JPH09263408A - Separation of arsenic from arsenic sulfide-containing smelting intermediate product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient and inexpensive method for sepn. of arsenic from an arsenic sulfide-contg. smelting intermediate product. SOLUTION: An oxidation leaching stage is executed in the presence of copper sulfide at the time of subjecting the arsenic sulfide-contg. smelting intermediate product to the oxidation leaching stage preferably while blowing air in the presence of an alkali (more preferably sodium hydroxide) and separating arsenic as arsenate. The copper sulfide may be derived from the arsenic sulfide- contg. smelting intermediate product or may be added thereof or may be the combination thereof. Then, the copper sulfide obtd. by subjecting the soot ashes included in the waste gases emitted when copper sulfide ore is subjected to matte smelting and converter smelting in, for example, copper smelting and the waste electrolytic liquid contg. the copper and arsenic obtd. by further subjecting the electrolytic tailing liquid to a decopperizing electrolysis stage after obtaining electric copper by electrolytic drawing to a sulfidation treatment by using water sulfide (NaSH) is the object to be treated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an improved method of separating arsenic from arsenic sulfide-containing smelting intermediates produced during non-ferrous smelting processes. More specifically, the present invention provides an arsenic sulfide-containing smelting process in which an arsenic sulfide-containing smelting intermediate produced in a non-ferrous smelting process is subjected to an oxidative leaching step in the presence of an alkali to separate arsenic as an arsenate. It relates to an improved method of separating arsenic from intermediates.

[0002]

2. Description of the Related Art Various smelting intermediates such as soot and slag are generated in the non-ferrous smelting process regardless of dry type or wet type. These smelting intermediates are called copper, zinc, bismuth and antimony. It contains valuable resources and is usually recovered and recycled to the smelting process repeatedly from an economic point of view. In this case, if arsenic is not separated, it will be concentrated and accumulated in the smelting intermediate.
Required to be removed. However, when the smelting intermediate contains arsenic in the sulfide form together with the valuables, such as the waste acid sulfide produced when processing sulfide ores accompanied by arsenic sulfide, it is not possible to separate only arsenic. It was technically difficult for a long time.

Recently, a technically feasible method has been proposed. One of the methods is one in which a smelting intermediate is baked by oxidation, and arsenic is volatilized as arsenous acid and condensed. There is a method of separating and collecting as fine powdery arsenous acid. Although this method has already been put to practical use, it is relatively simple, but on the other hand, there is a problem that a large-scale facility is required to prevent the diffusion of arsenic into the atmosphere.

Another method utilizing the leaching method is JP-A-54.
No. 160590, the alkali metal is added to the sulfide-containing smelting intermediate containing arsenic while the air is blown into the smelting intermediate to adjust the pH to 5 to 8, and leaching is performed to adjust the arsenic to acidic arsenic. It is characterized in that it is separated as an acid salt, unlike the method described above, it does not require a large-scale air pollution control equipment, on the other hand, because the leaching rate of arsenic is extremely slow, it requires a large reactor, Has a problem that it consumes a large amount of energy such as steam for heating.

Therefore, a method generally used for separating arsenic from various aqueous solutions containing arsenic and copper generated in the electrolytic refining process of copper is first to recover copper in the form of sulfide by a sulfurization method. The arsenic is then removed by the sulfurization method. As can be easily understood, this method requires a solid-liquid separation step for copper sulfide and a solid-liquid separation step for arsenic-containing sulfide, and the two solid-liquid separation steps increase the processing cost. It has become.

[0006]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an efficient and inexpensive method for separating arsenic from arsenic sulfide-containing smelting intermediates.

The present invention also provides an arsenic sulfide-containing smelting intermediate which is subjected to an oxidative leaching step in the presence of an alkali to separate arsenic as an arsenate. The aim is to provide an improved separation method.

[0008]

The inventor of the present invention is based on the finding that leaching can be promoted by utilizing the catalytic action of a metal having a plurality of valences such as copper in an oxidation reaction such as air oxidation. From this aspect, the above-mentioned JP-A-54-160590.
An attempt was made to improve the leaching method proposed in the publication. The improvement plan of the above method, which is expected to catalyze the copper, inevitably raises the pH of the slurry because the arsenic is leached through the alkali in order to efficiently separate only the arsenic content.
As a result, the above-mentioned metals are also precipitated, and as a result, it was considered impossible to realize the expected catalytic action, and it was considered unrealizable. In the method for separating arsenic from an arsenic sulfide-containing smelting intermediate in which the smelting intermediate is subjected to an oxidative leaching step in the presence of an alkali to separate arsenic as an arsenate,
Surprisingly, the presence of copper in the form of copper sulfide in the oxidative leaching process successfully demonstrated the catalytic function of copper, resulting in a significant increase in the leaching rate of arsenic into the leachate. Further, they found that the leaching rate also increased at the same time, and completed the present invention. That is, the present invention, in the method for separating arsenic from an arsenic sulfide-containing smelting intermediate which is subjected to an oxidative leaching step in the presence of an alkali, an arsenic sulfide-containing smelting intermediate to separate arsenic as an arsenate. The oxidation leaching step is performed in the presence of copper sulfide.

In the present invention, the copper sulfide may be derived from or added to an arsenic sulfide-containing smelting intermediate,
A combination thereof may be used. The alkali used in the leaching step is added to adjust the pH, and in principle, any alkali can be used, but it is necessary to form an insoluble salt of leached arsenic such as calcium hydroxide. Alkali is unsuitable. The preferred alkali is sodium hydroxide.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments of the present invention will be described in detail.

The present invention relates to a method for separating arsenic from an arsenic sulfide-containing smelting intermediate in which an arsenic sulfide-containing smelting intermediate is subjected to an oxidative leaching step in the presence of an alkali to separate arsenic as an arsenate. The oxidation leaching step is performed in the presence of copper sulfide. Smelting intermediates include soot, residual syrup, furnace liquid, overflow, which occur in a series of smelting processes such as dry smelting, hydrometallurgy, dry refining, and wet refining.
In the present invention, a smelting intermediate containing arsenic in the form of a sulfide is used as an object of treatment, although an electrolytic tail solution and the like are included. Arsenic is widely associated with metal sulfide minerals, and is often contained in the form of sulfide in soot ash when sulfide ore associated with arsenic sulfide is processed. In some cases, it may be contained in the form of sulfide in the furnace liquid and the overflow, and these are also subject to the treatment of the present invention. Further, those obtained by subjecting arsenic to a sulfide form by subjecting these to a pretreatment and adding, for example, sodium hydrosulfide (NaSH) are also included in the smelting intermediate to be treated in the present invention.

The alkali is used for pH adjustment as described above, and sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like can be used, but sodium hydroxide is preferable. The pH is preferably adjusted to 6-9. More preferably 6.5-
Adjust to 7.5. Even if the pH exceeds 9, the arsenic leaching rate is not adversely affected, but the oxidation rate of the sulfur content in the smelting intermediate becomes high, and as a result, sulfuric acid is produced,
It becomes necessary to add an alkali to neutralize sulfuric acid. If the pH is less than 6, not only the leaching rate of arsenic will decrease, but also other coexisting valuables will leach out to a considerable extent. Therefore, the above range was determined from a practical viewpoint.

The copper sulfide may be derived from the smelting intermediate containing arsenic sulfide or may be added. Here, "derived from arsenic sulfide-containing smelting intermediate" means that copper sulfide is contained in the arsenic sulfide-containing smelting intermediate, and "added" means arsenic sulfide-containing smelting intermediate. It means that copper sulfide is added from other than the wrought intermediate. In the method of the present invention, a combination of both may be used. Typical examples included in the former are, in copper smelting, soot ash contained in exhaust gas emitted when copper sulfide ore is subjected to mat smelting or converter smelting, and after obtaining electrolytic copper by electrolytic extraction. In some cases, the electrolytic tail solution obtained by subjecting the electrolytic tail solution to a copper removal electrolysis step is subjected to sulfurization treatment using sodium hydrosulfide (NaSH). As an example of the latter, for example, leaching by oxidation (usually air oxidation) in the presence of an alkali as in the present invention, and addition of residual rhodium containing copper sulfide after separating arsenic by solid-liquid separation is added. There are cases. The amount of copper sulfide is determined in relation to the amount of arsenic contained in the smelting intermediate. Preferably, the Cu / As molar ratio is 0.1 to 0.
Adjust to become 5. Although it can be adjusted to exceed 0.5, the amount of copper contained in the residual leachate increases correspondingly.

In order to carry out the oxidative leaching step, it is necessary to add an oxidant to the arsenic sulfide-containing smelting intermediate, and usually air is used as the oxidant and this is sprayed. Needless to say, pure oxygen gas, oxygen-containing gas other than air, etc. can be used. In the method of the present invention, when air is used, the blowing amount is
Considering the leaching rate and the leaching rate and the economical efficiency, preferably 0.5 to 1.5 m ³ / l of leaching solvent
Although it is a minute, it is also possible to set beyond this range. Compared with the case where copper sulfide is not used, in the case of the method of the present invention, the amount of air blown can be significantly reduced, and as a result, the reaction equipment can be advantageously downsized.

Water is usually used as the leachate, but an aqueous solution prepared by dissolving the above-mentioned alkali may be used. The temperature of the leachate is preferably 50-90 ° C. This is because the reaction easily shifts to the right.

According to the method of the present invention, the following reactions are typically expected to proceed when sodium hydroxide (NaOH) is used: As ₂ S ₃ + 3 / 2O ₂ + H ₂ O → 2HAsO ₂ + 3S (1) HAsO ₂ + 1 / 2O ₂ + NaOH → NaH ₂ AsO ₄ (2) HAsO ₂ + 1 / 2O ₂ + 2NaOH → Na ₂ HAsO ₄ + H ₂ O (3) That is, first, according to the formula (1), Arsenic sulfide (As ₂ S ₃ ) contained in the smelting intermediate reacts with oxygen and arsenous acid (H 2
AsO ₂ ) is produced. Then, according to formulas (2) and / or (3), arsenous acid (HAsO ₂ ) reacts with the added alkali, here sodium hydroxide (NaOH), to form arsenate (NaH ₂ AsO _4). , Na ₂ HAsO ₄ ) is produced.

It is also assumed that CuS exerts a catalytic action that contributes to the promotion of the above-mentioned reaction, and that itself repeats the following reaction: CuS → Cu ₂ S → CuS According to the method of the present invention, Utilizing the catalysis of copper increases the availability of oxidants, usually oxygen in the air,
As a result, the leaching rate and leaching rate of arsenic are expected to increase.

Arsenate (NaH ₂ AsO ₄ , Na ₂ HAs when sodium hydroxide is used as alkali)
Since O ₄ ) is water-soluble, it means that arsenic is leached from the smelting intermediate. Then, the used leachate containing arsenic and the leach residue are subjected to solid-liquid separation, and optionally filtered and / or washed to obtain a clear solution in which arsenate is dissolved. By adding, for example, calcium hydroxide, arsenic can be recovered as calcium arsenate in a stable form of substance.

The leach residue is a solid substance obtained by concentrating valuable substances such as copper, zinc and bismuth in a sulfide form, and can be recycled and reused in the smelting process. Further, since copper remains in the leaching residual rhino in the form of sulfide, the leaching residual rhino can be reused as a copper sulfide in the arsenic separation method of the present invention.

[0020]

EXAMPLE 1 A solution containing copper and arsenic obtained by decopperization of an electrolytically refined copper solution was subjected to decopperization using sodium hydrosulfide (NaSH).
Arsenic sulfide was obtained by performing dearsenic treatment. The composition of the solution containing arsenic and copper is as shown in Table 1, and the composition of the obtained arsenic sulfide (copper content as copper sulfide is extremely high at 36.3%) is shown in Table 2. It was on the street.

[0021]

[Table 1]

[0022]

[Table 2]

Next, this arsenic sulfide 163k is placed in a reaction tank.
In addition, 1.3 m ³ of an aqueous solution prepared by dissolving 16.8 kg of NaOH was added. Then, air is blown at a flow rate of 1 m ³ / min, and at the same time, a sodium hydroxide solution having a concentration of 200 g / L is appropriately added to adjust pH to 6.5 to 7.5.
The oxidative leaching step was carried out for 6 hours while maintaining The temperature of the leachate was maintained at 60 ° C during the leaching process.

After that, solid-liquid separation was performed to separate an insoluble residue rhino and a clear liquid. The composition of the obtained clear liquid was as shown in Table 3.

[0025]

[Table 3]

The leaching rate of arsenic was 91.9%. Since there was much copper as copper sulfide in the liquid, the leaching rate of arsenic was as high as 90% or more even at a low temperature of 60 ° C.

Example 2 From the solution containing arsenic and copper obtained in Example 1, only copper was previously removed by sulfurization, and further arsenic was sulfided (the copper content as copper sulfide was 4.5%). And very few).
The composition of the obtained arsenic sulfide was as shown in Table 4.

[0028]

[Table 4]

This arsenic sulfide was treated in the same manner as in Example 1 except that the leaching time was 6 hours and the temperature of the leaching solution was maintained at 60 ° C. during the leaching step. Since the amount of copper sulfide in the reaction solution was extremely small, the leaching rate of arsenic was 61.6%, which was not a very high value.

[0030]

According to the method of the present invention, an efficient and inexpensive method for separating arsenic from a smelting intermediate containing arsenic sulfide is provided. Further, according to the method of the present invention, when the smelting intermediate containing arsenic is obtained from a copper smelting process containing arsenic and copper, it is not necessary to remove copper by fractional sulfurization in advance, and The liquid separation step can be omitted, and the sulfuration step can be relatively easily managed. Therefore, an advantageous method can be provided from the viewpoint of cost reduction by simplifying the step.

Claims (6)

[Claims] 1. A method for separating arsenic from an arsenic sulfide-containing smelting intermediate by subjecting the arsenic sulfide-containing smelting intermediate to an oxidative leaching step in the presence of an alkali to separate arsenic as an arsenate. And the oxidation leaching step is performed in the presence of copper sulfide. 2. The method of claim 1, wherein the alkali is sodium hydroxide. 3. The oxidative leaching step has a pH of 6.5 to 7.5.
The method according to claim 1 or 2, characterized in that 4. The method according to claim 1, wherein the temperature of the oxidation leaching step is 50 to 90 ° C. 5. The method according to any one of claims 1 to 4, wherein the copper sulfide includes one derived from the arsenic sulfide-containing smelting intermediate. 6. The method according to claim 1, wherein the copper sulfide contains an additive.