JP2003073750A - Method for leaching sulfide ore containing copper pyrite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for leaching a sulfide ore containing copper pyrite, in which the sulfide ore containing copper pyrite is chemically leached in versatile conditions in a practical operation level. SOLUTION: The method for leaching the sulfide ore containing copper pyrite by using sulfuric acid, comprises measuring a period for a potential of the pulp to reach 400 mV when measured with a saturated calomel electrode, and a leaching rate of copper, beforehand, charging a raw material containing a copper quantity leachable by the time when the electric potential calculated from the period and the leaching rate reaches 400 mV, and leaching it.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for chemically leaching a sulfide ore containing chalcopyrite which is a mineral that becomes a major copper ore.

[0002]

2. Description of the Related Art In the case of obtaining copper (Cu) from an ore, the hydrometallurgical method requires less equipment investment and can be operated flexibly in comparison with the conventional dry metallurgical method, and the copper ingot can be directly produced at the mountainside. There are advantages such as copper oxide ore and secondary copper sulfide ore are applied, and as a method of sulfuric acid leaching, for example, chemical leaching performed by adjusting the ore grain size and temperature under sulfuric acid acidity, and iron oxidizing bacteria at room temperature Leaching with bacteria.

However, sulfide ores containing chalcopyrite, which is widely used as a resource of copper, is known as a mineral that is difficult to leach with sulfuric acid, and it does not leach unless it is harsh conditions such as high temperature, strong acid, and high pressure. Various studies have been made.

For example, US Pat. No. 5,730,776 proposes a technique of adding carbonaceous matter such as coal as a reaction accelerator. However, the leaching reaction temperature is 90 to 2
There is a problem that the conditions are severe at 20 ° C. and pressure of 100 to 3000 kPa.

For example, US Pat. No. 4,343,773 proposes a technique of adding carbon such as graphite in order to increase the electric conductivity of a solution, and US Pat.
21, US Pat. No. 6,159,435, JP 2000-
In 515585 and the like, a method of leaching copper by recycling trivalent iron and continuously adding it has been proposed.

[0006]

However, in the above-mentioned technique, when the concentration of trivalent iron is increased, there is a problem that the leaching rate of copper is remarkably decreased on the way and the leaching is not maintained until the end.

Further, chalcopyrite in the Kuroko type complex sulfide ore is
Beneficiation is difficult and there are many cases in which high-quality copper concentrate cannot be obtained. Such concentrate cannot be used as a raw material for dry refining, and development of hydrometallurgy using these as raw materials is expected.

In view of such circumstances, it is an object of the present invention to provide a method for leaching a sulfide ore containing chalcopyrite which chemically leaches a sulfide ore containing chalcopyrite under practical and versatile conditions. .

[0009]

A first aspect of the present invention for solving the above-mentioned problems is a method of leaching sulfide ore containing chalcopyrite with sulfuric acid, which is a potential of pulp measured with a saturated calomel electrode. Is measured in advance and the leaching rate of copper is measured, and leaching is performed by charging a raw material in an amount of copper that can be leached until the potential calculated from the period and the leaching rate becomes 400 mV. It is a method of leaching sulfide ores containing chalcopyrite.

In the first aspect, the leaching reaction proceeds rapidly and continuously without lowering to the end, and the copper material does not remain.

A second aspect of the present invention is the method for leaching sulfide ore containing chalcopyrite, which is characterized in that, in the first aspect, sulfide ore coexisting with pyrite is used.

In the second aspect, the copper leaching reaction is promoted by the galvanic effect of chalcopyrite and pyrite.

A third aspect of the present invention is the method for leaching sulfide ore containing chalcopyrite, characterized in that the sulfide ore having a copper grade of 5 to 10% is used in the first or second aspect.

The third aspect can be applied to complex sulfide ores that are difficult to be processed.

A fourth aspect of the present invention is a leaching method for sulfide ore containing chalcopyrite, which is characterized in that leaching is performed at 45 ° C. to 55 ° C. in any one of the first to third aspects.

In the fourth aspect, the leaching reaction is maintained quickly and completely at a relatively low temperature.

According to the present invention, copper can be leached at 1000 mg / L / day or more even if a concentrate having a copper grade of 5 to 10% is used, and the leaching does not stop midway, and the raw material is wasted. Can be leached to the end without having to.

The structure of the present invention will be described in more detail below.

The present invention relates to chalcopyrite (chemical formula: CuFe
When the sulfide ore containing S ₂ ) is leached with sulfuric acid, the reactions represented by the following reaction formulas (1) to (3) occur, and (1) to (3)
It is based on the knowledge that when the reaction of (3) progresses in a well-balanced manner, the copper leaching rate becomes faster and the leaching proceeds continuously.

That is, in the leaching of chalcopyrite, Fe ³⁺ in the leachate acts on the chalcopyrite as an oxidizing agent, and Cu is leached according to the reaction formula (1).

Fe as an oxidizer in the formula (1)
³⁺ is supplied by oxidizing Fe ²⁺ by aeration represented by the reaction formula (2).

Further, S ^{0 and the} like produced by the Cu leaching reaction of the formula (1) are oxidized by the reaction formula of the (3), for example.

[0023]

Embedded image CuFeS ₂ + 4Fe ³⁺ → Cu ²⁺ + 5Fe ²⁺ + 2S ⁰ (1)

[0024]

Embedded image Fe ²⁺ + 1 / 2O ₂ + 2H ⁺ → Fe ³⁺ + H ₂ O (2)

[0025]

Embedded image S ⁰ + 3 / 2O ₂ + H ₂ O → H ₂ SO ₄ (3)

Here, in order to proceed the reactions shown in (1) to (3) in a well-balanced manner, the pulp potential measured by a saturated calomel electrode (hereinafter referred to as "oxidation-reduction potential").
It was found that it is preferable to maintain the reaction so that the voltage does not exceed 400 mV. That is, it was found that if Fe ³⁺ is added too much, the oxidation-reduction potential exceeds 400 mV, and the copper leaching rate is significantly reduced.

As the copper leaching reaction of the above (1) to (3) progresses, the redox potential increases, but the redox potential and the copper leaching amount are as shown in FIG.
The amount of copper leaching becomes maximum when it is about 0 to 400 mV.

When the redox potential is higher than 400 mV, the reaction of the above formula (1) proceeds rapidly, but the amount of reaction products such as S ⁰ also increases and the surface of chalcopyrite is covered with the reaction products such as S ⁰ . It is considered that the reaction of the equation (1) becomes slow and the amount of Cu leached out becomes small.

If the leaching solution contains too much Fe ^{3+ as the} oxidant, the reaction of the formula (1) will proceed rapidly and the surface of the chalcopyrite will be covered with the reaction product, so that Cu will not be leached easily.
Since the oxidation reaction of sulfur with oxygen is slower than the reactions of the equations (1) and (2), the coated sulfur is not dissolved.

Therefore, in the present invention, the redox potential is 40%.
By the time of reaching 0 mV, a leaching copper raw material is charged and copper leaching is performed. As a result, the copper leaching rate is maintained at a high level, and the copper does not remain when the copper leaching rate decreases, and the next preparation can be performed without waste.

Although such preparation differs depending on the leaching equipment, the copper concentration in the leaching solution after the leaching is 4 to 6 g /
The copper grade and pulp concentration of the flotation concentrate may be adjusted so as to be about L.

As described above, when the raw material of copper that can be leached is charged before the redox potential reaches 400 mV, the leaching of copper can be effectively performed. In the leaching method of the present invention, other conditions are not particularly limited.

In the present invention, it is preferable that the leaching is carried out in the presence of pyrite. Generally, copper is concentrated so that pyrite does not coexist, but it is difficult to remove the pyrite. However, in the present invention, it has been found that the coexistence of pyrite improves the leaching rate.

As described above, the higher the content of pyrite (hereinafter referred to as "iron grade"), the higher the copper leaching rate is because the natural potential of pyrite is higher than that of chalcopyrite. Moreover, it is thought that the galvanic effect promotes the leaching of copper.

That is, since the leaching rate of copper becomes faster as the iron quality becomes higher due to the influence of the electric potential, it is preferable to leach in the state where pyrite coexists without purposely selecting. Therefore, in the present invention, copper can be leached at 1000 mg / L / day or more even for complex sulfide ore having a copper grade of about 5 to 10%.

On the other hand, it is preferable that the amount of sphalerite is not more than that of chalcopyrite. That is, sphalerite is leached preferentially to chalcopyrite and digests Fe ³⁺ and sulfuric acid in the solution to inhibit and delay leaching of chalcopyrite. However, if the Zn quality is lower than the Cu quality, there is no effect, so
It is preferable to use one having a Zn quality lower than that of Cu.

In the present invention, similarly to general chemical leaching, copper is leached by adding sulfuric acid and performing aeration while heating. It is generally said that the higher the temperature, the higher the leaching rate, but in the present invention, the leaching temperature is preferably 45 ° C to 55 ° C. It is presumed that this is because if the temperature is too high, the reaction of the above formula (1) proceeds too fast and is affected by the coating of sulfur or the like, so that the leaching rate becomes slow. Therefore, in the present invention, it is preferable that the leaching is performed at 45 ° C to 55 ° C, particularly around 50 ° C.

In the present invention, the sulfuric acid concentration is 0.2 to 0.6 N.
And it is particularly preferable to set it to about 0.3 to 0.4N. With a sulfuric acid concentration of this level, for example, a concentrate having a relatively coarse grain size of 80% pass size (hereinafter referred to as P ₈₀ ) of 20 to 30 μm can be leached at a sufficient rate, and if the concentration is higher than this. This is because there is no difference in terms of leaching speed. In addition, if a concentrate of P ₈₀ = 20 to 30 μm can be used as a raw material, a general-purpose crusher such as a ball mill can be used, and there is an advantage that it is not necessary to pulverize P ₈₀ = 20 μm or less. Further, if the sulfuric acid concentration is made higher than necessary, it is not preferable in that the acid resistance of the equipment tends to cause a problem.

An example of hydrometallurgy to which the leaching method of the present invention can be applied is shown in FIG.

As shown in FIG. 2, first, an ore 1 such as a beneficiated slag or a low-grade ore is crushed if necessary (step S1), crushed (step S2), and then floated (step S3). As a result, the waste 2 and the froth 3 are separated. Next, after re-milling the floss 3 (step S4),
After performing the leaching of the present invention (step S5), the leaching solution is filtered (step S6) to separate the filtrate 4 and the residue 5. Next, the filtrate 4 is solvent-extracted (step S7), stripped (step S8), and electrolytically collected (step S9) to obtain electrolytic copper 6. A part of the raffinate 7 of the solvent extraction (step S7) is returned to the leaching step (step S5), the rest is oxidized by bacteria (step S10), and then the pH is adjusted to about pH 4 (step S11) and filtered. By (step S12), the iron cake 8 is obtained. This filtration (step S12)
The pH of the filtrate 9 is adjusted again to about pH 10 (step S
13) and filter (step S14). The residue is the zinc cake 10 which is a solid deposit, and the filtrate 11 is neutralized by the pH adjustment (step S15) to form the waste liquid 12.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to Examples.

(Example 1) The ore used for leaching is a sulfide ore concentrate containing chalcopyrite obtained by flotation of a beneficiated slag of the Jezkent mine, Republic of Kazakhstan. Quality is Cu 3%, Z
The copper content in the concentrate is almost in the form of chalcopyrite. This concentrate was crushed with a ball mill and used with a particle size of P ₈₀ = 10 μm.

50 g of ore was added to 500 mL of 0.2 N sulfuric acid, and aeration was carried out at a rate of 0.5 L / min. The leaching temperature is 30 ° C, 40 ° C, 50 ° C, 60
℃ and 70 ℃. The measurement results of the amount of copper leached for one day, two days, and three days are shown in FIG.

As a result, at 30 to 50 ° C., the amount of copper leaching increased as the temperature increased, but when it exceeded 50 ° C., the increase stopped and the amount of leaching decreased rather. From this, it was found that the leaching temperature is preferably around 50 ° C.

(Example 2) The ore used for leaching is the same as in Example 1.
It is a sulfide concentrate containing chalcopyrite obtained in the same manner as in. This concentrate was crushed with a ball mill in the same manner as in Example 1 to have a particle size of P ₈₀ = 10 μm.

Initial density is 0.2N, 0.4N, 0.6N
50 g of ore was added to 500 mL of the sulfuric acid changed to, and leaching was performed at a temperature of 50 ° C. Aeration is 0.5L /
It was performed at a speed of min. FIG. 4 shows the measurement results of the amount of copper leaching for one day, two days, and three days at this time.

Up to an initial sulfuric acid concentration of 0.4 N, the higher the sulfuric acid concentration, the greater the amount of copper leaching.
It was found that the amount of copper leaching did not change even when the sulfuric acid concentration increased. (Example 3) The ore used for leaching is a sulfide ore concentrate containing chalcopyrite obtained by flotation of a beneficiated slag of the Jezkent mine, Republic of Kazakhstan. Quality is Cu2%, Zn2%, Fe
40%, and the copper in the concentrate is almost in the form of chalcopyrite. This concentrate was ground by a ball mill while changing the time for grinding, and the particle size was adjusted to three levels of P ₈₀ = 10, 20, 30 μm.

50 g of ore of each particle size was added to 500 mL of sulfuric acid, and aeration was carried out at a temperature of 50 ° C. to 0.5 L / mi.
The leaching was performed at a rate of n. The sulfuric acid concentration was 0.3N and 0.4N, respectively. FIG. 5 shows the measurement results of the amount of copper leached for 1 day, 2 days, and 3 days at this time.

It was found that the finer the grain size, the faster the copper leaching rate, but increasing the sulfuric acid concentration from 0.3N to 0.4N has a smaller effect on the copper leaching rate. Therefore, it was found that when the sulfuric acid concentration was 0.4 N, the one having a relatively coarse particle size could be used.

(Example 4) A sulfide ore concentrate containing chalcopyrite, pyrite concentrate, and quartz were mixed, and copper ore having a copper grade of about 4% and iron grades of 6%, 23%, and 36%, respectively, was used. Was leached.

50 mL of each ore in 500 mL of 0.2N sulfuric acid
Leaching was performed, and leaching was performed at a temperature of 50 ° C. while performing aeration at a rate of 0.5 L / min. The measurement result of the copper leaching amount is shown in FIG.

As a result, it was found that the copper leaching rate became higher as the iron quality became higher.

As described above, in the sulfide ore containing chalcopyrite, the presence of pyrite rather has an effect of promoting the leaching of copper, so it was found that copper can be leached without beneficiation to improve the copper grade.

(Example 5) The ore used for leaching is a sulfide ore concentrate containing chalcopyrite obtained by flotation of a beneficiated slag of the Jezkent mine, Republic of Kazakhstan. Quality is Cu2%, Z
n2% and Fe39%, and the copper in the concentrate is almost in the form of chalcopyrite. The concentrate was crushed with a ball mill and the particle size was adjusted to P ₈₀ = 30 μm.

The amount of ore leached is 50 g, 100 g, 15
Leaching was performed by changing the amount to 0 g and adding to 500 mL of 0.3 N sulfuric acid. These have a pulp concentration PD of 10%, 20%, and 30%, respectively. Leaching temperature 50 ° C
And leaching was performed while performing aeration at a rate of 0.5 L / min. The measurement result is shown in FIG. 7.

The higher the pulp concentration, the higher the copper leaching rate, but it was found that the leaching efficiency was poor at 30% because the leaching rate did not change so much between 20% and 30%.

(Example 6) The ore used for leaching is a sulfide ore concentrate containing chalcopyrite obtained by flotation of a beneficiated slag of the Jezkent mine, Republic of Kazakhstan. Grade is Cu 5%, Z
n4%, Fe39%, and copper in the concentrate is present in the form of chalcopyrite. This concentrate is re-ground with a ball mill,
The particles having a particle size of P ₈₀ = 25 μm were used.

Approximately 4 m of 0.4 N sulfuric acid was added to a 5 m ³ leaching tank.
³ and about 430 kg of ore were added, and leaching was performed at a temperature of 50 ° C. The impeller was stirred at 70 rpm and the circulation pump was operated to prevent the ore from stagnation in the spigot pipe. The aeration is 2.2m ^{3 with a} blower.
It was blown into the leaching tank at a flow rate of / min. The results are shown in FIG.

5 g / L of Cu was leached within 5 days from the start of leaching. The leaching reaction appears to be nearly complete in 4 days. Looking at the change in redox potential, it was in the range of 380 to 400 mV until about the third day, and 1 g / L per day.
The above copper leaching amount was shown, and the redox potential was 42% on the 4th day.
The leaching was completed when the voltage exceeded 0 mV.

Therefore, it was found that in this plant, it is preferable to charge the raw material in the amount of copper that completes the leaching in 3 days.

[0061]

As described above, in the method of chemically leaching sulfide ore containing chalcopyrite with sulfuric acid, the redox potential suitable for copper leaching is adjusted by adjusting the amount of copper in the raw material and the temperature. By maintaining the rate, the leaching rate of copper can be increased, so that there is an effect that leaching can be performed under mild conditions with respect to temperature, acidity, and pressure. Also, the leaching rate of copper is faster as the amount of pyrite is higher due to the effect of the natural potential, so
It is preferable to leach in the state where pyrite coexists without purposely selecting, and it is also applicable to complex sulfide ore.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a redox potential and a copper leaching amount.

FIG. 2 is a diagram showing an example of hydrometallurgy to which the leaching method of the present invention can be applied.

FIG. 3 is a diagram showing a result of Example 1.

FIG. 4 is a diagram showing the results of Example 2.

5 is a diagram showing the results of Example 3. FIG.

FIG. 6 is a diagram showing the results of Example 4.

FIG. 7 is a diagram showing the results of Example 5.

FIG. 8 is a diagram showing the results of Example 6.

Claims (4)

[Claims] 1. A method of leaching sulfide ore containing chalcopyrite using sulfuric acid, wherein the period until the pulp potential measured with a saturated calomel electrode reaches 400 mV and the leaching rate of copper are measured in advance, and A method for leaching a sulfide ore containing chalcopyrite, characterized in that a leaching is performed by charging a raw material in an amount of copper that can be leached until the electric potential calculated from the period and the leaching rate reaches 400 mV. 2. The method for leaching sulfide ore containing chalcopyrite according to claim 1, wherein sulfide ore coexisting with pyrite is used. 3. The copper grade according to claim 1 or 2,
A method for leaching sulfide ore containing chalcopyrite, which comprises using 10% of sulfide ore. 4. The method according to claim 1, wherein the temperature is 45 ° C.
A method for leaching a sulfide ore containing chalcopyrite, which comprises leaching at 55 ° C.