the leaching treatment, it was appropriate while maintaining a high nickel leaching rate. The treatment could be carried out with the amount of added sulfuric acid. In particular, also in Example 3 in which the magnesium grade in the ore slurry is high, it was possible to leach nickel at a high leaching rate.
　一方、鉱石スラリー中のマグネシウム品位に応じて硫酸添加量の調整を行った比較例１～２では、実施例と同様のニッケル浸出率を維持することができたものの、硫酸添加量は実施例に比べて多くなってしまい、余剰な硫酸が添加されたことが分かる。このことは、鉱石スラリー中のマグネシウム品位に応じて硫酸添加量の調整を行ったことにより、そのマグネシウム品位の測定に長時間を要してしまったため、正確に測定結果を反映させることができず、結果として実施例に比べて過剰な硫酸添加になってしまったことによると考えられる。また、比較例３では、実施例に比べてニッケル浸出率が低下してしまった。このことは、鉱石スラリー中のマグネシウム品位の測定に長時間を要してしまったことにより、正確に測定結果を反映させることができず、硫酸の添加量が結果として足らない状態となり、そのことがニッケル浸出率の低下につながったと考えられる。 On the other hand, in Comparative Examples 1 and 2 in which the addition amount of sulfuric acid was adjusted according to the magnesium grade in the ore slurry, although the same nickel leaching rate as in the example could be maintained, the addition amount of sulfuric acid It becomes more in comparison, and it can be seen that excess sulfuric acid is added. In this case, it took a long time to measure the magnesium grade by adjusting the amount of added sulfuric acid according to the grade of magnesium in the ore slurry, so the measurement results can not be accurately reflected. As a result, it is considered to be due to the fact that the sulfuric acid addition is excessive compared to the example. Moreover, in the comparative example 3, the nickel leaching rate fell compared with the Example. This takes a long time to measure the magnesium grade in the ore slurry, so that the measurement results can not be accurately reflected, and the addition amount of sulfuric acid results in an insufficient state, Is considered to have led to a decrease in the nickel leaching rate.

Claims (4)

  1. 　マグネシウムを含有するニッケル酸化鉱石のスラリー（鉱石スラリー）に対して硫酸を添加することによって浸出処理を施し、ニッケルを含む浸出液と浸出残渣とからなる浸出スラリーを得る浸出処理方法であって、
    　前記硫酸の添加量を、浸出処理により得られる浸出スラリー中のマグネシウム濃度に応じて、該浸出スラリー中の遊離硫酸濃度が所定の濃度となるように調整する
    　浸出処理方法。     A leaching method is carried out by subjecting a slurry of nickel oxide ore containing magnesium (ore slurry) to a leaching treatment by adding sulfuric acid to obtain a leaching slurry consisting of a leaching solution containing nickel and a leaching residue,
    A leaching treatment method, wherein the amount of the sulfuric acid added is adjusted so that the concentration of free sulfuric acid in the leached slurry becomes a predetermined concentration, according to the magnesium concentration in the leached slurry obtained by the leaching treatment.
  2. 　前記浸出スラリー中の遊離硫酸濃度が２５ｇ／Ｌ～５５ｇ／Ｌの範囲となるように、前記硫酸の添加量を調整する
    　請求項１に記載の浸出処理方法。     The leaching method according to claim 1, wherein the addition amount of the sulfuric acid is adjusted such that the concentration of free sulfuric acid in the leached slurry is in the range of 25 g / L to 55 g / L.
  3. 　前記浸出スラリー中のマグネシウム濃度を、ＩＣＰ発光分析法又は原子吸光分析法により測定する
    　請求項１又は２に記載の浸出処理方法。     The leaching method according to claim 1 or 2, wherein the magnesium concentration in the leached slurry is measured by ICP emission spectrometry or atomic absorption spectrometry.
  4. 　ニッケル酸化鉱石から硫酸を用いてニッケルを含む有価金属を回収するニッケル酸化鉱石の湿式製錬方法であって、
    　前記ニッケル酸化鉱石のスラリー（鉱石スラリー）に対して硫酸を添加することによって浸出処理を施し、ニッケルを含む浸出液と浸出残渣とからなる浸出スラリーを得る浸出工程を含み、
    　前記浸出工程では、前記硫酸の添加量を、前記浸出処理により得られる浸出スラリー中のマグネシウム濃度に応じて、該浸出スラリー中の遊離硫酸濃度が所定の濃度となるように調整する
    　ニッケル酸化鉱石の湿式製錬方法。     A wet smelting method of nickel oxide ore, wherein valuable metals including nickel are recovered from nickel oxide ore using sulfuric acid,
    Performing a leaching process by adding sulfuric acid to the slurry of the nickel oxide ore (ore slurry) to obtain a leaching slurry comprising a nickel-containing leachate and a leaching residue,
    In the leaching step, the addition amount of the sulfuric acid is adjusted according to the magnesium concentration in the leached slurry obtained by the leaching treatment so that the concentration of free sulfuric acid in the leached slurry becomes a predetermined concentration. Wet smelting method.
PCT/JP2018/037731 2017-11-08 2018-10-10 Leaching treatment method and hydrometallurgical method for nickel oxide ore WO2019093053A1 (en)

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