JP5645457B2 - Method for producing crystalline iron arsenate raw material liquid from smoke ash - Google Patents

Description

  The technology for separating and recovering arsenic from substances containing arsenic and other metal elements, in particular, arsenic contained in smoke ash generated in non-ferrous smelting is used as a raw material solution for producing crystalline iron arsenate. The present invention relates to a technique for separating and recovering a liquid arsenic-containing solution suitable for the above.

Arsenic is a substance with a large environmental load, and its stable treatment method is important from the viewpoint of environmental conservation. In non-ferrous smelting, especially copper smelting, the arsenic content in the ore tends to increase in recent years, and the treatment of arsenic has become an important technical element.
For example, Patent Document 1 has been proposed regarding the arsenic treatment.

  Patent Document 1 uses an acidic solution to leach arsenic and copper from non-ferrous smelting ash to obtain a leachate, and then extract the copper (Cu) by applying a solvent to the leachate to obtain the obtained post-extraction solution. (Raffinate) is provided to the original solution for producing crystalline iron arsenate. Then, it is proposed that the subsequent crystallization of iron arsenate is performed at a pH value of 1 to 2 while coexisting a seed crystal.

  On the other hand, the present applicant discloses, as Patent Document 2, a smoke ash treatment method for separating copper and arsenic from non-ferrous smelted ash containing copper and arsenic. The smoke ash treatment method is to prepare a slurry by mixing non-ferrous smelted smoke ash and water, and by adding an alkaline agent to the slurry, the leaching reaction is controlled within a predetermined pH value range, and a leachate containing copper This is a method for obtaining a leaching residue containing arsenic.

Special table 2008-540824 JP 2009-161803 A

The present inventors have studied Patent Documents 1 and 2 described above, and have found the following problems.
In the method of Patent Document 1, it is difficult to efficiently separate arsenic and copper contained in the smoke ash, and further, Na (sodium) and K (potassium) contained in the smoke ash are transferred to the leachate. There was a problem that it could not be suppressed.
In addition, there was no preparatory treatment for arsenic or copper in the smoke ash before the leaching operation, and treatment could not be performed according to the components of the smoke ash.
As a result, most of Na and K contained in the smoke ash are brought into the post-extraction liquid (raffinate) that is the original liquid for producing scorodite. For this reason, when scorodite is generated at a high temperature and between pH values of 1 to 2, Na-based and K-based jarosite is likely to be generated, and the resulting scorodite's arsenic elution characteristics may be adversely affected. Was a concern.

  Further, since the smoke ash is acid leached, not only arsenic but also readily soluble copper is eluted. For this reason, when the smoke ash contains a large amount of copper, there has been a problem that the equipment for the copper solvent extraction process provided in the next process is increased in size and the equipment investment and running cost are increased.

  Also in the method of Patent Document 2, separation of arsenic from Na and K was not sufficient.

  Furthermore, smoke ash is an emission of non-ferrous smelting process, and the variation range of components and properties is wide and the variation is large. Therefore, the components and properties are unlikely to be constant depending on the location and time of generation of smoke ash. Some smoke ash is difficult to separate from copper and arsenic by wet leaching. However, a technique for treating this hardly separable smoke ash has not been found.

The present invention has been made under the above-described circumstances, and the problem to be solved is an arsenic solution that can efficiently separate copper and arsenic from smoke ash and contains almost no Na and K. The object is to provide a method for producing a crystalline iron arsenate raw material solution that can be provided.
Furthermore, another object of the present invention is to provide a method for producing a crystalline iron arsenate raw material liquid that can be separated by wet treatment even for smoke ash, which is difficult to separate copper and arsenic.

In order to solve the above-mentioned problems, the present inventors have conducted intensive research.
First, we investigated the properties and behavior of various smoke ash. Then, it turned out that there exists a smoke ash which cannot separate copper and arsenic in the leaching of smoke ash according to the prior art, and furthermore, cannot be separated at all.
Therefore, the present inventors can separate copper and arsenic even with smoke ash with poor copper / arsenic separation in the prior art or with smoke ash that is difficult to separate, and furthermore, Na and K are reliably separated. The research of the method that can be done was advanced.

  As a result of the research, the present inventors have improved the copper / arsenic separability by adding an iron source to the ash pulp and neutralizing and leaching, and furthermore, the ash ash is difficult to separate copper and arsenic. However, I came up with an operation called preliminary leaching that would allow separation of copper and arsenic. And even if it is smoke ash that is difficult to separate copper and arsenic by performing the preliminary leaching operation before the leaching operation, copper, Na and K are transferred to the leaching solution, and arsenic is put into the residue. The present invention has been completed by conceiving the epoch-making knowledge that this is possible.

That is, the first invention for solving the above-described problem is
Smoke ash containing copper and arsenic is used as a slurry, and the pH value of the slurry is in the range of 3 to 4, copper is leached into the slurry liquid, and leaching is performed using arsenic as a residue. In the processing method to obtain
Before the said leaching process, it is a manufacturing method of the crystalline iron arsenate raw material liquid from smoke ash which has the process of making the pH value of the said slurry 0.5-2, and performing preliminary leaching .

The second invention is
The preliminary leaching is to dissolve crystalline iron arsenate raw material liquid from smoke ash according to the first invention, wherein Na and / or K is dissolved in the slurry liquid in the slurry. Is the method.

The third invention is
The method for producing a crystalline iron arsenate raw material liquid from smoke ash according to the first or second invention, wherein the residue is dissolved with an acid to obtain an arsenic solution.

The fourth invention is:
In the preliminary leaching step, at least one of an iron source and a hydrogen peroxide solution is further added to the slurry. Crystals from smoke ash according to any one of the first to third inventions It is a manufacturing method of a ferrous iron arsenate raw material liquid.

The fifth invention is:
In the leaching step, any one or more of an iron source and hydrogen peroxide water is further added to the liquid from which the copper has been leached, according to any one of the first to fourth inventions . It is a manufacturing method of the crystalline iron arsenate raw material liquid from smoke ash.

The sixth invention is:
The method for producing a crystalline iron arsenate raw material liquid from smoke ash according to the fourth or fifth invention, wherein the iron source is trivalent iron.

The seventh invention
In a leaching method in which smoke ash generated in non-ferrous smelting containing copper and arsenic is used as a slurry, copper is leached into a slurry liquid, and arsenic is used as a residue, the ash or the slurry contains an iron source and / or hydrogen peroxide. It is a manufacturing method of the crystalline iron arsenate raw material liquid from smoke ash which has adding water.

  According to the method for producing crystalline iron arsenate raw material liquid from smoke ash according to the present invention, solid-liquid separation of copper and arsenic can be efficiently performed from smoke ash containing copper and arsenic, and Na , An arsenic solution containing almost no K can be obtained.

It is a process flow figure showing a manufacturing method of crystalline iron arsenate raw material liquid from smoke ash concerning the present invention.

  Referring to FIG. 1 which is a process flow diagram showing a method for producing crystalline iron arsenate raw material liquid from smoke ash according to the present invention, the smoke ash, preliminary leaching, leaching, and re-leaching with respect to the mode for carrying out the present invention , The soaking operation, and the difficult-to-separate smoke ash treatment will be described in this order.

<Smoke ash>
Smoke ash is generated from each process of non-ferrous smelting. In addition to arsenic and copper, the smoke ash may contain light elements such as Na and K.
The present invention can be effectively applied even to smoke ash containing copper, arsenic, Na, and K generated from a smelting process or the like in copper smelting.

<Preliminary leaching>
Preliminary leaching according to the present invention is an operation in which a liquid of water, process water, acid, etc. is added to the smoke ash described above to make a smoke ash slurry before leaching described later, and the pH value of the slurry is 2 or less. is there. When the pH value of the smoke ash slurry exceeds 2, an acid such as sulfuric acid is added so that the pH value becomes 2 or less. However, the pH value is preferably in the range of 0.5-2. This is because by taking the pH value, light elements such as Na and K are leached into the slurry liquid.

It is desirable to stir the slurry to promote preliminary leaching and homogenize the slurry. This operation can be performed under atmospheric pressure, and the temperature may be from room temperature to about 50 ° C., so that it may be set as appropriate in consideration of cost and the like. The equipment may be a normal reaction vessel. The concentration of the slurry may be determined in consideration of the dissolution amount of copper and light elements.
The stirring time may be about 10 minutes after the pH value of the slurry reaches a predetermined value, depending on the stirring strength.

  As a result of the above-described configuration, light elements such as Na and K are leached into the slurry liquid after preliminary leaching, but these light elements form a slightly soluble compound in a weakly acidic state due to an inorganic acid. This is preferable because there is no fear and dissolution in the liquid is maintained as it is.

  Even if the slurry obtained by the preliminary leaching is used as it is, it becomes a raw material for leaching in the copper arsenic separation step which is the next step. However, the slurry concentration may be adjusted for convenience in the copper arsenic separation step.

<Leaching>
The leaching is performed by adding a pH adjusting agent such as alkali to the slurry after preliminary leaching and adjusting the pH value to 3-4. During leaching, heating, stirring, etc. may be performed simultaneously. Since the slurry after the leaching becomes a residue remaining undissolved with the liquid, solid-liquid separation is performed by filtration or the like. At this time, since Na and K are dissolved in the liquid, they can be separated from the arsenic in the residue.
Since the leaching residue obtained by the solid-liquid separation contains arsenic, re-leaching described later is performed. On the other hand, since the liquid contains a small amount of arsenic in addition to copper, Na, and K, a liquid purification operation described later may be performed.

For the alkali that is a pH adjusting agent used in the leaching, an alkaline agent of an alkaline earth metal can be suitably used. Among these, Ca (OH) ₂ , CaCO _3, Mg (OH) _{2 and the} like are preferable because they are available for general use.

<Releaching>
The re-leaching is an operation of dissolving a residue obtained after the leaching with an acid such as sulfuric acid and re-leaching and then separating the solid and liquid to obtain a re-leaching filtrate containing arsenic.
The re-leaching filtrate was optimal as a raw material liquid for synthesizing iron arsenate crystals because arsenic was dissolved at a high concentration and the concentrations of Na and K were slight.

  By the way, as a result of investigating the behavior of Na and K using various smoke ash by the present inventors, by performing multi-stage leaching operations such as preliminary leaching, leaching and re-leaching according to the present invention, the smoke ash is directly acidified. Compared to the case of leaching, the fact that Na and K in the re-leaching solution can be dramatically reduced to 0.1 g / L or less was confirmed.

The synthesis of iron arsenate crystals from the re-leached filtrate obtained by re-leaching can be performed using a conventional iron addition method. What is necessary is just to make the pH of a liquid about 1-2, add an iron salt, and make it react at a temperature of 50-100 degreeC, stirring, and making it react for 7 to 10 hours. Although it can be applied by an autoclave method, a sufficiently good iron arsenate crystal (scorodite, FeAsO ₄ ) can be obtained by reaction under atmospheric pressure. By using arsenic as crystalline scorodite, stabilized arsenic can be stored.

  Since iron arsenate crystals are formed in the liquid after the iron arsenate crystal formation reaction, the iron arsenate crystals can be recovered by filtration or the like.

<Liquid operation>
The dripping operation is to remove arsenic contained in a small amount in the filtrate obtained by the above-described leaching. In the liquid purification operation, at least one of an iron source and hydrogen peroxide solution is added to the filtrate. At this time, alkali is added and the pH is adjusted to 3 or more, preferably 3.5 or more to obtain a liquid and a residue.
The liquid is a concentrated copper solution that contains almost no arsenic. Therefore, it can be used as a copper raw material that does not give arsenic load to the subsequent process.
In the residue, copper is taken into the iron porcelain, and it can be expected that the porcelain will further adsorb arsenic and move to the leach residue. I can do it.

<Treatment of difficult-to-separate smoke ash>
As described above, the present inventors have investigated the properties and behaviors of various types of smoke ash, and have found that the smoke ash with poor separation between copper and arsenic, and furthermore, cannot be separated at all. Specifically, in the leaching of only an acid solution having a pH value of 3 to 4 according to the prior art, a hard-to-separate smoke ash that makes it difficult to separate copper and arsenic was found.

In the present invention, when targeting the smoke ash having poor separability, the inventors have come up with a configuration in which an oxidizing agent is added in the preliminary leaching or leaching described with reference to FIG. Examples of the oxidizing agent include trivalent iron, hydrogen peroxide, ozone, oxygen gas, and peroxide.
Among these, trivalent iron is preferable because it enters the leaching residue in the leaching step and is leached in the subsequent leaching step, and can be used as an iron source for generating iron arsenate crystals.

  Specifically, an oxidizing agent such as trivalent iron may be added to hardly separable smoke ash or smoke ash slurry. The addition of the oxidant is performed based on the separable state at the time of either preliminary leaching or leaching. A plurality of divided additions may be performed at the same location. However, from the viewpoint of stabilizing the process, it is preferable to add an oxidizing agent during preliminary leaching.

Examples of the trivalent iron compound include ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), iron hydroxide, and goethite. One or more of these are added as they are or in the form of a solution. However, when hydrogen peroxide or the like is used in addition to the iron source, the iron source may be a divalent iron compound.
In the case of adding trivalent iron, the total amount of arsenic contained in the smoke ash is equal to or more than 1 mol, preferably 1.5 mol. The iron source to be added may be solid, as long as it has solubility in the liquid.

  On the other hand, although copper and arsenic are separated, for example, in the case where smoke ash having a poor separation property such that arsenic is leached by 1 g / L or more in the leachate is treated, 0.5% of arsenic contained in the smoke ash is treated. The effect appears sufficiently when trivalent iron is added in a molar amount or less. Therefore, considering the iron source cost, it is preferable to adjust the amount of trivalent iron added according to the properties of the smoke ash to be treated.

  With the above-described configuration in which an oxidant is added during preliminary leaching or leaching, it is possible to separate copper and arsenic even in the case of smoke ash, in which it is difficult to separate copper and arsenic by conventional techniques. As a result, even smoke ash with inferior separability can be leached to transfer copper, Na, and K to the leachate, and arsenic can be introduced into the residue at a high concentration.

The detailed reason why the separation of copper and arsenic is improved by the addition of the iron source described above is not clear. Since the smoke ash sufficiently contains arsenic, if dissolved as it is using an acid or the like, the arsenic in the smoke ash suspended as a solid content in the slurry is considered to dissolve to a solubility that is in equilibrium with the solution.
However, according to the present invention, when an oxidizer such as trivalent iron is added to the slurry, the amount of arsenic dissolved in the liquid remains in spite of the amount of arsenic dissolved in consideration of the theoretical solubility of arsenic. Dissolution of undissolved arsenic therein is suppressed, while other metal elements such as copper and zinc are dissolved, so that arsenic and other metal elements can be separated.

  As described above, the method for treating difficult-to-separate smoke ash and adding the iron source in the preliminary leaching or leaching can be applied to the smoke ash generated in the copper smelting process. In particular, if the separation between copper and arsenic is inferior, and smoke ash with an iron / arsenic mass ratio of 1 or less, further effects can be expected.

  Also in the case of processing difficult-to-separate smoke ash, an arsenic solution containing iron can be obtained by redissolving the obtained residue with an acid such as sulfuric acid. Further, since the re-leaching solution contains almost no Na or K, it can be supplied as a raw material for crystalline iron arsenate having an optimum liquid quality.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
500 dry · g of non-ferrous smelting furnace ash A samples having the component grades shown in Table 1 were prepared. The components were analyzed by ICP (component analysis was also performed by ICP in the following Examples and Comparative Examples).
1000 mL of pure water was used as a solvent for preparing the slurry, and a 2 liter beaker was used as the container. As the stirring device, a two-stage turbine stirring blade equipped with four baffle plates was used.
As an alkaline agent, Ca (OH) ₂ milk (aqueous solution) having a concentration of 200 g / L was prepared. Reaction was performed between 30-35 degreeC.

  1000 mL of pure water and 500 ash · g of smoke ash A sample were added to a 2 liter beaker and stirred for 10 minutes to give a smoke ash slurry. The pH value of the slurry at this time was 2.4. Next, 95% sulfuric acid reagent was added to the slurry to lower the pH value to 1.4, and the mixture was further stirred for 10 minutes for preliminary leaching.

After preliminary leaching, leaching was performed.
Specifically, after stirring by preliminary leaching, an alkaline agent was added to the slurry to neutralize to a set pH value of 3.5. After reaching the set pH, leaching was continued for another 25 minutes while maintaining the set pH, and then stirring was terminated and filtration was performed. The amount of Ca (OH) ₂ liquid used as the alkaline agent was 120 mL.

After collecting the filtrate by filtration, the leaching residue was washed with water in a filter using 1000 mL of pure water. The composition of the obtained filtrate is shown in Table 2.
From the filtrate composition and the balance of the leachate shown in Table 2, it was found that about 80% of the copper in the smoke ash was transferred to the filtrate and about 98% of arsenic was put in the residue.

Next, pure water was added to the total amount of the residue to make a slurry again, and then sulfuric acid was added to perform re-leaching.
Specifically, the amount of pure water used to produce the residue slurry was 370 mL, and a 1-liter beaker was used as the container. The stirrer used 1 stage turbine blades with 4 baffle plates. Sulfuric acid is the reagent 95% sulfuric acid.
Then, 370 mL of pure water and the total amount of the residue were put into a 1 liter beaker and stirred for 15 minutes to form a slurry. Next, 95% sulfuric acid is added to adjust the pH value to 0.3, and leaching is continued for 25 minutes at 30 to 35 ° C. while maintaining the pH value. A re-leaching solution and residue were obtained.
Table 3 shows the composition of the obtained re-leaching solution.
From the results shown in Table 3, a concentrated arsenic solution containing a sufficient amount of iron to form crystalline iron arsenate was obtained as the re-leaching solution. Furthermore, Na and K that form jarosite are hardly contained, the copper content is small, and the liquid quality is sufficient as a raw material liquid for producing iron arsenate crystals (scorodite). confirmed.

(Comparative Example 1)
A re-leaching solution and a residue were obtained by performing the same operation as in Example 1 except that the smoke ash slurry described in Example 1 was used and preliminary leaching was carried out with a pH value of 2 or less.
Table 4 shows the composition of the leachate obtained in the middle, and Table 5 shows the composition of the leaching solution.

  The re-leaching solution according to Comparative Example 1 shown in Table 5 and the re-leaching solution according to Example 1 subjected to the preliminary leaching are compared from the viewpoint as a raw material liquid for producing crystalline iron arsenate. Then, in the re-leaching solution according to Example 1, Na and K are almost completely removed, which is a preferable liquid quality as a raw material for producing iron arsenate crystals. , K was contained at about 1 g / L, which was not preferable as a raw material liquid. This is because jarosite may be formed.

  The details of the compound form in which Na and K are contained in the smoke ash are unknown. However, the present inventors presume that by performing preliminary leaching with a pH of 2 or less according to the present invention, these Na and K compound forms are broken and efficiently leached and removed at the time of preliminary leaching.

  Furthermore, from the comparison of the leachate composition according to Comparative Example 1 shown in Table 4 and the leachate composition according to Example 1, the leachate according to Example 1 is more in the form of copper and arsenic than the leachate according to Comparative Example 1. It was found that the separability was good. This is also evident from the difference in the copper concentration of the re-leaching solution. Here, when the raw material liquid for producing crystalline iron arsenate is used, the lower the copper concentration, the better, but it has been found that the effect of the preliminary leaching is great from this viewpoint.

(Comparative Example 2)
The same smoke ash as in Example 1 was leached by the method according to the prior art.
First, 500 dry · g of the smoke ash A described in Example 1 was prepared.
700 mL of pure water was used as a solvent for preparing the slurry, and a 2 liter beaker was used as the container. The stirrer used was a two-stage turbine blade equipped with four baffle plates. The sulfuric acid used was 95% sulfuric acid as a reagent.

  700 mL of pure water and 500 g of the smoke ash were added to a 2 liter beaker and stirred for 10 minutes to form a slurry. Next, 95% sulfuric acid is added to adjust the pH value to 0.3, and leaching is continued for 25 minutes at 30 to 35 ° C. while maintaining the pH value. Provided. Table 6 shows the composition of the obtained acidic leachate.

  The acidic leachate according to Comparative Example 2 shown in Table 6 is a solution containing no arsenic compared to the re-leaching solution according to Example 1, but the jarosite forming elements Na and K are several g / hr. It was contained in the L order, and further copper was as high as 60 g / L. Therefore, it was found that the raw material liquid for producing iron arsenate has an inappropriate liquid quality. That is, when acid was leached directly by adding acid to the smoke ash A, it was confirmed that Na, K, and copper would inevitably have high concentrations when trying to obtain a solution with a high arsenic concentration.

(Example 2)
A nonferrous smelting furnace smoke ash B sample having component grades shown in Table 7 was prepared at 360 dry · g.
The smoke ash B is copper / arsenic hardly separable smoke ash.

The reagent ferric sulfate was dissolved to prepare a trivalent iron solution having a trivalent iron concentration of 99 g / L.
As a solvent for preparing the slurry, 980 mL of pure water was used, and a 2 liter beaker was used as the container. The stirrer used 4 baffle plate 2 stage turbine blades. Ca (OH) ₂ milk (aqueous solution) having a concentration of 200 g / L was prepared as an alkaline agent. Reaction was performed between 30-35 degreeC.
To a 2 liter beaker, 980 mL of pure water and 360 ash · g of smoke ash B sample were added and stirred for 10 minutes. The pH value of the slurry at this time was 2.5.
Next, 220 mL of trivalent iron solution was added to the slurry, and 95% sulfuric acid was further added to lower the pH value to 0.75, followed by further stirring for 10 minutes, and preliminary leaching was performed. The amount of iron contained in 220 mL of the trivalent iron solution corresponds to a molar amount of 1.5 times the amount of arsenic contained in the smoke ash B sample 360 dry · g.

After completion of the preliminary leaching, an alkali agent was added to the slurry, and neutralized to a set pH value of 3.5. After reaching the set pH, leaching was further carried out for 20 minutes while maintaining the set pH, and the stirring of the slurry was terminated and subjected to filtration. In the leaching, the amount of Ca (OH) ₂ liquid used was 340 mL.

  After collecting the filtrate by filtration, the leaching residue was washed with water in a filter using 1000 mL of pure water. Table 8 shows the composition of the obtained filtrate.

表８に示すろ液組成と、浸出液量のバランスとより、煙灰中の銅の約７５％がろ液に移行し、ヒ素は約９６％が残渣に入れ込まれていることが判明した。

From the filtrate composition and the balance of the leachate shown in Table 8, it was found that about 75% of the copper in the smoke ash was transferred to the filtrate and about 96% of arsenic was put in the residue.

Subsequently, pure water was added to the total amount of the residue to make a reslurry, and then sulfuric acid was added to perform leaching again.
Specifically, the amount of pure water used to produce the residue slurry was 750 mL, and a 2 liter beaker was used as the container. The stirrer used was a two-stage turbine blade equipped with four baffle plates. Sulfuric acid is the reagent 95% sulfuric acid.
Then, 750 mL of pure water and the total amount of the residue were put into a 2 liter beaker and stirred for 15 minutes to form a slurry. Next, 95% sulfuric acid is added to adjust the pH value to 0.5, and leaching is continued for 25 minutes at 30 to 35 ° C. while maintaining the pH value. A re-leaching solution and residue were obtained.
Table 9 shows the composition of the obtained re-leaching solution.

From the results shown in Table 9, a concentrated arsenic solution containing a sufficient amount of iron to form crystalline iron arsenate was obtained as the re-leaching solution. Furthermore, only Na and K forming jarosite are contained in an amount of 0.1 g / L or less, and the content of copper is small, and the liquid quality is sufficient as a raw material liquid for producing iron arsenate crystals (scorodite). It became possible to collect the arsenic solution. This liquid is a preferable liquid quality as an original liquid for producing crystalline iron arsenate.
Further, as shown in Comparative Example 3 to be described later, the smoke ash B cannot be separated and leached of copper and arsenic when only the smoke ash slurry is treated, but the smoke ash slurry is trivalent. By mixing iron and leaching, copper and arsenic can be separated and leached.

(Comparative Example 3)
Leaching was performed by the same operation as in Example 2 except that preliminary leaching with addition of trivalent iron was not performed.
Specifically, 980 mL of pure water and smoke ash sample B360dry · g were added to a 2-liter beaker and stirred for 10 minutes to form a slurry. The pH value of the slurry at this time was 2.5. Next, the Ca (OH) ₂ milk was added to the smoke ash slurry to raise the pH. Then, the viscosity of the slurry gradually increased, and when the pH value was 2.8, stirring was no longer possible and the leaching test was stopped.

  As a result of sampling, the copper concentration at the time was 5.2 g / L and the arsenic concentration was 5.4 g / L, and there was no tendency for copper and arsenic to separate. In any case, since the viscosity of the slurry increases until stirring becomes impossible, it has been found that the copper and arsenic separation and leaching method according to Comparative Example 3 cannot be performed.

Example 3
This example was performed to confirm the effect of adding trivalent iron or hydrogen peroxide, or adding both trivalent iron and hydrogen peroxide when nothing was added to the slurry during leaching. It is.
500 dry · g of non-ferrous smelting furnace smoke ash C was prepared.
Table 10 shows the component quality of the smoke ash C.

1000 mL of pure water was used as a solvent for preparing the slurry, and a 2 liter beaker was used as the container. As the stirring device, a two-stage turbine stirring blade equipped with four baffle plates was used.
As an alkaline agent, Ca (OH) ₂ milk (aqueous solution) having a concentration of 200 g / L was prepared. Reaction was performed between 30-35 degreeC.

(A) When not adding both trivalent iron and hydrogen peroxide 1000 mL of pure water and smoke ash C sample 500dry · g were added to a 2-liter beaker and stirred for 10 minutes to form a slurry. The pH value of the slurry at this time was 2.6.
Next, 95% sulfuric acid was added to adjust the pH value of the slurry to 1.8, and the mixture was further stirred for 10 minutes to perform preliminary leaching.
After completion of the stirring, an alkaline agent was added to the slurry, and neutralized to a set pH value of 3.9. After reaching the set pH, leaching was further carried out for 25 minutes while maintaining the set pH, and the stirring of the slurry was terminated and subjected to filtration.
Table 11 shows the arsenic concentration and the copper concentration of the obtained filtrate.

(B) When hydrogen peroxide solution was added 1000 mL of pure water and 500 ash · g of smoke ash C sample were added to a 2 liter beaker and stirred for 10 minutes to form a slurry. Here, 12.9 ml of 3% aqueous hydrogen peroxide was added, and then 95% sulfuric acid was added to lower the pH value to 1.8, followed by further leaching by stirring for 10 minutes.
After completion of the preliminary leaching, leaching was performed by performing the same operation as in (a) described above to obtain a filtrate.
Table 11 shows the arsenic concentration and the copper concentration of the obtained filtrate.
The amount of hydrogen peroxide described above is an amount corresponding to 1 equivalent of the reaction stoichiometry necessary for oxidizing 1 g / L of trivalent arsenic to pentavalent arsenic.

(C) When trivalent iron is added 1000 mL of pure water and 500 ash · g of smoke ash C sample were added to a 2 liter beaker and stirred for 10 minutes to form a slurry. Here, 21.5 mL of a ferric sulfate solution having an iron concentration of 99 g / L is added, and then the reagent 95% sulfuric acid is added to lower the pH value to 1.8, followed by further stirring for 10 minutes to perform preliminary leaching. Carried out.
After completion of the preliminary leaching, leaching was performed by performing the same operation as in (a) described above to obtain a filtrate.
Table 11 shows the arsenic concentration and the copper concentration of the obtained filtrate.
The amount of iron contained in 21.5 mL of the trivalent iron solution described above corresponds to a molar amount of 0.2 times the amount of arsenic contained in the smoke ash C sample 500 dry · g.

(D) When hydrogen peroxide solution and trivalent iron are added 1000 mL of pure water and smoke ash C sample 500dry · g were added to a 2 liter beaker and stirred for 10 minutes to form a slurry. Here, 12.9 mL of 3% hydrogen peroxide solution and 21.5 mL of ferric sulfate solution having an iron concentration of 99 g / L were added, and then the reagent 95% sulfuric acid was added to adjust the pH value to 1.8. And further leaching was performed by stirring for 10 minutes.
After completion of the preliminary leaching, leaching was performed by performing the same operation as in (a) described above to obtain a filtrate.
Table 11 shows the arsenic concentration and the copper concentration of the obtained filtrate.

(Considerations a to d)
In the test result of (a), since 1 g / L of arsenic remained in the leachate, the non-ferrous smelting furnace smoke ash C was found to have slightly inferior copper and arsenic separability.
However, from the test results of (b) to (d), even in the case of smoke ash C with slightly inferior separation of copper and arsenic, at the time of leaching, addition of hydrogen peroxide or trivalent iron, or hydrogen peroxide and trivalent It has been found that the addition of iron can improve the separability of copper and arsenic with little effect on the copper leaching rate.
In particular, “(c) when trivalent iron is added” and “(d) when hydrogen peroxide solution and trivalent iron are added”, the addition amount of trivalent iron or hydrogen peroxide solution is small. Nevertheless, the separability of copper and arsenic is remarkably improved and the addition operation is simple, so it is considered to be a very effective means in actual operation.

Example 4
In Example 4, trivalent iron, hydrogen peroxide, or the filtrate obtained in “(a) When both trivalent iron and hydrogen peroxide added are not added” in Example 3 described above, or This was done to confirm the effect when both trivalent iron and hydrogen peroxide were added.

(E) When hydrogen peroxide solution is added 150 mL of the filtrate obtained in “(a) When both trivalent iron and hydrogen peroxide are not added” in Example 3 described above is prepared and used as the original solution. .
In a 300 ml beaker, weigh 150 mL of the original solution, add 1.9 mL of 3% hydrogen peroxide, then add 95% sulfuric acid reagent to lower the pH value to 1.8, and stir for another 10 minutes. It was.
After the stirring, an alkaline agent was added to the original solution to neutralize to a preset pH value of 3.9. After reaching the set pH, the reaction was continued for 15 minutes while maintaining the set pH value, and then stirring of the reaction source liquid was terminated and subjected to filtration to obtain a filtrate.
Table 12 shows the arsenic concentration and copper concentration of the filtrate obtained.
In addition, the ratio of the addition of 1.9 mL of 3% hydrogen peroxide solution to 150 mL of the filtrate is the same as the addition ratio of 12.9 mL of 3% hydrogen peroxide solution to the 1000 mL of pure water used explained in Example 3 above. It is set according to this.

(F) When trivalent iron is added Weigh 150 mL of the original solution into a 300 ml beaker, add 3.2 mL of a ferric sulfate solution with an iron concentration of 99 g / L, and then add a reagent 95% sulfuric acid to adjust the pH. The value was lowered to 1.8 and stirred for another 10 minutes.
After the stirring, the same operation as (e) described above was performed to obtain a filtrate.
Table 12 shows the arsenic concentration and copper concentration of the filtrate obtained.
The ratio of the addition of 3.2 mL of the ferric sulfate solution with an iron concentration of 99 g / L to 150 mL of the filtrate is the same as that of the second sulfuric acid with an iron concentration of 99 g / L with respect to the 1000 mL of pure water used explained in Example 3 above. It is set according to the ratio of addition of 21.5 mL of iron solution.

(G) When hydrogen peroxide solution and trivalent iron are added 150 mL of the original solution is weighed into a 300 ml beaker, 1.9 mL of 3% hydrogen peroxide solution, and ferric sulfate solution 3 with an iron concentration of 99 g / L 2 mL was added, and then the reagent 95% sulfuric acid was added to lower the pH value to 1.8 and stirring was continued for another 10 minutes.
After the stirring, the same operation as (e) described above was performed to obtain a filtrate.
Table 12 shows the arsenic concentration and copper concentration of the filtrate obtained.

(Consideration of eg)
From the test results of (e) to (g), the addition of hydrogen peroxide or trivalent iron, or the addition of hydrogen peroxide and trivalent iron to the leach filtrate is a concentrated copper solution. Nevertheless, it has been found that arsenic removal is very effective.
In particular, in “(g) When hydrogen peroxide solution and trivalent iron were added”, arsenic could be removed almost completely. As a result, it became possible to prevent the diffusion of arsenic from the filtrate subjected to the treatment (g) to the subsequent steps of recovering copper, and to bring about a meaningful result in terms of environmental conservation. .

  Further, the reaction product recovered in the tests (e) to (g) contains some copper. The reaction product (trivalent iron) still has the ability to adsorb arsenic. Therefore, it is preferable to collect these reaction products, return them to the preliminary leaching step, and use them again in the leaching step. By recovering the reaction product and reusing it in the leaching process, trivalent iron is effectively utilized in the leaching process, and the amount of newly added trivalent iron can be reduced. As a result, not only cost reduction is achieved, but also the actual operation greatly contributes to stabilization of the leaching process.

Claims (7)

Smoke ash containing copper and arsenic is used as a slurry, and the pH value of the slurry is in the range of 3 to 4, copper is leached into the slurry liquid, and leaching is performed using arsenic as a residue. In the processing method to obtain
A method for producing a crystalline iron arsenate raw material liquid from smoke ash, comprising a step of performing preliminary leaching with the slurry having a pH value of 0.5 to 2 before the leaching step.   The method for producing a crystalline iron arsenate raw material liquid from smoke ash according to claim 1, wherein the preliminary leaching is to dissolve Na and / or K in the slurry liquid in the slurry. . The method for producing a crystalline iron arsenate raw material liquid from smoke ash according to claim 1 or 2, wherein the residue is dissolved with an acid to form an arsenic solution. In the preliminary leaching step, the to the slurry, further comprising adding any one or more of the iron source or hydrogen peroxide, crystalline human from smoke ash according to claim 1 Manufacturing method of iron oxide raw material liquid. From the smoke ash according to any one of claims 1 to 4, wherein in the leaching step, at least one of an iron source and hydrogen peroxide water is further added to the liquid from which the copper has been leached. Of manufacturing crystalline iron arsenate raw material liquid. The method for producing a crystalline iron arsenate raw material liquid from smoke ash according to claim 4 or 5, wherein the iron source is trivalent iron. In the leaching method in which smoke ash generated in non-ferrous smelting containing copper and arsenic is used as a slurry, copper is leached into a slurry liquid, and arsenic is used as a residue.
The manufacturing method of the crystalline iron arsenate raw material liquid from smoke ash which has adding an iron source and / or hydrogen peroxide water to the said smoke ash or the said slurry.

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