JPH0625763A - Treatment of intermediate product of smelting - Google Patents

Abstract

PURPOSE:To enable the economical treatment of the intermediate product of smelting by sending a leaching liquid to a neutralizing stage, adjusting this liquid to specific pH and integrally settling and separating arsenic and copper. CONSTITUTION:The intermediate product of smelting consisting of acid soluble metal groups contg. at least the arsenic and cadmium and the copper is subjected to a leaching treatment with the acidity of sulfuric acid. The leaching liquid obtd. in such a manner is sent to a neutralizing stage and is adjusted to >=4.5 and <=6pH, by which the arsenic and copper are integrally settled and separated. The amt. of the arsenic contained in the liquid to be subjected to the neutralization treatment is specified to a range of (molar number of the arsenic) <=1/2 (molar number of the copper)+(molar number of iron). Hydrogen sulfide, sodium hydrogensulfide or zinc powder is added to the liquid obtd. after the settlement and sepn. of the arsenic and copper, by which the cadmium is settled and separated. As a result, the copper is economically recovered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of treating smelting intermediate products such as smoke ash generated during copper smelting and copper-containing dross generated during lead smelting.

[0002]

2. Description of the Related Art When smelting copper, smoke ash containing impurities such as lead, bismuth, zinc, arsenic and cadmium in addition to copper is produced as a smelting intermediate product. Further, when smelting lead, copper as an impurity in addition to lead and, in some cases, copper-containing dross containing cadmium, zinc, arsenic, etc. are produced as a smelting intermediate product. Some or all of these smelting intermediate products are extracted from the main process in order to remove components other than the intended components, that is, impurities from the system. Then, after being separated into each component and collected, it is effectively used.

For example, smoke ash generated during copper smelting, that is, a smelting intermediate product containing impurities such as lead, bismuth, zinc, arsenic and cadmium in addition to copper has been treated as shown in FIG. First, acid-soluble metals such as copper, arsenic, zinc and cadmium are leached with sulfuric acid to separate them from the leaching slag (leaching step 1). The leachate contains lead, bismuth, antimony, etc. The lead-containing leach slag is used as a lead smelting raw material.
Next, the leachate is treated by an appropriate method among the following treatment methods. First, iron sulfate or iron chloride is added to the leachate to neutralize it while oxidizing arsenic to remove arsenic as iron arsenate (oxidation / neutralization step 2). The removed iron arsenate is sent to the smelting process of copper smelting for processing. In the mother liquor from which iron arsenate has been removed,
Zinc dust is added and copper and cadmium are sequentially separated by zinc dust cementation (cementation step 3). Thereafter, the mother liquor is concentrated or neutralized to recover zinc (concentration / neutralization step 4). After removing arsenic in the above-mentioned oxidation / neutralization step 2, zinc powder is added to the mother liquor to separate only copper by zinc powder cementation (cementation step 5), and the mother liquor is concentrated or neutralized to obtain zinc. And cadmium are simultaneously recovered (concentration / neutralization step 6). If the leaching solution contains a large amount of arsenic, H
_{After the addition of 2} S, NaHS or the like to remove arsenic as a sulfide (sulfurization step 7), the treatment described above or may be performed.

The copper and arsenic recovered as described above are usually sent to a copper smelting process, and zinc and cadmium are sent to a zinc smelting process.

The method for treating copper smelting smoke ash as described above includes
There were the following problems. Treatment costs are high due to the use of relatively expensive iron reagents or sulfiding agents to remove arsenic from the leachate. When an iron reagent is used to remove arsenic from the leachate, the amount of the added iron reagent increases the amount of precipitation, and thus the treatment of the precipitate is expensive. When a sulfiding agent is used to remove arsenic from the leachate, the amount of precipitate is also large because the dehydration property of arsenic sulfide is extremely poor. The above treatment method is advantageous when the concentration of copper in the smoke ash is low and the concentration of zinc is high. However, on the contrary, when the copper concentration is high and the zinc concentration is low, a large amount of zinc powder is required when separating and recovering copper from the leachate, and the zinc used here is recovered when the mother liquor is concentrated and recovered. It is economically disadvantageous in that it requires a large amount of energy.

Next, a method for treating a smelting intermediate product containing copper and lead as main components, which is produced during lead smelting, that is, a copper-containing dross will be described. Conventionally, copper-containing dross has been processed by a dry process in which it is dissolved in a short rotary furnace, an electric furnace or the like, and separated into copper river and crude lead. However, in this treatment method, since a considerable amount of lead is mixed into the copper river, there is a problem that lead loss is caused and lead harmful to copper smelting is brought into the copper smelting process.

Therefore, recently, copper is leached from the copper-containing dross using sulfuric acid or ammonia, and solvent extraction and electrowinning are performed from the obtained leachate (hereinafter referred to as SX / E).
In many cases, electrolytic copper is directly recovered. However, in this treatment method, when the raw material used for lead smelting contains components soluble in sulfuric acid or ammonia such as cadmium, zinc, and arsenic as well as copper, these will accumulate in the leachate. In the end, it is necessary to perform a treatment for removing the copper smelting ash by the same method as that for treating the copper smelting ash, which is economically disadvantageous. When the SX / EX method is carried out using a smelting intermediate product such as copper-containing dross as a raw material, the production scale is
It is about 1/10 of the economically manufacturable scale, and this is also an economically disadvantageous treatment method for copper-containing dross.
Further, electrolytic extraction requires about 10 times as much electric energy as electrolytic refining, and thus this method of treating copper-containing dross is disadvantageous in principle.

The present invention has been made in view of the above circumstances, and can economically process a smelting intermediate product containing an acid-soluble metal such as arsenic and cadmium together with copper, particularly a smelting intermediate product containing a large amount of copper. The purpose is to provide a method.

[0009]

In the method for treating a smelting intermediate product of the present invention, the smelting intermediate product is leached with sulfuric acid acidity,
The leachate thus obtained was sent to the neutralization step to adjust the pH to 4.5 or more and 6 or less, and the arsenic and copper were collectively precipitated and separated to solve the above problems. P in the neutralization step
When H is less than 4.5, arsenic remains in the liquid. If the pH exceeds 5, cadmium (and zinc, if zinc is contained) in the leachate will become hydroxide and precipitate with arsenic and copper. The precipitate is used as a raw material for copper smelting. There is a problem that it cannot be used as it is.

The amount of arsenic contained in the liquid to be subjected to the neutralization step is preferably in the range represented by the following formula (I). (Mole number of arsenic) ≤ 1/2 (Mole number of copper) + (Mole number of iron) (I) If the amount of arsenic in the leachate is out of this range, the leachate contains copper. It is also possible to add iron or iron to satisfy the above conditions. As a method for treating the liquid (hereinafter referred to as the filtrate of the neutralization step) obtained by the precipitation and separation of arsenic and copper obtained by the method of treating the smelting intermediate product of the present invention, hydrogen sulfide, A method in which sodium hydrogen sulfide or zinc powder is added to precipitate and separate cadmium, and a method in which sodium hydroxide or the like is added to the filtrate to raise the pH and precipitate and separate cadmium as hydroxide can be adopted. In the case of the method described below, when zinc is contained in the leachate, this zinc is also precipitated and separated simultaneously with cadmium. Examples of the smelting intermediate product that is the target of the treatment method of the present invention include smoke ash generated during copper smelting (copper smelting smoke ash) and copper-containing dross generated during lead smelting.

(Detailed Description 1 of the Invention) Next, the method for treating a smelting intermediate product of the present invention will be described more specifically with reference to the drawings. FIG. 1 is a flowchart showing an example of the processing method of claim 3. In this treatment method, copper smelting ash or copper-containing dross containing acid-soluble metals such as arsenic, cadmium and zinc and acid-insoluble metals such as lead, bismuth, antimony and copper can be treated. In this treatment method, sulfuric acid is first added to the smelting intermediate product, and leaching treatment of copper, arsenic, etc. is performed while blowing air or oxygen (leaching step S1), and insoluble lead, bismuth, and antimony are separated as leaching sludge. To do. This leach slag is sent to the lead smelting process. On the other hand, calcium carbonate or calcium hydroxide is added to the leachate to perform a neutralization treatment for adjusting the pH to 4.5 to 6 (neutralization step S2). When the pH is adjusted to this range, arsenic and copper are simultaneously precipitated and separated. The residue produced in this neutralization process is sent to the copper smelting process. Next, hydrogen sulfide, sodium hydrogen sulfide or zinc dust is added to the filtrate of the neutralization step. Then, the cadmium contained in the mother liquor is sulfided or zinc dust cemented and precipitated and separated (Cd removing step S3). After this, the pH of the mother liquor from which cadmium has been removed is raised (pH adjusting step S4). In the pH adjusting step S4 of this processing method, it is advisable to adjust the pH to 5 to 9 using calcium hydroxide. In this way, zinc is removed in the state of being hydroxide.

According to this treatment method, copper is recovered as a mixture of copper arsenate and copper hydroxide. This mixture can be used as a raw material for copper smelting. Since the arsenic-containing residue recovered by the conventional treatment method is generally treated in the smelting step of copper smelting, there is no problem in treating the copper arsenate in the smelting step.
In addition, when the mixture containing copper is treated in the copper smelting step, it can be treated at a lower cost than when copper is recovered by the SX / EW method described in the conventional treatment method. It is also advantageous in that it is not necessary to provide equipment for the SX / EW method or to arrange personnel only for copper recovery.

(Detailed Description 2 of the Invention) FIG. 2 shows an example of the processing method of claim 4. With this processing method,
As in the method shown in FIG. 1, a smelting intermediate product leaching step S1
And the neutralization step S2, immediately after the pH adjustment step S5
(Hereinafter, referred to as (deformed) pH adjusting step S5). In the (deformed) pH adjusting step S5 of this treatment method, it is preferable to raise the pH to 5 to 9 using sodium hydroxide. By doing so, zinc and cadmium become hydroxides and precipitate in a mixed state.

[0014]

In the treatment method of the present invention, the smelting intermediate product consisting of the acid-soluble metal group containing at least arsenic and cadmium and copper is leached with sulfuric acid, and the leachate thus obtained is sent to the neutralization step to have a pH of 4. Adjust to 5 or more and 6 or less. By doing this, copper and arsenic form a double salt and are precipitated and removed (if the liquid to be neutralized contains iron or zinc, arsenic also forms a double salt. Removed). As described above, according to this treatment method, arsenic is precipitated and removed together with copper, which simplifies the treatment process and uses an expensive iron reagent or sulfidizing agent only for removing arsenic as in the conventional method. No need. In addition, it is possible to avoid an increase in the cost for treating the precipitate due to the use of these chemicals. Therefore, according to this treatment method, a smelting intermediate product containing an acid-soluble metal such as arsenic and cadmium together with copper can be treated economically.
Moreover, in this treatment method, without using zinc dust,
Since copper is recovered in the neutralization step S2 of ~ 6, copper can be recovered economically even when processing a smelting intermediate product having a high copper concentration and a low zinc concentration.

Further, in the treatment method of claim 2, since the number of moles of arsenic contained in the liquid to be neutralized is less than the sum of half of (the number of moles of copper) and (the number of moles of iron). , Trivalent arsenic contained in the leachate is Cu (AsO
₂ ) ₂ , FeAsO ₄ .2H ₂ O can be almost completely precipitated and removed in the form of a double salt. If arsenic remains in the mother liquor, arsine may be generated when cadmium is subjected to zinc powder cementation in the Cd removing step S3, which is not desirable, but such a possibility can be avoided by this treatment method. Further, even when cadmium and zinc are simultaneously removed as hydroxides in the (deformation) pH adjusting step S5, if arsenic remains, there is a disadvantage that the load of wastewater treatment becomes high. Inconvenience can be avoided.

[0016]

【Example】

(Example 1) 60 tons of copper smelting smoke ash having the composition shown in Table 1 was treated by the treatment method shown in FIG. First, 240 m ³ of waste acid from a sulfuric acid plant (50 g / l of H ₂ SO ₄ ) was added to this copper smelting ash to pulp, and then 14.7 tons of concentrated sulfuric acid was added, while blowing air at 1 Nm ₃ / min, ℃
Was leached for 1 hour (leaching process step S1). Then, the leachate was filtered off with a filter press. Then, 30% calcium carbonate slurry was added to the leachate to adjust the pH to 5.1.
And held for 30 minutes (neutralization step S2). Then, this liquid was subjected to a centrifuge and the residue was filtered off. Next, a 50% NaOH solution is added to the filtrate obtained in the neutralization step S2 to adjust the pH to 8
And left for 1 hour ((deformation) pH adjusting step S5).
Then, this solution was subjected to a filter press to separate the residue and the filtrate. The filtrate was 280 m ³ . This filtrate contained almost no impurities and could be discharged as it was. Table 1 shows the amount of the substances generated or used in each step and the ratio of the metal components contained in them.

[0017]

[Table 1]

Looking at the column of the filtrate of the neutralization step in Table 1, it can be seen that the copper and arsenic in the leachate could be almost completely removed in the neutralization step S2 in which the calcium carbonate slurry was added.

Example 2 8.75 tons of copper-containing dross produced from lead smelting and 10 tons of smoke ash produced from copper smelting were treated by the treatment method shown in FIG. The compositions of these copper-containing dross and smoke ash are shown in Table 2. First the copper containing dross, and waste 39m ³ of sulfuric acid plant, the low load wastewater 23.45M ³ generated in the smelting plant, and concentrated sulfuric acid 6.5 t,
0.2 ton of hydrochloric acid was added, and leaching treatment was performed at 70 ° C. for 3 hours while blowing oxygen at 50 Nm ³ / Hr. After that, 10 tons of copper smelting ash was further added and further leached at 60 ° C. (leaching step S1). Then, the leachate was filtered off with a filter press. After this, 30% calcium carbonate slurry and 25% slaked lime slurry were added to the leachate to adjust the pH.
It was set to 5.6 and held for about 1 hour (neutralization step S2). After this, this liquid was separated into a filtrate and a residue by a filter press. Next, 0.11 ton of zinc dust was added to this filtrate to obtain 1
The mixture was stirred for an hour (Cd removal step S3). After this, the filtrate and the residue were separated by a filter press. The filtrate generated here was returned to the wastewater treatment facility for treatment and then discharged.
Table 2 shows the amounts of the substances generated or used in each step and the ratios of the metal components contained in them.

[0020]

[Table 2]

Looking at the column of the filtrate of the neutralization step in Table 2, it is found that the copper and arsenic in the leachate could be almost completely removed in the neutralization step S2.

[0022]

As described above, in the treatment method of the present invention, the smelting intermediate product consisting of the acid-soluble metal group containing at least arsenic and cadmium and copper is leached with sulfuric acid, and the leachate thus obtained is treated. Send to neutralization step pH 4.
Adjust to 5 or more and 6 or less. By doing this, copper forms a double salt with arsenic and is removed by precipitation. (If iron or zinc is contained in the liquid to be neutralized, arsenic also forms a double salt. Removed). As described above, according to this treatment method, arsenic is precipitated and removed together with copper, so that the treatment process is simplified and a relatively expensive iron reagent or sulfidizing agent is used only to remove arsenic as in the conventional method. No need to use. In addition, it is possible to avoid an increase in the cost for treating the precipitate due to the use of these chemicals. Therefore, according to this treatment method, a smelting intermediate product containing an acid-soluble metal such as arsenic and cadmium together with copper can be treated economically. Further, in the treatment method of the present invention, the recovery of copper is performed without using zinc dust.
Since it is performed in the neutralization step of 4.5 to 6, copper can be economically recovered even when processing a smelting intermediate product having a high copper concentration and a low zinc concentration. In the treatment method according to claim 2, since the number of moles of arsenic contained in the liquid to be subjected to the neutralization step is equal to or less than the sum of half of (the number of moles of copper) and (the number of moles of iron), the leachate Of trivalent arsenic contained in Cu (A
It can be almost completely precipitated and removed in the form of a double salt of sO ₂ ) ₂ and FeAsO ₄ .2H ₂ O. If arsenic remains in the mother liquor, arsine may be generated during the zinc powder cementation of cadmium, which is not desirable, but this treatment method can avoid such a risk. Further, even when cadmium and zinc are simultaneously removed as hydroxides, if arsenic remains, there is a problem that the load of wastewater treatment becomes high, but this process method can also avoid this problem.

[Brief description of drawings]

FIG. 1 is a flowchart showing an example of a method for treating a smelting intermediate product according to the present invention.

FIG. 2 is a flowchart showing another example of the method for treating a smelting intermediate product of the present invention.

FIG. 3 is a flowchart showing a conventional method for treating a smelting intermediate product.

[Explanation of symbols]

 S1 Leaching step S2 Neutralizing step S3 Cd removing step S4 pH adjusting step S5 (deformation) pH adjusting step

Claims (6)

[Claims] 1. A smelting intermediate product consisting of an acid-soluble metal group containing at least arsenic and cadmium and copper is leached with sulfuric acid, and the leachate thus obtained is sent to a neutralization step to a pH of 4.5 or more and 6 or less. A method for treating a smelting intermediate product, which comprises adjusting and precipitating and separating arsenic and copper all together. 2. The amount of arsenic contained in the liquid to be neutralized is within the range of (the number of arsenic moles) ≦ 1/2 (the number of moles of copper) + (the number of moles of iron). The method for treating a smelting intermediate product according to claim 1, wherein 3. The method for treating a smelting intermediate product according to claim 1, wherein hydrogen sulfide, sodium hydrogen sulfide or zinc powder is added to a liquid obtained by separating arsenic and copper by precipitation to separate cadmium by precipitation. A method for treating a smelting intermediate product characterized by the above. 4. The method for treating a smelting intermediate product according to claim 1, wherein the pH of a liquid obtained by precipitating and separating arsenic and copper is increased, and cadmium is precipitated and separated as hydroxide. Processing method of wrought intermediate products. 5. The method for treating a smelting intermediate product according to claim 1, wherein the smelting intermediate product is smoke ash generated during copper smelting. 6. The method for treating a smelting intermediate product according to claim 1, wherein the smelting intermediate product is a copper-containing dross generated during lead smelting.