JP2000313928A - Method for recovering nickel and scandium from oxidized ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover useful Ni and Sc at high yield by leaching oxidized ore contg. Ni and Sc with acid, adding this leach liq. with a neutralizer, controlling the pH into specified ranges in plural stages and producing precipitates. SOLUTION: Ni-contg. oxidized ore is subjected to leaching treatment at high temp. under high pressure with sulfuric acid, hydrochloric acid, nitric acid or the like to obtain a treating soln. contg. iron, Al, Ni and Sc. This treating soln. is added with a neutralizer to control the pH to the range of 2 to 4, and iron and Al in the leach liq. are removed as precipitates. The liq. freed from iron and Al is added with a neutralizer to control the pH to the range of >4 to 7.5, and Sc in the soln. is recovered as precipitates. Moreover, it is added with a neutralizer to control the pH to >7.5, and Ni in the soln. is recovered as precipitates. As the neutralizers, alkali oxides such as the oxides, carbonates and hydroxides of Mg, Ca and Na are used. This method can be executed in such a manner that a combination of the 1st, 2nd and 3rd neutralizing stages is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for recovering nickel and scandium from an oxide ore containing nickel and scandium.

[0002]

2. Description of the Related Art Scandium is used as a high color rendering lamp in metal halide lamps used in gymnasiums and hotels, as an additive to single crystals for lasers as a solid laser oscillation source, and as a long afterglow orange for cathode ray tubes for displays. It is used for color phosphors, ferroelectric materials, piezoelectric materials and the like. In recent years, its use as a Lewis acid catalyst is also promising,
There is great hope for scandium compounds as new catalysts for the next generation.

On the other hand, scandium as a resource is contained in the earth's crust at about 5 to 10 ppm, but there is almost no ore that can be industrially used alone as a scandium source. Currently, industrially, the content is only a few pp
Refining residues of tin, titanium, tungsten, uranium, tantalum, niobium, bauxite, etc., of from m to several tens ppm are used as scandium-containing raw materials.

As a method of recovering scandium from such a raw material, conventionally, impurities other than scandium are removed by various methods such as solvent extraction, chelate extraction, and ion exchange after acid leaching of the scouring residue under atmospheric pressure. It is separated and recovered by removal. Such a scandium recovery method has the following problems. At the time of acid leaching, iron, aluminum, and the like, which are contained in large amounts other than scandium, are simultaneously leached at substantially the same ratio as scandium. For this reason, the concentration of iron or aluminum in the leachate is several hundred times higher than that of scandium, and the subsequent liquid treatment becomes complicated. For example, when iron or aluminum is removed as a hydroxide from an acid leaching solution, the hydroxide becomes a gel-like substance and is very difficult to remove. When iron or aluminum is removed from an acid leachate by solvent extraction, chelate extraction, or ion exchange, it is necessary to reduce the concentration of iron or aluminum. Wastewater treatment. If scandium is to be leached at a high rate, a large amount of acid is required because iron and aluminum, which are contained in large amounts other than scandium, are also leached at the same ratio as scandium.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a new method for recovering nickel and scandium. In particular, it is an object of the present invention to provide a novel method for recovering nickel and scandium from an oxide ore containing nickel and a trace amount of scandium at the same time.

[0006]

Means for Solving the Problems The present inventors have found that a small amount of a Clark number of 2 to 2 is contained in a nickel-containing oxide ore.
As a result of discovering that 20 times as much scandium was present and conducting various studies to efficiently recover this scandium, the acid leaching under high temperature and high pressure suppressed the leaching of iron and aluminum in the oxide ore. On the other hand, they found that almost all nickel and scandium were selectively and efficiently leached.

The acid leaching solution has a low content of impurities such as iron and aluminum, and it has been found that nickel and scandium can be recovered as a high-concentration precipitate only by adjusting the pH of the leaching solution. is there.

[0008] That is, the present invention is characterized in that scandium and nickel are recovered from a nickel-containing oxide ore by sequentially treating the nickel-containing oxide ore in the following steps (1) to (4). is there.

The gist of the invention is as follows: (1) a leaching step of leaching the oxide ore with an acid under a high temperature and a high pressure to obtain a leaching solution containing nickel and scandium; A) a neutralization step of adding iron and aluminum in the leachate as a precipitate by adding a neutralizing agent to the leachate to adjust the pH to a range of 2 to 4; A second neutralization step of adding a neutralizing agent to the solution after removing the precipitate in the summing step and adjusting the pH to a range of more than 4 to 7.5 to recover scandium in the solution as a precipitate; And (4) a third neutralization step of recovering nickel as a precipitate by adjusting the pH to more than 7.5 by further adding a neutralizing agent.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the present invention, nickel-containing oxide ore is used as a scandium recovery raw material. As mineral oxides containing nickel, laterite and garnierite are known mineralogically.
5 to 4.0%, 15 to 50% iron, 2 to aluminum
About 5%, and 0.0010 to 0.01
Contains 0% scandium.

In the present invention, first, such a nickel-containing oxide ore is leached with an acid in a leaching step.

In this leaching with an acid, in order to use the acid efficiently and to facilitate the processing step of the leachate in the subsequent step, scandium and nickel are preferentially dissolved from the oxide ore to oxidize. Iron and aluminum contained in the ore should be left as much as possible in the leach residue. As a result, the amount of acid used is reduced, and the leachate has a low iron and aluminum content, which facilitates post-treatment of the leachate.

For this reason, the leaching step is carried out at a high temperature and a high pressure using an autoclave. The temperature is 150-300 ° C,
The pressure is 5 to 60 kg / cm ² (gauge pressure, the same applies hereinafter),
Preferably, the temperature is 220-260 ° C and the pressure is 24-4.
It is carried out in a range of 8 kg / cm ² . If the temperature is lower than 150 ° C. and the pressure is lower than 5 kg / cm ² , the leaching rate of nickel and scandium decreases, and the iron and aluminum contents of the leaching solution may increase. When the temperature is higher than 300 ° C. and the pressure is higher than 60 kg / cm ² , the leaching speed of nickel and scandium increases, but the equipment and equipment become large and the cost increases, and the operating cost such as using extra energy is increased. Is also higher.

[0014] Such high temperature and high pressure are achieved by blowing pressurized steam into the autoclave. The injection of pressurized steam also has the effect of stirring the leachate, so that the leach reaction is promoted and the leach time is shortened. In addition, when stirring by an impeller is performed simultaneously in addition to the injection of pressurized steam, the leaching reaction can be completed within one hour.

The acid used in the leaching step can be any of sulfuric acid, hydrochloric acid and nitric acid. The amount of acid used is such that the pH of the leaching solution obtained by acid leaching under high temperature and high pressure is 0.5 to 0.5 at room temperature. It is preferable to adjust the value to 2. If the pH of the leaching solution is as low as less than 0.5, the content of iron and aluminum in the leaching solution increases, and a large amount of neutralizing agent is used for neutralization in a subsequent step, which is not preferable. On the other hand, if the pH of the leaching solution is a high value of 2 or more, the leaching rate of nickel and scandium decreases, which is not preferable.

When acid leaching is performed under the above conditions, 95% or more of nickel and scandium are leached, while the leaching rates of iron and aluminum are suppressed to 5% or less and 10% or less, respectively.

The leaching solution obtained from the leaching step thus obtained contains iron and aluminum in addition to nickel and scandium, and in the method of the present invention, the leachate is used as a first neutralization step. The pH is adjusted to between 2 and 4 by adding a wetting agent.

In the first neutralization step, iron and aluminum in the leachate are preferentially neutralized and precipitated, and nickel,
Separated from scandium. As the neutralizing agent, it is most convenient to use an alkali compound, but if it is available, an ore or the like containing an alkali compound can also be used. Alkali compounds include magnesium, calcium, sodium oxide, magnesium, calcium,
Sodium and ammonia carbonates or magnesium, calcium, sodium and ammonia hydroxides can be used. If the pH is less than 2, the neutralization precipitation of iron and aluminum is not complete, and if the pH is more than 4, nickel and scandium are also precipitated in addition to iron and aluminum. It is necessary to adjust the pH to the range of 2-4.

The precipitates of iron and aluminum thus formed in the first neutralization step are separated and removed by a known method such as filtration to obtain a first neutralized solution as a residual liquid.

[0020] The first neutralization solution obtained from the first neutralization step is free of iron and aluminum, and contains nickel and scandium. In the method of the present invention, the neutralization agent is then added to the first neutralization solution to adjust the pH to 4%.
A second neutralization step is performed, adjusting to a range of super-7.5.

In the second neutralization step, scandium in the first neutralization solution is preferentially neutralized, precipitated and separated from nickel. As the neutralizing agent, as in the case of the first neutralization step, magnesium, calcium, sodium oxide, magnesium, calcium, sodium, ammonium carbonate, or magnesium, calcium, sodium, ammonia hydroxide and the like Alkaline inclusions can be used. When the pH is less than 4, the neutralization precipitation of scandium is not complete, and when the pH is more than 7.5, precipitation of nickel in addition to scandium is also generated. It is necessary to adjust to a range of 7.5.

The precipitate of scandium generated in the second neutralization step as described above is separated and recovered by a known method such as filtration, and a second neutralized solution is obtained as a residual liquid. The concentrated precipitate of scandium recovered here is in the form of a hydroxide or carbonate of scandium, and the enrichment ratio of scandium to the hydroxide or carbonate of scandium depends on the original oxide ore. Scandium 4
It becomes 0 to 2000 times.

When the scandium concentrated precipitate obtained in the second neutralization step is used as a main raw material for purifying and recovering scandium, it can be easily dissolved in an acid, and can be used as an iron or aluminum alloy. And a high-concentration scandium-containing liquid containing few impurities is obtained. Therefore, it is possible to easily purify scandium by conventional solvent extraction, chelate extraction or ion exchange, and its technical and economic effects are great.

On the other hand, the second neutralization solution obtained from the second neutralization step is free of iron, aluminum and scandium, and contains nickel. In the method of the present invention, a third neutralization step is performed in which the neutralization agent is further added to the second neutralization solution to adjust the pH to more than 7.5.

In the third neutralization step, nickel in the second neutralization solution is neutralized and precipitated. As neutralizing agents, magnesium, calcium, sodium oxides, carbonates,
Alternatively, an alkali compound such as a hydroxide can be used. If the pH is 7.5 or less, the neutralization precipitation of nickel is not complete, so it is necessary to adjust the PH to more than 7.5 in the third neutralization step.

The nickel precipitate formed in the third neutralization step is separated by a known method such as filtration.
The solution is collected to obtain a third neutralized solution as a residual solution. The concentrated nickel precipitate recovered here is in the form of nickel hydroxide or carbonate, and the concentration ratio of nickel to the nickel hydroxide or carbonate is determined by the nickel oxide ore of the original oxide ore. 10 to 1000 times.

The third neutralization solution separated from the concentrated precipitate of nickel in the third neutralization step does not contain metals other than magnesium, calcium or sodium, especially heavy metals, and is discharged into a water body such as the ocean. However, since there is no problem in terms of pollution, it can be discharged as it is, or when an ammonia compound is used as a neutralizing agent in the first and second neutralization steps, it can be discharged after separating and recovering ammonia.

As described above, according to the present invention, useful nickel and scandium can be recovered from an oxide ore containing nickel and scandium by a relatively simple process.

The method of the present invention can also be used for the recovery of scandium from the refining residues such as tin, titanium, tungsten, uranium, tantalum, niobium, bauxite and the like.

In the method of the present invention, the combination of the first, second, and third neutralization steps is changed when there are economic reasons such as the components of the nickel-containing oxide ore and the omission of the production equipment. It is also possible to carry out.

For example, when the content of iron and aluminum in the nickel-containing oxide ore is low, nickel, scandium, iron and aluminum are simultaneously precipitated in one neutralization step without dividing the neutralization step. It is also possible to collect. In this case, an alkaline compound such as an oxide, carbonate, or hydroxide of magnesium, calcium, or sodium is used as a neutralizing agent, and the pH is 7.5.
Adjust to super.

For example, in order to make the nickel compound recovered from the nickel-containing oxide ore into a form suitable for the existing nickel recovery step, scandium, iron and aluminum coexist among the components contained in the nickel-containing oxide ore. It is possible to recover as a precipitate and nickel as a separate precipitate. In this case, PH first
Was adjusted to the range of 2 to 7.5 to precipitate scandium, iron and aluminum, and after separating the generated precipitate,
Next, the pH may be adjusted to more than 7.5 to precipitate nickel. In this case, nickel can be recovered not only by neutralization with a neutralizing agent but also by a known method such as sulfidation or hydrogen reduction.

Further, for example, when the nickel content in the nickel-containing oxide ore is low and the scandium content is high, scandium and nickel coexist after neutralizing and washing iron and aluminum with a neutralizing agent. It is also possible to collect as a precipitate. In this case, iron and aluminum are first precipitated by adjusting the pH to a range of 2 to 4, and then the pH is adjusted to more than 7.5 to simultaneously neutralize and precipitate nickel and scandium.

Further, the leachate itself is directly subjected to solvent extraction,
It can also be supplied to processes such as chelate extraction and ion exchange.

Hereinafter, specific embodiments of the present invention will be described. It should be noted that, in the examples, when “%” is indicated, all are% by weight (Wt%).

[0036]

Example 1 Garnierite ore (Ni: 1.6%, S
c: 0.003%, Fe: 30.5%, Al: 2.0
%) To a slurry concentration of 25% with water, 240 g of 98% sulfuric acid was added to 1 kg of ore, and the autoclave was leached at a temperature of 240 ° C. and a pressure of 35 kg / cm ² for 1 hour, and then the pressure of the autoclave was reduced to atmospheric pressure.

The pH of this leachate at room temperature is 0.95,
Ni: 7.9 g / l, Sc: 0.015 g / l, Fe:
A leachate having a concentration of 1.3 g / l and Al: 0.3 g / l was obtained. At this time, the leaching rates of Ni and Sc were both 95%, and the leaching rates of Fe and Al were suppressed to 0.8% and 3.0%. The leaching rate is a percentage of the weight of leached Ni and Sc with respect to the weight of Ni and Sc contained in the ore. The same applies to the leaching rates of Fe and Al.

Calcium carbonate is added to this leachate to adjust the pH.
Was set to 3.5, and Fe and Al were precipitated and removed as carbonates. At this time, the precipitation and removal rates of Fe and Al were 95%, respectively.
And 87%. The precipitation rate of Sc is 5%, and N
That of i was 0.3%. The precipitation removal rate is based on the weight of Fe and Al contained in the leachate.
Percentage by weight of Fe and Al precipitated out.

Next, sodium carbonate was added to the solution from which Fe and Al had been removed by precipitation to adjust the pH to 5.8, and the precipitate was recovered as Sc as a carbonate. The precipitation recovery rate of Sc at this time was 98%. The precipitation rate of Ni was 2.8%.
The precipitation recovery rate of Sc is the percentage of the weight of Sc recovered and precipitated with respect to the weight of Sc contained in the leachate, and the precipitation rate of Ni is the percentage of Ni contained in the leachate. Is the percentage of the weight of Ni precipitated based on the weight of

The component of this carbonate is Ni: 29.3%,
Sc: 1.86%, Fe: 8.6%, Al: 5.2%
And Sc is 62% of Sc of the original garnierite ore.
It was concentrated 0-fold.

Further, magnesium oxide was added as a neutralizing agent to the solution after Sc was recovered as a carbonate to adjust the pH to 8.0, and Ni was recovered as a hydroxide. At this time, the recovery rate of Ni into the precipitate was 100%, and a hydroxide of Ni: 45.3% was obtained as a precipitate. Ni was enriched 28 times with respect to the original garnierite ore. As described above, in the present embodiment, since Fe and Al contained in the leachate are first precipitated and removed, Sc obtained by the subsequent processing is removed.
And Ni precipitates are effective in obtaining high purity.

[0042]

Example 2 Laterite ore (Ni: 1.1%, Sc:
(0.005%, Fe: 45.2%, Al: 2.8%) to a 30% slurry concentration with water, and 98% sulfuric acid to ore 1
145 g per kg, and the temperature was adjusted to 2 by autoclave.
After leaching at 40 ° C. and a pressure of 35 kg / cm ² for 1 hour, the pressure of the autoclave was reduced to atmospheric pressure.

The pH of this leachate at room temperature is 1.02,
Ni: 5.4 g / l, Sc: 0.025 g / l, Fe:
A leachate having a concentration of 1.2 g / l, Al: 0.4 g / l was obtained. At this time, the leaching rates of Ni and Sc were both 95%, and the leaching rates of Fe and Al were suppressed to 0.5% and 2.8%.

Ammonia water was added to the leachate as a neutralizing agent to adjust the pH to 5.5, and Sc, Fe and Al were precipitated and separated as hydroxides and collected. Sc, F at this time
e and Al precipitation recovery rates are 98% and 100%, respectively.
And 100%. The precipitation rate of Ni was 0%. The component of this hydroxide is Sc: 0.67%, F:
e: 32.2%, Al: 10.7%. Sc was 134 times the Sc of the original laterite ore.

To the solution after recovering Sc, Fe and Al as hydroxides, sodium hydroxide was added to adjust the pH to 8.2, and Ni was precipitated as hydroxides. The precipitation recovery rate of Ni at this time was 100%, and a hydroxide of Ni: 48.6% was obtained. Ni was 44 times that of the original laterite ore. In this embodiment, Sc, Fe, and Al contained in the leachate are first precipitated and recovered as hydroxides. Since only Ni needs to be recovered in the subsequent steps, processing equipment and processing steps can be omitted. effective.

[0046]

Example 3 The pH of the leachate obtained in Example 2 was adjusted to 7.8 by adding sodium carbonate as a neutralizing agent to Ni, Sc, F
All of e and Al were precipitated and separated and recovered as carbonate.

The component of this carbonate is Ni: 32.3%,
Sc: 0.15%, Fe: 7.2%, Al: 2.4%
Thus, Ni and Sc were both enriched 30 times with respect to the original laterite ore, Ni and Sc. This actual rotation example is a method in which Sc, Fe, Al, and Ni contained in the leachate are all precipitated and recovered as hydroxides, and the processing equipment and processing steps are further omitted as compared with Example 2. There is an effect that can be done.

[0048]

As described above, the present invention provides a method for recovering useful nickel and scandium in high yield from oxide ores containing nickel and scandium by relatively simple technical means. The technical and economic effects are extremely large.

Claims (1)

[Claims] 1. A method for recovering nickel and scandium from an oxide ore containing nickel and scandium, comprising: (1) a leaching step of leaching the oxide ore with an acid under a high temperature and a high pressure to obtain a leachate containing nickel and scandium;
(2) a first neutralization step in which iron and aluminum in the leachate are removed as precipitates by adding a neutralizing agent to the leachate to adjust the pH to a range of 2 to 4; A second neutralization step of adding a neutralizing agent to the solution after removing the precipitate in the step and adjusting the pH to a range from more than 4 to 7.5 to recover scandium in the solution as a precipitate,
(4) a third neutralization step of recovering nickel in the solution as a precipitate by further adjusting the pH to more than 7.5 by adding a neutralizing agent; And how to recover scandium.