JP6193603B2 - Method for producing scorodite from non-ferrous smelting ash - Google Patents

Description

  The present invention relates to a method for producing scorodite from non-ferrous smelting ash, which produces scorodite from arsenic (As) contained in the ash produced in the non-ferrous smelting step.

  Arsenic is a substance with a large environmental load, and its stable treatment 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 it is an urgent task to establish a high-load operation system for arsenic. In order to build this system, a large amount of arsenic is concentrated in the smelter ash generated in the smelting process, so it is necessary to actively discharge the arsenic out of the system. For this reason, the arsenic emission is an important technical element. In this case, it is preferable in terms of environmental measures that the discharged arsenic is discharged after being treated with crystalline iron arsenate (scorodite), which is the most stable compound.

Regarding the arsenic treatment, the applicant has applied for Patent Documents 1, 2, 3 and 4.
In Patent Document 1, a non-ferrous smelting ash and water are mixed to prepare a slurry, which is controlled within a predetermined pH value range by adding an alkaline agent to the slurry, and a leaching solution containing Cu and arsenic are obtained by a leaching reaction. It is a method of obtaining the leaching residue containing. Then, the leaching residue containing arsenic is re-leached with an acid to obtain an arsenic solution, the arsenic solution is sulfided to recover arsenic as arsenic sulfide, and the arsenic sulfide is used as an arsenic raw material source for producing crystalline iron arsenate. To do.

  In Patent Document 2, a non-ferrous smelting ash and water are mixed to produce a slurry, and sulfuric acid is added to the slurry to perform primary leaching, and the slurry after completion of the primary leaching step is subjected to solid-liquid separation. Neutralizing agent is added to the obtained primary leachate to neutralize, and the slurry after completion of the neutralization step is subjected to solid-liquid separation. An oxidant is added to the obtained neutralized solution to complete the oxidation step. The latter slurry is solid-liquid separated to obtain an oxide deposit, and the oxide deposit and water are mixed to produce a slurry. Then, sulfuric acid is added to the slurry to perform secondary leaching, and crystallinity as a secondary leaching solution. An arsenic solution is obtained as a raw material for producing iron arsenate.

  In Patent Document 3, a non-ferrous smelting smoke ash and water are mixed to produce a slurry, which is controlled within a predetermined pH value range by adding an alkaline agent to the slurry, performs primary leaching, and the primary leaching process ends. The resulting slurry is separated into solid and liquid, and the resulting primary leaching residue and water are mixed to prepare a slurry. Then, sulfuric acid is added to the slurry to perform secondary leaching, and after completion of the secondary leaching step, the slurry is removed. Solid-liquid separation, neutralization was performed by adding alkali to the obtained secondary leachate, and the slurry after the neutralization step was solid-liquid separated, and an oxidant was added to the resulting neutralized solution, The slurry after completion of the oxidation step is subjected to solid-liquid separation to obtain an oxidized precipitate, and the oxidized precipitate and water are mixed to prepare a slurry, and sulfuric acid is added to the slurry and tertiary leaching is performed. An arsenic solution as a raw material for producing crystalline iron arsenate is obtained as a leachate.

  In Patent Document 4, a non-ferrous smelting ash and water are mixed to produce a slurry, sulfuric acid is added to the slurry to perform primary leaching, and a neutralizing agent and the like are added to the slurry after the completion of the primary leaching process. Then, after adjusting the pH value, an oxidizing agent is added to perform oxidative leaching, and the resulting oxidative leaching residue and water are mixed to prepare a slurry, and sulfuric acid is added to the slurry to perform secondary leaching and secondary leaching. An arsenic solution as a raw material for producing crystalline iron arsenate is obtained as a leachate.

JP 2009-161803 A Japanese Patent Application No. 2011-241731 Japanese Patent Application No. 2011-241732 Japanese Patent Application No. 2011-241730

Patent Document 1 described above is an excellent method for obtaining an arsenic raw material source for producing crystalline iron arsenate from non-ferrous smelting ash. However, according to the study by the present inventors from the viewpoint of constructing a high-load operation system for arsenic, the following problems have been clarified.
1. A sulfiding agent is required to convert arsenic contained in non-ferrous smelting ash into arsenic sulfide. Further, a cost for leaching the generated arsenic sulfide is generated, and further, an Fe source necessary for producing crystalline iron arsenate needs to be supplied from the outside. That is, the drug cost may increase.
2. A step of recovering arsenic contained in non-ferrous smelting ash as arsenic sulfide and a step of leaching arsenic sulfide to produce an arsenic solution again are required. Furthermore, most of the arsenic sulfide produced is trivalent arsenic. For this reason, a step of oxidizing the trivalent arsenic to pentavalent arsenic is also required. As a result, the processing steps from the introduction of non-ferrous smelting ash to the recovery of a liquid arsenic-containing solution suitable as a raw material liquid source liquid for producing crystalline iron arsenate, and further the recovery of crystalline iron arsenate are prolonged. .

Patent Documents 2 to 4 are inventions improved from Patent Document 1 described above, and most of arsenic can be recovered as a pentavalent arsenic solution without using a sulfurizing agent when recovering arsenic from non-ferrous smelting ash. This is a method for leaching arsenic from non-ferrous smelting ash that can shorten the treatment process until crystalline iron arsenate is recovered.
However, as a result of further studies by the present inventors, the following problems have been clarified in Patent Documents 2 to 4.
1. Problems Common to Patent Documents 2 to 4 The arsenic solution used as a raw material for producing crystalline iron arsenate according to Patent Documents 2 to 4 contains a large amount of impurity elements (Bi, Pb, Sb, Sn, etc.). There was a case. If the arsenic solution contains a large amount of the impurity element, the scorodite crystal production may be adversely affected, and a reduction in the amount of the impurity element has been desired. Further, most of the Fe in the arsenic solution is trivalent Fe. From the viewpoint of enlarging the crystal particles of scorodite, it has been desired to convert Fe in the arsenic solution to divalent Fe.
2. Individual Problems of Patent Documents 2 to 4 Compared with Patent Document 1, Patent Documents 2 and 3 have a shorter period until crystalline iron arsenate is obtained, but further reduction in the number of processes is desired. The method of Patent Document 4 realizes the reduction of the number of processes. However, since the arsenic solution obtained in Patent Document 4 has a high acid concentration, there has been a problem that a neutralization treatment or the like is required in order to use the arsenic solution as a crystallization liquid.

  The present invention has been made under the above-mentioned circumstances, and the problem to be solved is arsenic from non-ferrous smelting ash (which may be described as “smelting ash” in the present invention). In the recovery of the arsenic solution containing a high concentration of leachable arsenic without using a sulfurizing agent, and the arsenic solution can be directly used for scorodite crystal production. Impurity elements that adversely affect scorodite crystal production have been reduced, most of the contained Fe is divalent Fe, and the liquid quality (acid concentration) has been appropriately adjusted, while shortening the treatment process and chemicals It is to provide a method for producing scorodite from non-ferrous smelting ash that enables cost reduction.

In order to solve the above-mentioned problems, the present inventors have conducted intensive research.
In order to solve the problem, first, in the primary leaching step according to the above-described conventional technique, almost all of the arsenic remaining in the leachate is introduced into the primary leaching residue, followed by the secondary leaching. In the leaching step, the obtained primary leaching residue is leached under acidity to obtain a secondary leaching solution containing arsenic. Preferably, the obtained secondary leaching solution is repeated to the secondary leaching step to obtain a secondary leaching solution. The step of concentrating the arsenic in the solution, followed by neutralizing excess acid in the secondary leachate enriched in the arsenic and removing impurity elements (impurity heavy metals) that adversely affect scorodite crystal production And, the inventors came up with a process of adjusting most of the dissolved Fe to divalent Fe. In other words, if these steps can be realized, the secondary leaching solution in which the arsenic is concentrated becomes a liquid arsenic solution applicable to the scorodite crystal manufacturing step.

The inventors have further studied the configuration for realizing the above-described steps.
As a result, when water was added to the non-ferrous smelting smoke ash to form a slurry, it was found that almost the same amount of trivalent arsenic was already dissolved in the slurry as when it was eluted under strong acidity.
Based on this knowledge, the present inventors oxidized the trivalent arsenic to pentavalent arsenic in the optimum pH range, so that most of the arsenic dissolved in the slurry in the primary leaching step was converted to the primary as a pentavalent arsenic compound. I came up with a configuration that can be put into the leach residue.

  In addition, the neutralization of the excess acid content of the secondary leaching solution confirms that the primary leaching residue can be used as a neutralizing agent, which can reduce the chemical cost. Bi, Sb, Pb dissolved by adding tritium Fe to divalent Fe while reducing the reduction of pentavalent arsenic in the slurry by adding the selected liquid conditioner to the slurry and reacting with stirring. It has been found that a heavy metal impurity element that adversely affects the scorodite crystallization reaction, such as Sn, is removed to a low concentration. The arsenic solution obtained by filtering the slurry after the above treatment is optimal for the production of scorodite crystals, confirming that the obtained scorodite has excellent elution characteristics, and completed the present invention. It was.

That is, the first invention for solving the above-described problem is
A method for obtaining scorodite from non-ferrous smelting ash containing arsenic, Fe and Cu,
Slurry the non-ferrous smelting ash and add a pH adjuster. Add the oxidant while controlling the pH value of the non-ferrous smelting ash slurry within the range of 1.5 to 3.0. A primary leaching end slurry, and filtering the primary leaching end slurry to obtain a primary leaching solution and a primary leaching residue;
Slurrying the primary leaching residue, adding sulfuric acid, acid leaching to form a secondary leaching complete slurry, and filtering the secondary leaching complete slurry to obtain a secondary leaching solution and a secondary leaching residue; ,
The primary leaching residue is added to the secondary leaching solution to neutralize the acid content in the secondary leaching solution to obtain a neutralized slurry, and then dissolved in the neutralized slurry in the neutralized slurry 5 Bi, Pb, Sb, which are impurity elements dissolved in the neutralized slurry, are added by adding a liquid modifier that reduces trivalent Fe to divalent Fe while suppressing reduction of trivalent arsenic to trivalent arsenic. At least one type of Sn is reduced to obtain an original liquid preparation completion slurry, and after the reduction of the trivalent Fe to divalent Fe, the original liquid preparation completion slurry is filtered to obtain a crystallization original liquid and a neutralized residue. An original liquid preparation step to obtain;
A method for producing scorodite from non-ferrous smelting ash, comprising a crystallization step of producing scorodite from the crystallization liquid.
The second invention is
An alkali is added to the primary leaching end slurry in the primary leaching step, neutralized so that the pH value is 3.5 or less at the maximum, and then the primary leaching step is ended. It is a scorodite manufacturing method from the non-ferrous smelting smoke ash described in the invention.
The third invention is
An acid is added to the non-ferrous smelting ash slurry, and a preliminary leaching step is performed in which the acid-added slurry is leached with a pH value of 0.1 to 1.0, and water is added to the acid-added slurry after the preliminary leaching step. And / or adding a neutralizing agent to reduce the acid concentration of the acid-added slurry, and then subjecting the acid-added slurry to the primary leaching step. This is a method for producing scorodite from non-ferrous smelting ash.
The fourth invention is:
The method for producing scorodite from non-ferrous smelting ash according to the third invention, wherein the preliminary leaching step and the primary leaching step are sequentially performed in one reaction tank.
The fifth invention is:
The first to fourth aspects of the invention are characterized in that the neutralized residue obtained in the original liquid preparation step is repeated in the secondary leaching step to leaching arsenic contained in the neutralized residue. It is a scorodite manufacturing method from the nonferrous smelting ash in any one.
The sixth invention is:
Any of the first to fifth inventions, wherein the secondary leaching solution obtained in the secondary leaching step is repeated to the secondary leaching step to concentrate arsenic contained in the secondary leaching solution. The scorodite manufacturing method from the non-ferrous smelting ash described in 1.
The seventh invention
The scorodite production from the non-ferrous smelting ash according to any one of the first to sixth inventions, wherein the liquid conditioner used in the original liquid preparation step is metallic Fe and / or copper removal electrolytic slime Is the method.
The eighth invention
A Fe source is added to the non-ferrous smelting ash slurry in advance so that the molar ratio of Fe and arsenic (Fe / As molar ratio) dissolved in the secondary leachate is 1 or more. It is a scorodite manufacturing method from the non-ferrous smelting ash according to any one of the first to seventh inventions.
The ninth invention
The scorodite production method from non-ferrous smelting ash according to any one of the first to eighth inventions, wherein the oxidizing agent added in the primary leaching step is hydrogen peroxide.
The tenth invention is
The non-ferrous smelting ash according to any one of the first to ninth inventions, wherein the liquid quality adjusting agent added in the original liquid preparation step is metallic Fe and / or decopperized electrolytic slime and strontium carbonate. Is a method for producing scorodite from
The eleventh invention is
The method for producing scorodite from nonferrous smelting ash according to any one of the first to tenth inventions, wherein the pH adjuster added in the primary leaching step is an alkali containing sulfuric acid or Ca. .
The twelfth invention
In the crystallization step, scorodite production reaction is performed by blowing air or oxygen or a mixed gas of air and oxygen into the crystallization liquid at 80 ° C. or higher under atmospheric pressure, and the slurry after completion of the scorodite production reaction The method for producing scorodite from non-ferrous smelting ash according to any one of the first to eleventh inventions, wherein the scorodite is obtained by filtering the sucrose.
The thirteenth invention
The scorodite obtained in the crystallization step is used as a seed crystal in a scorodite production reaction in the crystallization step of the next batch, according to any one of the first to twelfth inventions, This is a method for producing scorodite from iron smelting ash.

  According to the present invention, a scorodite crystallization liquid having an optimum liquid quality for the production of scorodite can be obtained from non-ferrous smelting ash containing arsenic, Fe, Cu and the like. As a result, it was possible to produce scorodite with excellent elution characteristics and handling properties. In addition, shortening of the treatment process and reduction of the cost of chemicals used were achieved. Furthermore, the shortening of the treatment process reduces the amount of arsenic that is lost outside the process, and the conversion rate of arsenic contained in the non-ferrous smelting ash to scorodite (can be recovered as scorodite. Arsenic ratio) improved.

It is a flowchart which shows the scorodite manufacturing method from nonferrous smelting ash.

  First, as described in the “Means for Solving the Problems” section of this specification, when the non-ferrous smelting ash is slurried with water, almost the same amount of trivalent arsenic as that eluted under strong acidity is present. From this knowledge, the present inventors oxidized the trivalent arsenic to pentavalent arsenic in the optimum pH range, thereby performing the primary leaching step. The idea of being able to put most of the arsenic dissolved in the slurry into the primary leaching residue was explained in detail.

The inventors who have come up with the above-described configuration performed tests I and II below in order to confirm the effect of the configuration and to examine the optimum conditions in the configuration.
In the stirring operations in Tests I and II, two-stage turbine blades with four baffle plates were used, and the reaction temperature was 30 ° C to 40 ° C.

[Test I]
In Test I, the leaching behavior of trivalent arsenic in the primary leaching process was examined using two samples of smelter ash samples A and B generated in the X copper smelter smelter and having different generation dates. .

First, weighed 350 g of each of the two types of smelting ash samples A and B, transferred to 1 liter beakers, added 700 mL of pure water, and stirred vigorously for 30 minutes. A high-concentration A smelting ash slurry was prepared from a smelting ash sample B and a high-concentration B smelting ash slurry.
At the time of preparation of the slurry, a small amount of sampling of the A smelting smoke ash slurry and the B smelting smoke ash slurry was performed. The pH value of the A smelting smoke ash slurry was 1.8, and the pH value of the B smelting smoke ash slurry was 2.1.

Next, 95% sulfuric acid was added to each of the A smelting smoke ash slurry and the B smelting smoke ash slurry, and leaching was performed by vigorous stirring for 30 minutes while maintaining the pH value at 1.0, and a small amount of sampling was performed.
The same operation was repeated, and a small amount of sampling was performed while gradually reducing the pH value of both the A and B smelting ash slurries to 0.5 and then 0.2.
Table 1 shows the analysis results of the sampling sample.

In Table 1, the total arsenic concentration represents the total concentration of pentavalent arsenic and trivalent arsenic.
From the results in Table 1, when water was added to the smelted smoke ash samples A and B to obtain A smelted smoke ash slurry and B smelted smoke ash slurry, most of the trivalent arsenic in the smelted smoke ash samples A and B Was eluted into the A smelted smoke ash slurry and the B smelted smoke ash slurry. The elution level of the trivalent arsenic was found to be almost the same as the elution amount of trivalent arsenic eluted under strong acidity.

[Test II]
In Test II, the influence of the pH value of the smelting ash slurry in the primary leaching process on arsenic and other metal elements was examined.
Specific test conditions and obtained test results will be described.

1. X Purified water added to the smelting smoke ash sample C obtained from a lot different from the smelting smoke ash samples A and B generated in the copper smelter smelting furnace and stirred to obtain a pulp concentration of 400 g / L C smelting ash slurry was prepared.
2. Sulfuric acid was added to the C smelting ash slurry and leached for 1 hour while maintaining a pH value of 0.25 and a temperature of 75 ° C. Next, the C smelted smoke ash slurry was diluted with the same amount of pure water as used in the above slurry preparation, heated again to 75 ° C., and further stirred for 10 minutes to obtain a C leaching slurry. A small amount of the C leaching slurry was sampled. At this time, the pH value of the C leaching slurry was 0.6.
3. A Mg (OH) ₂ aqueous solution having a concentration of 200 g / L was added to the C leaching slurry to adjust the pH value to 1.02. Here, a small amount of the C leaching slurry was sampled.
4). An aqueous solution of Ca (OH) ₂ having a concentration of 200 g / L is added to the C leaching slurry so that the pH value is 1.25, 1.5, 1.75, 2.0, 2. The sample was neutralized stepwise to 5.3.0, and sampling was performed each time. The sampling operation was performed 10 minutes after the C leaching slurry reached the pH value of each stage.
5. 4. above. Each sample sampled in was filtered through an MCE filter with a pore size of 0.2 μm, and the obtained filtrate was used for analysis.
Table 2 shows the analysis results of the sampling sample.

As is clear from Table 2, it was found that each ion coexisting with arsenic in the C leaching slurry gradually decreases as the acidity of the C leaching slurry decreases. For example, when the pH value is increased to 1.5, Bi is reduced to 1/10, Pb is decreased to 1/2, Mo is decreased to 1/3, and Sb and Sn are below the lower limit of analytical quantification (<5 mg / L).
Furthermore, Bi, Pb, and Mo showed the further fall behavior because pH value rose to 2.0.

  From the above results, by the operation of reducing the acidity of the C leaching slurry, most of the ions such as Bi, Pb, Sb, Sn, and Mo coexisting with arsenic in the C leaching slurry are liquid layers of the C leaching neutralization slurry. It was found that precipitation could be removed from the part.

  Further, when the pH value of the C leaching slurry was 1.5 to 3, the pentavalent arsenic in the C leaching slurry became an arsenic compound and showed a behavior of being precipitated from the slurry. As a result, it has been found that most of the arsenic ions dissolved in the C leaching slurry are trivalent arsenic. However, it has been found that the trivalent arsenic also tends to decrease in oxidation efficiency when it has a pH value of 3 or more because it takes a behavior of precipitation from the liquid layer portion.

From the above, when the pH value of the C leaching slurry is in the region of 1.5 to 3, preferably 1.75 to 2.3, it acts as an oxidation inhibitor in the liquid layer portion of the C leaching slurry. It was found that miscellaneous ions do not coexist and there is trivalent arsenic that is subject to oxidation operation.
Based on this knowledge, the present inventors can efficiently and almost completely oxidize trivalent arsenic to pentavalent arsenic by performing the oxidative leaching operation in the primary leaching step in the pH range. I came up with a composition.

  As described above, from the tests I and II, the present inventors found that most of the leachable trivalent arsenic contained in the smelting smoke ash is pentavalent arsenic in the oxidative leaching in the primary leaching step according to the present invention. I came up with a structure that oxidizes efficiently.

  A structure in which most of leachable trivalent arsenic contained in smelting ash is efficiently oxidized to pentavalent arsenic in the oxidative leaching in the primary leaching process according to the present invention, and the results of the above-described tests I and II Thus, the present inventors were able to set operating conditions for oxidative leaching in the primary leaching step described later.

Hereinafter, the form for implementing this invention is demonstrated, referring FIG. 1 which is a flowchart which shows the scorodite manufacturing method from nonferrous smelting smoke ash.
The scorodite production method from non-ferrous smelting ash has a primary leaching step, a secondary leaching step, an original liquid preparation step, a crystallization step, and a preliminary leaching step as necessary.
Hereinafter, the present invention will be described in detail for each step.

[1] Primary leaching step In the primary leaching step according to the present invention, smelting ash is leached, and easily soluble Cu is introduced into the primary leaching solution, and arsenic is introduced into the primary leaching residue, whereby Cu in the smelting ash is obtained. And arsenic.
Specifically, water, process water, or other service water is added to the smelting ash and stirred to produce a high concentration non-ferrous smelting ash slurry with a pulp concentration of 200 g / L to 600 g / L. Then, a pH adjusting agent, an oxidizing agent, and optionally a Fe source are added to the non-ferrous smelting smoke ash slurry to perform pH adjustment and oxidation treatment to perform oxidation leaching to obtain a primary leaching end slurry, and after the oxidation leaching ends The primary leaching end slurry is filtered to obtain a primary leaching solution and a primary leaching residue.
Hereinafter, the effects of adding smelting smoke ash, pH adjusting agent, oxidizing agent, Fe source and Fe source, operation in the primary leaching process, primary leaching residue, and primary leaching solution will be described in this order.

(Smelting ash)
The present invention is applicable to various smelting ash generated from each process of non-ferrous smelting as long as it contains arsenic, Cu, and Fe. In addition to arsenic, the smelting smoke ash contains expensive elements such as Cu and Zn, and various elements derived from ores. Especially, this invention can be effectively applied to the copper smelting ash generated from the smelting process in copper smelting.

(PH adjuster)
There exist an alkali agent and an acid in a pH adjuster. If it is an alkali agent, the alkali containing Ca, such as Ca (OH) ₂ and CaCO ₃ used for general purposes, is preferably mentioned. If it is an acid, the sulfuric acid generally manufactured in the smelter is optimal.

(Oxidant)
As the oxidizing agent, any oxidizing agent capable of oxidizing trivalent arsenic to pentavalent arsenic is applicable. For example, a mixed gas with oxygen using SO ₂ gas generated from a smelting furnace of a smelter is also possible, but hydrogen peroxide is a preferable oxidizing agent because of its good handleability.

(Effect of Fe source addition and Fe source)
Some types of smelting ash have a smaller amount of Fe leached into the secondary leachate than the amount of arsenic leached into the secondary leachate. Thus, when processing smelting smoke ash with a small amount of Fe leached out compared to the amount of arsenic leached into the secondary leachate, it is preferable to replenish the amount of Fe by adding an Fe source ( * 1) in FIG.

The Fe source can be added at any stage as long as it is from the time of preparing the first high-concentration non-ferrous smelting ash slurry to the crystallization step described later. This is because the added Fe source is finally used as Fe for forming scorodite crystals in the crystallization process.
However, by adding the Fe source before the start of the oxidative leaching in the primary leaching process such as the first nonferrous smelting ash slurry preparation or the preliminary leaching process, the added Fe is added during the oxidative leaching in the primary leaching process. However, this is a preferable configuration because it promotes the formation of pentavalent arsenic (entrapment into the primary leaching residue).
The added amount of the Fe source is such that the molar ratio (Fe / As molar ratio) of Fe and arsenic contained in the secondary leaching solution obtained in the secondary leaching step described later is 1.0 to 1.5. It is preferable to carry out.

The Fe source to be added may be an iron salt such as iron sulfate, but may be an iron oxide or an iron compound that can be dissolved in the preliminary leaching step.
In addition, it is also preferable to use, as the Fe source, iron deposits generated during the treatment of wastewater containing arsenic at a non-ferrous smelter. The iron temple contains abundant Fe as compared to arsenic, and further contains valuable metals such as Cu. As a result, when the iron deposit is used as the Fe source, the deposit is easily formed in the primary leaching process, and valuable metals such as Cu contained in the iron deposit move to the primary leaching liquid side. Therefore, not only replenishment of the Fe source but also valuable metals such as Cu are recovered. Furthermore, since arsenic in the iron temple is finally converted to scorodite, it is a preferable configuration from the viewpoint of effective utilization of resources, recovery, and arsenic stabilization.

(Operation in the primary leaching process)
In the primary leaching process according to the present invention, after preparing a high concentration non-ferrous smelting ash slurry, 1.75 to 2.3 which is the most suitable pH range for oxidation of trivalent arsenic dissolved in the slurry, Adjust the pH so that This is because, in the pH range of 1.75 to 2.3, there are few heavy metal elements that adversely affect oxidation, and most of the dissolved arsenic is trivalent arsenic to be oxidized. This is because the oxidation from trivalent arsenic to pentavalent arsenic can be realized.
On the other hand, according to the study by the present inventors, due to the difference in the smelting smoke ash, the non-ferrous smelted smoke ash slurry having a pulp concentration of 500 g / L exhibits an acidity in the pH range of 1.2 to 2.5. Is known.
Therefore, the pH value of the non-ferrous smelting ash slurry is adjusted to the optimum pH value for the above-described trivalent arsenic oxidation by adding a pH adjusting agent (alkaline agent or acid) to the non-ferrous smelting ash slurry. It is preferable.

Add oxidizing agent (for example, hydrogen peroxide solution) to non-ferrous smelting smoke ash slurry after pH adjustment, oxidize trivalent arsenic to pentavalent arsenic, and primary leaching (oxidation leaching), primary leaching A finished slurry was obtained. Then, after the primary leaching is finished, the primary leaching finished slurry is filtered to obtain a primary leaching solution and a primary leaching residue.
For the addition of the oxidizing agent, a method of directly injecting the oxidizing agent into the slurry is preferable from the viewpoint of oxidation efficiency.
The standard for the completion of the oxidant injection and the oxidation reaction is when the liquid potential of the non-ferrous smelting smoke ash slurry shows 550 mV or more, preferably 600 mV or more, based on the Ag / AgCl electrode standard. At that time, it is determined that the primary leaching has been completed.
For example, when hydrogen peroxide is used as the oxidant, the addition and injection time of the hydrogen peroxide to the non-ferrous smelting ash slurry is preferably 10 minutes to 15 minutes. This is because the oxidation efficiency is high according to the addition injection time.

  Even if the reaction temperature in the primary leaching according to the present invention is 30 to 40 ° C., the primary leaching is sufficiently possible. In general, the oxidation of trivalent arsenic with hydrogen peroxide is better as the temperature of the slurry is higher. However, in the primary leaching according to the present invention, it is not necessary to warm to a high temperature.

  By the above operation, trivalent arsenic dissolved in the high concentration non-ferrous smelting ash slurry can be efficiently oxidized to pentavalent arsenic. The pentavalent arsenic oxidized in the pH range related to the primary leaching instantly reacts with Fe, Cu, or Zn in the liquid to form a pentavalent arsenic compound, which is converted into a primary leaching residue. Become. As a result, dissolved arsenic is removed from the liquid layer portion (primary leachate).

  On the other hand, according to the study by the present inventors, even if primary leaching is performed in the above pH range and temperature range and trivalent arsenic is oxidized to pentavalent arsenic, some 5 It was found that valent arsenic may remain in the liquid layer. In such a case, an alkali agent is added to the primary leaching-finished slurry after the completion of the primary leaching, and the pH value is further increased to convert the pentavalent arsenic remaining in the liquid layer portion as a pentavalent arsenic compound. It can be put into the primary leaching residue.

When the pH value of the primary leaching finished slurry is further increased, when the pH value of the slurry reaches 3.4 to 3.5, Cu deposition is accelerated, and separation of arsenic and Cu tends to decrease. . As a result of the decrease in the separation of the arsenic and Cu, there is a concern that the Cu concentration of the secondary leaching liquid obtained in the secondary leaching process described later (the stock solution supplied to the original liquid preparation process) increases.
Therefore, when the pH value of the primary leaching finished slurry is further increased, the pH value is preferably 3.5 or less at the maximum.
However, the pH value at the end of the pH adjustment process can vary depending on the type and properties of the smelting smoke ash and the concentration of the primary leaching end slurry. Therefore, it is considered that the pH value is preferably determined in advance by testing with respect to the smelting smoke ash that is actually treated.

(Primary leach residue)
The primary leaching residue according to the present invention, which is generated in the first batch process, becomes a leaching raw material in a secondary leaching process described later.
On the other hand, the primary leaching residue obtained in the second and subsequent batch processes is mainly used as a neutralizing agent for excessive acid content of the secondary leaching solution in the original liquid preparation step described later. In addition, as will be described later, the primary leaching residue is used as a raw material for secondary leaching when the previously obtained secondary leaching solution is repeated to the secondary leaching step to concentrate the arsenic concentration in the secondary leaching solution. You can also use it. The primary leaching residue added as a neutralizing agent in the original liquid preparation step is recovered as a neutralized residue after completion of the liquid quality adjustment reaction in the original liquid preparation step, and used as a raw material for leaching in the secondary leaching step. Repeated.

(Primary leachate)
In the primary leaching process according to the present invention, most of the readily soluble Cu could be leached to the primary leaching liquid side. The Cu leaching rate ranged from 70 to 80%. As the primary leaching solution, a liquid having a Cu concentration of 30 to 60 g / L and an arsenic concentration of 0.1 g / L or less was obtained.
The primary leachate can be separately sent to a Cu recovery step, and Cu contained in the primary leachate can be recovered as electrolytic copper by, for example, the SX / EW (solvent extraction / electrolytic extraction) method. In addition, since the extraction residue after solvent extraction of the primary leachate contains Zn or the like, the Zn can be recovered as zinc hydroxide by a neutralization treatment and supplied as a Zn raw material of a zinc smelter. I can do it.

[2] Preliminary leaching process Cu, Zn, Cd and the like contained in the smelting smoke ash are easily leached in the primary leaching process described above. As a result, in the secondary leaching step described later, the elements are not so leached.
However, according to the study by the present inventors, due to differences in smelting smoke ash (difference in smelting furnace type), the elements such as Cu, Zn, Cd are not sufficiently leached in the primary leaching process, It has been found that in the secondary leaching process, there may be a large amount of leaching into the secondary leaching solution. In this case, a large amount of these elements leached into the secondary leaching solution is contained in the crystallization original solution through the original solution preparation step. Then, in the crystallization process to be described later, the viscosity of the crystallization liquid containing a large amount of these elements may increase and hinder the reaction. In particular, Cd is an element subject to elution regulation, and there is a concern that the Cd elution value exceeds the regulation standard value in the obtained scorodite. Therefore, in such a case, it is preferable to take measures for leaching elements such as Cu, Zn, Cd and the like in the primary leaching step and shifting to the primary leaching solution.
As a means for transferring elements such as Cu, Zn, Cd and the like to the primary leaching solution, it is effective to perform a preliminary leaching step.

That is, the preliminary leaching step is performed prior to the above-described primary leaching step as necessary (* 2 in FIG. 1).
In the preliminary leaching step, an acid is added to the nonferrous smelting ash slurry, the pH value of the acid addition slurry is set to 0.1 or more and 1.0 or less, and the temperature of the acid addition slurry is further heated to 50 ° C. or more. The leaching is performed under the above conditions. In addition, as an acid to add, a sulfuric acid is suitable.

Preliminary leaching conditions such as optimum pH value and temperature are preferably determined by examining each smelting ash generated at each smelter to be treated.
However, according to the study by the present inventors, if the pH value of the slurry in the preliminary leaching is 1.0 or less, about 70 to 90% by mass of Cu to be leached is leached and should be leached. About 80 to 90% by mass of Zn and Cd are leached. Furthermore, it has been found that when the pH value of the slurry is 0.2 to 0.3, leaching of Cu, Zn and Cd to be leached is almost completed. On the other hand, when the pH value of the slurry is 0.1 or more, the chemical cost of the acid to be added is suppressed.
As for the temperature of the slurry, in the range between room temperature (25 ° C.) and 50 ° C., the leaching rate of Cu, Zn, Cd, etc. is remarkably improved as the temperature rises, and the leaching rate is improved at 50 ° C. or higher. It has been found that the degree of gradual decrease.
Therefore, the slurry temperature at the time of leaching is preferably 50 ° C. or higher, and it is preferable to set the upper limit at about 80 ° C. in consideration of equipment specifications during actual operation.

The leaching reaction time in the preliminary leaching is required to be 30 minutes or more from the time point when the above leaching conditions are satisfied, and the target leaching is almost achieved in one hour.
At the end of the preliminary leaching, the slurry obtained is hydrated to the same volume as that of the slurry to reduce the slurry concentration and the acid concentration, and then subjected to the primary leaching step described above.
The purpose of the water addition is to suppress an increase in the viscosity of the non-ferrous smelting ash slurry during the addition of the alkaline agent in the primary leaching step.
Note that the preliminary leaching step and the primary leaching step can be sequentially performed in one reaction tank. It is also possible to perform the preliminary leaching process in one reaction tank, transfer the reaction-finished slurry to the second reaction tank, and continuously perform the primary leaching process. Of course, the preliminary leaching process and the primary leaching process may be performed in a multi-stage process (for example, a two-stage continuous process).

[3] Secondary leaching step The secondary leaching step according to the present invention is performed by supplying water to the primary leaching residue obtained in the above-described primary leaching step or the neutralized residue obtained in the original liquid preparation step described later. The secondary leaching solution obtained earlier is added to form a slurry, and an acid such as sulfuric acid is added to the slurry to perform acidic leaching to obtain a secondary leaching finished slurry. Then, after the acidic leaching is finished, the secondary leaching finished slurry is filtered to obtain a secondary leaching solution containing arsenic, Fe and the like and a secondary leaching residue.
In carrying out the secondary leaching process, in the initial batch process,
As the leaching target, the primary leaching residue obtained in the primary leaching step described above is used (* 3 in FIG. 1). In the second and subsequent batch processing, the neutralized residue obtained mainly in the original liquid preparation step described later is a target for leaching.
In addition, when the secondary leaching solution is repeated to the secondary leaching step and the arsenic concentration in the secondary leaching solution is concentrated, the primary leaching residue can be used as a raw material in addition to the neutralized residue.
In addition, in the method using decoppered electrolytic slime as the liquid quality adjusting agent described later in the original liquid preparation step, the excess amount of the decoppered electrolytic slime may be contained in the neutralized residue without being reacted. Therefore, an oxidation leaching stage for blowing an oxidizing gas at the end of the leaching reaction in the secondary leaching step can be provided.
Hereinafter, the operation in the secondary leaching step, the secondary leaching solution, and the secondary leaching residue will be described in this order.

(Operation in secondary leaching process)
As described above, in the secondary leaching process according to the present invention, the primary leaching residue is mainly used in the first batch, and the neutralized residue obtained in the original liquid preparation process described later is mainly used in the second and subsequent batches. Target leaching.
The pulp concentration (PD: g / L) of the primary leaching residue slurry or neutralized residue slurry to be leached is determined by the amount of secondary leaching liquid generated in the primary liquid preparation step described below. Adjust so that neutralization reaction by adding leach residue can be secured.

By adding an acid to the primary leaching residue slurry or neutralized residue slurry that is the leaching target, the pH value of the leaching target slurry is set within the range of 0.1 to 0.5. When the preliminary leaching described above is performed, the value is lower than the pH value of the slurry at the time of the preliminary leaching. As the acid to be added, sulfuric acid is suitable.
And the said leaching object slurry is heated, temperature is 50 degreeC or more, Preferably it is about 80 degreeC, the acidic leaching conditions are satisfied, and the secondary leaching completion slurry is obtained.

The acid leaching reaction time in the secondary leaching is required to be 30 minutes or more from the time when the above-described leaching conditions are satisfied, and the target leaching is almost achieved in 1 hour.
After the acidic leaching is finished, the secondary leaching finished slurry is subjected to solid-liquid separation to obtain a secondary leaching solution and a secondary leaching residue.

(Secondary leachate)
The obtained secondary leaching solution is a solution mainly containing arsenic and Fe.
The secondary leaching liquid is sent to the original liquid preparation process which is the next process.
On the other hand, it is preferable that the secondary leaching solution is repeated in the secondary leaching step and used as water for the secondary leaching step, whereby the arsenic concentration in the secondary leaching solution can be concentrated. This is because arsenic in the secondary leachate is pentavalent arsenic having a high solubility, so that arsenic can be concentrated to a considerably high concentration. However, considering the viscosity of the crystallization reaction slurry during the reaction in the crystallization process described later, the arsenic concentration in the secondary leachate sent to the original liquid preparation process, which is the next process, is 20 to 40 g / L. It is preferable.

(Secondary leach residue)
The obtained secondary leaching residue contains elements such as Pb, Bi, Sb, and Sn in addition to the Cu content not leached in the secondary leaching. Therefore, it is possible to supply the secondary residue as a copper raw material for a copper smelter, but it can also be supplied as a lead smelting raw material. This is because the lead smelter has a recovery process for Cu, Bi, Sb, and Sn in addition to Pb recovery. Whether the secondary leaching residue is supplied as a raw material of a copper smelter or a lead smelter depends on whether the copper smelter is in the process of Pb, Bi, Sb, Sn, etc. Judging from economic efficiency.

[4] Original liquid preparation process In the original liquid preparation process according to the present invention, the primary leaching residue is added to the secondary leaching liquid described above to neutralize the excess acid content contained in the secondary leaching liquid. A sum slurry is obtained. Subsequently, by adding a liquid quality adjusting agent described later to the neutralized slurry, trivalent Fe is reduced to divalent Fe while suppressing reduction of pentavalent arsenic dissolved in the neutralized slurry to trivalent arsenic. . Then, by reducing trivalent Fe to divalent Fe, an impurity element (dissolved heavy metal) that adversely affects the scorodite crystallization reaction is removed until a low concentration is obtained, thereby obtaining an original liquid preparation finished slurry. And after completion | finish of the reduction | restoration of the said trivalent Fe to bivalent Fe, it is the process of filtering the said original solution preparation completion | finish slurry, and obtaining a crystallization original solution and a neutralization residue.

More specifically, by adding a liquid quality adjusting agent described later to the neutralized slurry, it is dissolved in the neutralized slurry while suppressing reduction of pentavalent arsenic dissolved in the neutralized slurry to trivalent arsenic. In this process, trivalent Fe is reduced to divalent Fe, and impurity elements such as Bi, Sb, Pb, and Sn coexisting in the neutralized slurry are transferred to the neutralized precipitate. And the original liquid preparation completion | finish slurry in which content of trivalent Fe and the said impurity element was reduced is obtained. Then, after the reduction of the trivalent Fe to the divalent Fe is completed, the original liquid preparation completion slurry is filtered to obtain a crystallization original liquid that can be directly supplied to the scorodite crystallization reaction.
Hereinafter, the crystallization original solution, the effect of the liquid quality adjusting agent that made it possible to obtain the crystallization original solution, the liquid quality adjusting agent, the operation in the original liquid preparation process, the crystallization original solution, and the neutralized residue will be described in this order. To do.

(Crystallization liquid)
The crystallization liquid is a solution containing pentavalent arsenic and divalent Fe.
According to the study by the present inventors, when trivalent Fe and divalent Fe are contained in the crystallization liquid, the crystallization reaction with pentavalent arsenic by the trivalent Fe is performed at the initial stage of the crystallization reaction. We know the phenomenon that the scorodite that progresses rapidly and the resulting scorodite becomes finer.
Further, according to the study by the present inventors, in the above-described secondary leaching step, when leaching is performed at a pulp concentration at which the arsenic concentration in the secondary leaching solution is 20 g / L, the impurity element concentration is Bi = 2 at the maximum. , 650 mg / L, Sb = 110 mg / L, Pb = 270 mg / L, and Sn = 210 mg / L. Further, it has been found that many of these impurity elements are deposited during the scorodite crystallization reaction, which causes finer scorodite crystal particles and deteriorates the elution characteristics of the scorodite itself.

From the above findings, the preferred liquid quality of the crystallization liquid is
(1) Most of Fe (specifically, 90% or more) contained in the crystallization liquid is divalent Fe.
(2) The impurity concentration contained in the crystallization liquid is low. Specifically, the total value of (Bi + Pb + Sb + Sn) is less than 500 mg / L, and Pb is less than 100 mg / L. The impurity concentration is preferably as low as possible.
(3) It is preferable that the proportion of pentavalent arsenic is large in the arsenic contained in the crystallization liquid. Specifically, the proportion of pentavalent arsenic in the total arsenic of pentavalent arsenic and trivalent arsenic is preferably 70% or more. This is because the formation reaction of scorodite is due to pentavalent arsenic and that the trivalent arsenic is prevented from remaining without being oxidized at the end of the crystallization reaction, thereby improving the elution characteristics of the obtained scorodite. This is because it can be secured.

(Addition effect of liquid modifier)
In preparing the crystallization liquid, the present inventors have made various investigations on liquid quality adjusting agents that enable reduction of trivalent Fe to divalent Fe while suppressing reduction of pentavalent arsenic to trivalent arsenic. went. Then, in the process of studying, an appropriate liquid quality adjusting agent is added to the secondary leaching solution, and trivalent Fe is reduced to divalent Fe to reduce the liquid potential of the solution, so that Bi, Pb, The inventors have discovered an epoch-making phenomenon that impurities such as Sb and Sn become precipitates and can be removed from the liquid.

As a result of analyzing the precipitate by X-ray diffraction, the present inventors have identified that Bi is precipitated as bismuth arsenate (BiAsO ₄ ). From the analysis results, it is considered that impurities such as Pb, Sb, Sn other than Bi were similarly precipitated and removed as arsenic acid compounds.

The present inventors presume the phenomenon that impurities such as Bi, Pb, Sb and Sn become precipitates and can be removed from the liquid as follows.
Bi forms bismuth arsenate, which is an arsenate compound, in a solution containing pentavalent arsenic ions (arsenate ions) at a high concentration, so that Bi cannot be dissolved at a g / L order. That is, it is considered that not only Bi but also other heavy metals are dissolved by forming a heavy metal-arsenic acid complex ion and a part or most of the dissolved amount in the same manner as Bi.
These heavy metals-arsenate complex ions are presumed to be stably present when trivalent Fe is contained in the liquid and the liquid potential is high.
However, when an appropriate liquid conditioner is added to the liquid and the trivalent Fe is reduced to divalent Fe and the liquid potential decreases, the heavy metal-arsenate complex ion breaks and the heavy metal-arsenate compound is reduced. Presumed to form and deposit. However, the actual reaction mechanism is currently unknown.

  The deposition of the heavy metal-arsenic acid compound proceeds even when the reduction rate of trivalent Fe to divalent Fe in the solution is about 80%. However, in order to proceed more reliably, the reduction rate of trivalent Fe to divalent Fe is preferably 90 to 100%.

(Liquid quality regulator)
Examples of the liquid quality adjusting agent include metal Fe, copper removal electrolytic slime, metal Cu, zinc sulfide (ZnS), zinc concentrate and the like. Among these, metal Fe is preferable because of its high reactivity.
In addition, the copper removal electrolytic slime is a liquid purification process (a process in which impurities such as arsenic accumulated in the copper electrolytic solution are collected by electrolytic collection) performed in a copper electrolytic refining factory. Cu and arsenic form a copper arsenide form, etc. It is a deposit generated by electrolytic deposition as a mud-like metal. And the said liquid purification process is the method generally employ | adopted in the copper electrolytic refinery factory. Therefore, the decoppered electrolytic slime is a deposit that is inevitably generated to ensure the quality of electrolytic copper, and it can be obtained at no cost if it is a smelter that owns a copper electrolytic plant. Is advantageous.
Here, the copper removal electrolytic slime is one of the three major arsenic-containing intermediate products in copper smelting, along with the sulfide deposits generated in the treatment of smelter smoke ash and sulfuric acid factory effluent. That is, by using the decoppered electrolytic slime as a liquid conditioner in the present invention, arsenic contained in two main arsenic-containing intermediate products, smelting smoke ash and decoppered electrolytic slime, are simultaneously processed at once. It is possible to convert to a stable scorodite.

(Addition of liquid modifier)
The operation for adding the liquid quality adjusting agent will be described for each main liquid quality adjusting agent.
(1) When using metallic iron (Fe) and metallic copper (Cu) The amount of the regulator added is only the amount necessary for the reduction of trivalent Fe dissolved in the neutralized slurry to divalent Fe. good. Excessive addition is preferably avoided because pentavalent arsenic dissolved in the neutralized slurry is reduced to trivalent arsenic. Therefore, it is important to confirm the reactivity of the regulator in advance. In addition, Fe powder is preferable as metallic iron, and Cu powder is preferable as metallic copper from the viewpoints of reactivity and handling properties.

On the other hand, when inexpensive Fe scrap or Cu scrap is used as metallic iron or metallic copper, it is preferable to provide a separate dedicated reaction facility. Specifically, a column filled with Fe scrap or Cu scrap, or a Trommel classifier charged with the scraps in multiple stages and passing the neutralized slurry to convert trivalent Fe into divalent Fe. Reduction is achieved.
The reaction temperature is not particularly limited and may be room temperature, but the higher the temperature (50 to 70 ° C.), the more the reactivity is improved.
The reaction time is determined by the shape of metal iron and metal copper to be used (powder shape, scrap situation, etc.) and reaction equipment. The reaction time is set to a condition in which 90 to 100% of trivalent Fe contained in the neutralized slurry is reduced to divalent Fe.

  In the description of the primary leaching step, it has been explained that the Fe source is added when the Fe content in the adjustment source solution is less than the amount necessary to produce the arsenic contained as scorodite. However, by selecting metal Fe as the liquid quality adjusting agent, it is also possible to supply a deficient amount of Fe while reducing the amount of iron source added in the primary leaching step.

(2) When using a copper removal electrolytic slime The addition amount of the copper removal electrolytic slime as a liquid conditioner is the same as that of the metal Fe described in (1), and the trivalent Fe dissolved in the neutralized slurry. Only the amount required for reduction to divalent Fe is sufficient. Specifically, it is an amount for reducing 90 to 100% of the dissolved trivalent Fe in the neutralized slurry to divalent Fe.
In the case of excessive addition in the case where the copper removal electrolytic slime is applied as the liquid quality adjusting agent, the copper removal electrolytic slime enters the neutralized residue without being reacted and is supplied to the secondary leaching step. Therefore, in the secondary leaching step, it is effective to perform oxidative leaching by aeration or the like at the end of the leaching reaction in order to dissolve the decoppered electrolytic slime.

The reaction temperature is the same as that of metallic iron (Fe) and metallic copper (Cu) described in (1) and is not particularly limited, and may be room temperature, but the higher the temperature (50 to 70 ° C.), the more reactive improves.
The reaction time varies depending on the stirring strength of the reaction tank and the reaction temperature, but is set to a condition in which 90 to 100% of the trivalent Fe contained in the neutralized slurry is reduced to divalent Fe.

  When copper-free electrolytic slime is used as a liquid quality adjusting agent, trivalent arsenic is eluted along with Cu during the liquid quality adjusting reaction, and the trivalent arsenic concentration increases. Therefore, the added amount of copper removal electrolytic slime is adjusted so that the proportion of trivalent arsenic in the total amount of pentavalent arsenic and trivalent arsenic at the end of the liquid quality adjustment reaction does not exceed 30%. It is preferable. Here, in the liquid quality adjustment using only the copper removal electrolytic slime, it is difficult to adjust the ratio of trivalent arsenic in the total amount of pentavalent arsenic and trivalent arsenic so as not to exceed 30%. In this case, it is preferable to use in combination with other liquid quality adjusting agents such as metallic iron (Fe).

(3) When using strontium carbonate together In the above (1) and (2), the case where metallic iron (Fe), metallic copper (Cu), and a copper removal electrolytic slime are used as a liquid quality adjusting agent was demonstrated. The same applies when zinc sulfide or zinc concentrate is used as the liquid quality adjusting agent.
However, when the content of Pb in the secondary leachate is high, or when processing a secondary leachate that is likely to elute Pb, the amount of Pb elution from the primary leach residue used as a neutralizing agent for excess acid content is When there are many cases, or when these cases overlap, it is effective to add strontium carbonate in combination in order to avoid a situation where the liquid quality adjusting agent is excessively added.

The addition of strontium carbonate can also be performed on a neutralized slurry in which a large amount of solid content is suspended. The effect of the addition of strontium carbonate to the neutralized slurry in which a large amount of solid is suspended is not inferior to the effect when added to the filtrate obtained by removing the solid from the neutralized slurry, and is an effective method. is there.
The timing of adding strontium carbonate may be as follows. First, a liquid quality adjusting agent may be added to the neutralized slurry and strontium carbonate may be added after the reaction is completed, but the liquid quality adjusting agent and strontium carbonate are added simultaneously. This shows a behavior in which the reactivity is further improved.
For example, when 102 mg / L of Pb remains in a crystallization liquid prepared using metallic iron (Fe powder) as a liquid quality adjusting agent, strontium carbonate is added to the liquid quality adjustment reaction completed slurry by the addition of the Fe powder. Add to the slurry at a concentration of 0.4 g / L and stir for 1 hour. Then, it discovered that Pb density | concentration fell to 40 mg / L. On the other hand, when the Fe powder and strontium carbonate were added simultaneously and reacted for 1 hour, it was found that the Pb concentration decreased to 15 mg / L.
Regarding the reason for the behavior that improves the reactivity, it is considered that the neutralization slurry gradually destroys the Pb-arsenate complex ions and partially regenerates immediately after the addition of the liquid quality modifier, but strontium carbonate coexists at the same time. Therefore, it is presumed that the regeneration of the Pb-arsenate complex ion is prevented and the reactivity of Pb removal is improved. However, the actual reaction mechanism is currently unknown. In any case, the simultaneous addition method of the liquid quality adjusting agent and strontium carbonate is considered to be effective from the viewpoint of reducing the amount of strontium carbonate added and reducing the reaction time.

The combined addition amount of strontium carbonate may be several tens to several hundreds g per 1 m ³ of the neutralized slurry, but the addition amount is preferably determined in advance.
By the combined addition of the strontium carbonate, Pb in the neutralized slurry can be reliably and stably finished within the reference value (<100 mg / L).

(Operation in the original liquid preparation process)
The original liquid preparation process according to the present invention comprises two stages.
In the first stage, the primary leaching residue is added to the above-mentioned secondary leaching solution to neutralize excess acid content, and the pH of the neutralized slurry is adjusted to 0.2 to 0.4.
In the second stage, which is sequentially performed after the first stage, a predetermined amount of the above-described liquid quality adjusting agent is added to the neutralized slurry that has finished the reaction in the first stage, and reduction of trivalent Fe to divalent Fe is achieved. And the purified liquid by the deposition of impurities, and finally the pH value is adjusted to 0.4 to 0.9 to obtain the original liquid preparation finished slurry.

When a metallic modifier such as metallic Fe or decopperized electrolytic slime is used as the liquid modifier, the pH value of the neutralized slurry rises naturally during the reaction, so at the end of the reaction without adding alkali. The value is within the target pH range. The reaction is completed within 20 minutes to 1 hour, depending on the reactivity of the liquid quality adjusting agent itself and the reaction equipment.
The reaction temperature may be room temperature. However, when metallic iron (Fe), metallic copper (Cu), and copper removal electrolytic slime are used as the liquid quality adjusting agent, an exothermic reaction is involved, so that the final liquid temperature is 40. May rise to ~ 50 ° C.
The original liquid preparation completion slurry obtained by the above operation and having finished the final reaction is subjected to filtration to obtain a crystallization original liquid and a neutralized residue.

(Crystallization liquid)
The obtained crystallization original solution is an arsenic solution in which impurity elements that adversely affect the properties of scorodite are reduced, and almost 100% of Fe contained is adjusted to be divalent Fe. Therefore, the crystallization liquid can be directly subjected to a scorodite crystallization production reaction.

(Neutralization temple)
The neutralized precipitate recovered in the original solution preparation process contains soluble arsenic. Therefore, it is preferable that the neutralized precipitate is sent to the secondary leaching step to complete the arsenic leaching by high-temperature strong acid leaching.

[5] Crystallization Step The crystallization step according to the present invention is a step of converting arsenic in the crystallization raw solution obtained in the original solution preparation step into scorodite crystals to obtain scorodite and a solution after crystallization. .
Hereinafter, the operation in the crystallization step, scorodite, and the solution after crystallization will be described in this order.

(Operation in the crystallization process)
Specifically, the slurry after completion of the scorodite formation reaction is performed by blowing air or oxygen or a mixed gas of air and oxygen into the original liquid at an atmospheric pressure of 80 ° C. or higher, preferably 95 ° C. and constant temperature. To get. In addition, since Cu coexists in the crystallization liquid, and the element functions as an oxidation catalyst, air can be used in the first half of the gas blowing and oxygen can be used in the second half.
In a reaction time of 6 to 9 hours, scorodite having excellent elution characteristics is produced. By filtering the slurry after completion of the production reaction, a scorodite and a liquid after crystallization are obtained.

(Scorodite)
The obtained scorodite is most stable at a pH value of 3 to 5, and thus can be stably stored in an air atmosphere without being affected by acid rain or the like.
That is, the scorodite is the most excellent substance for long-term storage of arsenic.

(Liquid after crystallization)
The resulting post-crystallization solution contains 0.5 g / L to 1.5 g / L of arsenic, 10 g / L to 15 g / L of Fe, several g / L to 20 g / L of Cu, and several g / L of Zn. Since it is contained in L, it is sent to the wastewater treatment process to separate and recover these metals.
For example, as an example of the wastewater treatment process, first, calcium carbonate is added, neutralization is performed with a pH value of around 1, and gypsum is recovered. The collected gypsum is washed with water to remove the adhering liquid, and then collected as washed gypsum. Then, calcium carbonate is added to neutralize the pH value to around 3.5 and collect the arsenic-containing residue. The recovered arsenic deposit can be repeatedly collected into the smelting furnace and again as smoke ash. On the other hand, since the liquid after the arsenic is recovered contains Cu, Fe, Zn, etc., it can be supplied to the copper recovery process and can be repeated as water for the primary leaching process. That is, various configurations are possible.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
[Smelting ash]
Table 3 shows the composition of the smelting smoke ash to be treated in this example. The smoke ash according to Example 1 was determined to be smoke ash that requires preliminary leaching treatment because contained Cu, Cd, and the like exhibited poorly soluble behavior.

[1] Primary leaching process After adding 200 L of water to 200 kg of smoke ash to make a slurry, 75% sulfuric acid was added to adjust the pH value to 0.10 (50 ° C.), and leaching was performed for 1 hour. After completion of the reaction, 26.1 kg of polyferric sulfate solution (Fe solution containing 11% by mass or more of trivalent Fe) is added to the slurry as an Fe source, and after supplementing the lack of Fe, 200 L of water is added. Thus, the slurry concentration was lowered. Subsequently, 200 mg / L of Ca (OH) ₂ milk was added to adjust the pH value to 2.2 (40 ° C.). Thereafter, 35% hydrogen peroxide solution was added to the slurry, the liquid potential of the slurry was set to exceed 550 mV (vs; Ag / AgCl), and oxidation reaction of trivalent arsenic and divalent Fe was performed.
The amount of 35% hydrogen peroxide solution added was 5.9 kg, and the addition time was about 10 minutes.
The slurry after the oxidation reaction was subjected to solid-liquid separation using a filter press, and the primary leachate was collected. Further, the residue in the filter press was washed with water, and the primary leaching residue and the primary washing water were collected.
The operation of the primary leaching step was performed a total of 6 times, and a total of 1,601 kg · wet (average moisture value of 35.8 mass%) of the primary leaching residue was collected. The recovered primary leaching residue was subjected to a test after the secondary leaching step.
Table 4 shows the average composition of the generated primary leaching solution, and Table 5 shows the average composition of the recovered primary leaching residue.

[3 (1)] Secondary leaching process (first batch)
In the secondary leaching process according to the first batch according to Example 1, 140 L of water is added to the primary leaching residue 220 kg · wet obtained in the primary leaching process to form a slurry, and the pH value is obtained by adding 75% sulfuric acid. Was adjusted to 0.11 (75 ° C.), and the temperature was maintained while leaching for 1 hour while directly blowing saturated steam at a pressure of 0.5 MPa. The leached slurry was subjected to solid-liquid separation with a filter press to recover the secondary leaching solution, and further washed with water, and then the secondary leaching residue and secondary washing water were recovered.

[4 (1)] Original solution preparation process (first batch)
In the original liquid preparation process according to the first batch, the secondary leachate obtained in the secondary leaching process according to the first batch was used. The primary leaching residue was added to 270 L of the secondary leaching solution, and the mixture was stirred for 40 minutes to neutralize excess acid, and the pH value of the neutralized slurry was adjusted to 0.24 (29 ° C.). At this time, the liquid potential of the neutralized slurry was 445 mV (vs; Ag / AgCl electrode).
Subsequently, 6.7 kg of industrial Fe powder was added as a liquid quality adjusting agent to the neutralized slurry and reacted for 30 minutes to complete the original liquid preparation step according to the first batch. The slurry at this point had a pH value of 0.69 (40 ° C.) and a liquid potential of 180 mV (vs; Ag / AgCl).
The slurry after the original liquid preparation step was subjected to solid-liquid separation by a filter press to recover the crystallization original liquid, and further, the filter press was washed with water to collect the neutralized residue and the washed water with water.

[3 (2)] Secondary leaching process (first half of second batch)
In the first half of the secondary leaching process according to the second batch, secondary leaching was performed on the neutralized residue obtained in the original liquid preparation process according to the first batch. That is, after measuring 100 kg · wet of the neutralized residue (water content: 24% by mass), adding 90 L of water to make a slurry, and adjusting the pH value to 0.10 (75 ° C.) by adding 75% sulfuric acid. The temperature was maintained while directly blowing saturated steam at a pressure of 0.5 MPa, and leaching was performed for 1 hour.
The slurry after leaching was subjected to solid-liquid separation by a filter press, and the secondary leaching liquid according to the first half was collected, and after passing through the filter press, the secondary leaching residue and the secondary washing water according to the first half were collected. . The recovered secondary leaching residue was 83 kg · wet (water content 23 mass%), containing 2.8 mass% arsenic, 2.6 mass% Cu, and 3.2 mass% Fe. It was. The secondary leaching residue is obtained when the material to be leached in the secondary leaching process described above becomes a neutralized residue produced in the original liquid preparation process, that is, when the process is in a steady state. is there.

[3 (2)] Secondary leaching process (second half of the second batch)
In the second half of the secondary leaching process according to the second batch, the secondary leaching solution 160L obtained in the first half is repeatedly used as the water to the secondary leaching process, and the primary leaching residue 190 kg · wet is added, and further 75% After adjusting the pH value to 0.16 (75 ° C.) by adding sulfuric acid, the temperature was maintained while saturating steam with a pressure of 0.5 MPa directly, and leaching was performed for 1 hour. The slurry after the secondary leaching is separated into solid and liquid by a filter press, and the secondary leaching liquid in the latter half is collected, washed with water through the filter press, and then the secondary leaching residue and the secondary washing water in the latter half. Was recovered. The arsenic concentration in the secondary leachate was 23.8 g / L.

[4 (2)] Original solution preparation process (second batch)
In the original liquid preparation process according to the second batch, the secondary leaching liquid obtained in the latter half of the secondary leaching process was used. The primary leaching residue was added to 255 L of the secondary leaching solution, and the mixture was stirred for 40 minutes to neutralize excess acid, and the pH value of the neutralized slurry was adjusted to 0.21 (37 ° C.). At this time, the liquid potential of the slurry was 439 mV (vs; Ag / AgCl electrode). A small amount of sampling was performed here. From the analysis results after the sample, Pb was dissolved in 270 mg / L, Bi was dissolved in 910 mg / L, and divalent Fe was the total Fe concentration (total concentration of divalent Fe and trivalent Fe). It was found that the percentage of the total was 41%.
Subsequently, 5.0 kg of industrial Fe powder was added and allowed to react for 35 minutes to complete the reduction purification reaction. The slurry at this point had a pH value of 0.41 (41 ° C.) and a liquid potential of 230 mV (vs; Ag / AgCl).
The slurry after the original liquid preparation step according to the second batch is subjected to solid-liquid separation by a filter press to recover the crystallization original liquid according to the second batch, and further washed with water through the filter press. The neutralized residue and water-washing water related to the batch were collected.
Table 6 shows the composition of the obtained crystallization liquid. The ratio of divalent Fe in the crystallization liquid to the total Fe concentration (total concentration of divalent Fe and trivalent Fe) was 92%.

[5] Crystallization Step Here, an example of the crystallization step of crystallization source solution to scorodite using the crystallization source solution produced after the step enters a steady state will be shown.
In the crystallization step, 287 L of the crystallization original solution obtained in the original solution preparation step related to the second batch was filled in a tank having a stirring means and heated to 95 ° C.
When the liquid temperature reached 95 ° C., the reaction was started, and oxygen gas was blown from the bottom of the tank at a rate of 30 L / min.
Here, the stirring was performed at a strength at which gas-liquid mixing was sufficiently ensured, and the reaction was performed up to the 9-hour time point under the conditions. The pH value at the end of the crystallization step was 0.23 (95 ° C.), and the arsenic concentration in the solution after crystallization was 0.70 g / L.

The slurry after the crystallization step was subjected to solid-liquid separation with a filter press to obtain scorodite. The obtained scorodite was repulped with 600 L of water for 1 hour using a washing tank.
The washed scorodite was subjected to solid-liquid separation with a filter press, and the washed scorodite was recovered.

  The scorodite recovered by the above operation was 32.2 kg · wet (water content 20.5% by mass). Then, a part of the collected scorodite was subjected to a dissolution test and a composition analysis.

  The obtained scorodite according to Example 1 had an average particle size of 3.7 μm and good filterability. Furthermore, as a result of subjecting the scorodite to a TCLP elution test determined by the US Environmental Protection Agency (EPA), all the heavy metals specified as well as arsenic satisfied the standard value.

  Table 7 shows the average particle diameter, composition, and moisture content of the obtained scorodite, and Table 8 shows the standard values of the TCLP dissolution test and the evaluation results of the scorodite dissolution test according to Example 1.

  In the distribution of arsenic when the process flow reaches a steady state when the amount of arsenic contained in the smelting ash and the amount of Cu are 100%, 62.3% of the arsenic in the smelting ash is scorodite. It was found to be recoverable. This means that about 96% of the leachable arsenic arsenic can be converted to scorodite.

  Furthermore, the distribution of Cu to the primary leaching solution was 74.3% in Example 1, which was improved by about 30 points compared to the case where preliminary leaching was not performed. That is, it is because the leaching rate of Cu in the primary leaching process has been improved, and it is considered that the adoption of preliminary leaching greatly contributed to this. On the other hand, 74% of Cu in the smelting smoke ash can be recovered as a primary leachate with a high Cu concentration.

(Example 2)
In Example 2, the liquid quality adjusting agent was replaced by Fe copper removal slime in the original liquid preparation step. Table 9 shows the composition of the copper removal electrolytic slime. In addition, the water content value of the said copper removal electrolytic slime was 9.7 mass%.

[1] Primary leaching step The same operation as in Example 1 was performed using the same smoke ash as in Example 1.

[3] Secondary leaching process (first batch)
In the secondary leaching step according to the first batch according to Example 2, 140 L of water is added to the primary residue 220 kg · wet obtained in the primary leaching step to form a slurry, and 75% sulfuric acid is added to adjust the pH value to 0. After adjusting to 21 (73 ° C.), the temperature was maintained while saturating steam with a pressure of 0.5 MPa directly, and leaching was performed for 1 hour. The leached slurry was subjected to solid-liquid separation with a filter press to recover the secondary leaching solution, and further washed with water, and then the secondary leaching residue and secondary washing water were recovered.

[4] Original solution preparation process (first batch)
In the original liquid preparation process according to the first batch, the secondary leaching liquid obtained in the secondary leaching process was used. The primary leaching residue was added to 280 L of the secondary leaching solution and stirred for 50 minutes to neutralize excess acid, and the pH value of the neutralized slurry was adjusted to 0.24 (27 ° C.). At this time, the liquid potential of the slurry was 451 mV (vs; Ag / AgCl). A small amount was sampled here. From the analysis results after the sample, Pb was dissolved in 285 mg / L, Bi was dissolved in 1,010 mg / L, and the divalent Fe was the total Fe concentration (total of divalent Fe and trivalent Fe). It was found that the ratio to the (concentration) was 25%.
Subsequently, 8.0 kg · wet of copper removal electrolytic slime was added to the neutralized slurry and reacted for 25 minutes to complete the original liquid preparation step. At this time, the pH value of the slurry was 0.39 (28 ° C.), and the liquid potential was 264 mV (vs; Ag / AgCl).
The slurry after the reaction was subjected to solid-liquid separation using a filter press to recover the crystallization original solution, and further washed with water, and then the neutralized residue and water-washed water were collected.
Table 10 shows the composition of the obtained crystallization liquid. The ratio of divalent Fe in the crystallization liquid to the total Fe concentration (total concentration of divalent Fe and trivalent Fe) was almost 100%.

[3 (2)] Secondary leaching process (first half of second batch)
In the first half of the secondary leaching process according to the second batch, secondary leaching was performed on the neutralized residue obtained in the preparation of the original liquid according to the first batch. That is, after measuring 110 kg · wet (water content 28% by mass) of the neutralized residue, adding 90 L of water to make a slurry, and adjusting the pH value to 0.10 (74 ° C.) by adding 75% sulfuric acid, The temperature was maintained while directly blowing saturated steam having a pressure of 0.5 MPa, and leaching was performed for 1 hour. The slurry after the leaching was subjected to solid-liquid separation by a filter press, the secondary leaching liquid according to the first half was collected, and after passing through the filter press for washing, the secondary leaching residue and the secondary washing water according to the first half were collected. The recovered secondary leaching residue is 85 kg · wet (water content 23.5% by mass), containing 2.9% by mass of arsenic, 3.0% by mass of Cu, and 4.6% by mass of Fe. Met. The secondary leaching residue is obtained when the material to be leached in the secondary leaching process described above becomes a neutralized residue produced in the original liquid preparation process, that is, when the process is in a steady state. is there.

[3 (2)] Secondary leaching process (second half of the second batch)
In the second half of the secondary leaching process according to the second batch, the secondary leaching solution 160L obtained in the first half is repeatedly used as the water to the secondary leaching process, and the primary leaching residue 190 kg · wet is added, and further 75% After adjusting the pH value to 0.26 (73 ° C.) by adding sulfuric acid, the temperature was maintained while saturating steam with a pressure of 0.5 MPa, and leaching was performed for 1 hour. The slurry after the secondary leaching is separated into solid and liquid by a filter press, and the secondary leaching liquid in the latter half is collected, washed with water through the filter press, and then the secondary leaching residue and the secondary washing water in the latter half. Was recovered. The arsenic concentration in the secondary leachate was 25.0 g / L.

[4 (2)] Original solution preparation process (second batch)
In the original liquid preparation process according to the second batch, the secondary leaching liquid obtained in the latter half of the secondary leaching process was used. The primary leaching residue was added to 250 L of the secondary leaching solution and stirred for 45 minutes to neutralize excess acid, and the pH value of the neutralized slurry was adjusted to 0.26 (35 ° C.). At this time, the liquid potential of the slurry was 432 mV (vs; Ag / AgCl). A small amount was sampled here. From the analysis result of the sample, 445 mg / L of Pb and 930 mg / L of Bi are dissolved in the slurry, and divalent Fe accounts for the total Fe concentration (total concentration of divalent Fe and trivalent Fe). The percentage was found to be 40%.
Subsequently, 12.3 kg · wet of copper removal electrolytic slime was added and allowed to react for 80 minutes to complete the reduction purification reaction. The slurry at this point had a pH value of 0.60 (34 ° C.) and a liquid potential of 187 mV (vs; Ag / AgCl).
The slurry after the original liquid preparation process related to the second batch is subjected to solid-liquid separation by a filter press to recover the crystallization original liquid related to the second batch, and further washed with water through the filter press. The neutralized residue and water-washing water related to the batch were collected.

  Table 11 shows the composition of the obtained crystallization liquid. The ratio of divalent Fe in the crystallization liquid to the total Fe concentration (total concentration of divalent Fe and trivalent Fe) was almost 100%.

[5] Crystallization step (first batch)
In the crystallization step, 311L of the crystallization original solution obtained in the original solution preparation step relating to the first batch is filled in a tank having a stirring means, and 19.0 kg of industrial ferrous sulfate is added and dissolved. And warmed to 95 ° C.
Next, when the reaction reached 95 ° C., the reaction was started, and oxygen gas was blown from the bottom of the tank at a rate of 30 L / min. The agitation by blowing was carried out at a strength at which gas-liquid mixing was sufficiently guaranteed, and the reaction was carried out under the conditions up to 9 hours. The pH value at the end of the crystallization step was 0.27 (95 ° C.), and the arsenic concentration in the solution after crystallization was 0.65 g / L.

The slurry after the crystallization step was subjected to solid-liquid separation with a filter press to obtain scorodite. The obtained scorodite was repulped with 600 L of water for 1 hour using a washing tank.
The washed scorodite was solid-liquid separated by a filter press, and the scorodite after the first batch was collected.

  The scorodite recovered by the above operation was 36.6 kg · wet (water content 22.5% by mass). Then, a part of the collected scorodite was subjected to a dissolution test and a composition analysis.

  Table 12 shows the average particle diameter, composition, and water content of the obtained scorodite, and Table 13 shows the reference value of the TCLP dissolution test and the evaluation result of scorodite according to Example 2.

[5] Crystallization step (second batch)
In the crystallization step, 20.2 kg of industrial ferrous sulfate and scorodite obtained in the previous first batch are added to the crystallization raw solution 267L obtained in the original solution preparation step related to the second batch. 9 kg · wet was added as a seed crystal.
Next, the mixture was heated to 95 ° C., and when reaching 95 ° C., the reaction was started, and oxygen gas was blown from the bottom of the tank at a rate of 30 L / min.
The agitation by blowing was carried out with a strength that sufficiently ensured gas-liquid mixing, and the reaction was carried out under the conditions up to 9 hours. The pH value at the end of the crystallization step was 0.21 (95 ° C.), and the arsenic concentration in the solution after crystallization was 0.55 g / L.

The slurry after the crystallization step was subjected to solid-liquid separation with a filter press to obtain scorodite. The obtained scorodite was repulped with 600 L of water for 1 hour using a washing tank.
The washed scorodite was solid-liquid separated by a filter press, and the washed scorodite according to the second batch was collected.

The scorodite recovered by the above operation was 45.1 kg · wet (water content 19.5 mass%). Then, a part of the collected scorodite was subjected to a dissolution test and a composition analysis.
Table 12 shows the average particle diameter, composition, and water content of the obtained scorodite, and Table 13 shows the standard value of the TCLP dissolution test and the evaluation result of the scorodite according to Example 2.

[Comparison of scorodite obtained in the first batch of crystallization and scorodite obtained in the second batch]
As described above, the scorodite obtained in both batches of the first batch and the second batch of crystallization was subjected to the TCLP dissolution test determined by the US Environmental Protection Agency (EPA). It was found that not only arsenic but also all the heavy metals specified satisfied the standard value.
Furthermore, it was found that the scorodite obtained in the second batch to which the seed crystals were added had an average particle size of 8.8 μm and was enlarged almost twice as much as the scorodite obtained in the first batch. .

[Smelting ash treatment for the second batch]
When the total amount of arsenic contained in the original smelting ash and decopperized electrolytic slime is 100%, the leachate in the secondary leaching process described above is the neutralized residue produced in the original liquid preparation process. As for the distribution of arsenic at the time when the process became steady, that is, when the process became steady, it was found that 69% of arsenic can be recovered as scorodite. This means that about 98% of the arsenic that can be leached from the smelting ash and the decopperized electrolytic slime can be converted to scorodite.
On the other hand, a total of 88% of Cu can be recovered as the primary leaching solution and the crystallization solution.
In addition, in this processing method using the smelting ash and the decoppered electrolytic slime, it is possible to process about 50 kg · wet of the decoppered electrolytic slime per ton of the smelted ash.

Claims (13)

A method for obtaining scorodite from non-ferrous smelting ash containing arsenic, Fe and Cu,
Slurry the non-ferrous smelting ash and add a pH adjuster. Add the oxidant while controlling the pH value of the non-ferrous smelting ash slurry within the range of 1.5 to 3.0. A primary leaching end slurry, and filtering the primary leaching end slurry to obtain a primary leaching solution and a primary leaching residue;
Slurrying the primary leaching residue, adding sulfuric acid, acid leaching to form a secondary leaching complete slurry, and filtering the secondary leaching complete slurry to obtain a secondary leaching solution and a secondary leaching residue; ,
The primary leaching residue is added to the secondary leaching solution to neutralize the acid content in the secondary leaching solution to obtain a neutralized slurry, and then dissolved in the neutralized slurry in the neutralized slurry 5 Bi, Pb, Sb, which are impurity elements dissolved in the neutralized slurry, are added by adding a liquid modifier that reduces trivalent Fe to divalent Fe while suppressing reduction of trivalent arsenic to trivalent arsenic. At least one type of Sn is reduced to obtain an original liquid preparation completion slurry, and after the reduction of the trivalent Fe to divalent Fe, the original liquid preparation completion slurry is filtered to obtain a crystallization original liquid and a neutralized residue. An original liquid preparation step to obtain;
And a crystallization step of producing scorodite from the crystallization raw liquid. A method for producing scorodite from nonferrous smelting ash.   The alkali is added to the primary leaching end slurry in the primary leaching step, neutralized so that the pH value is 3.5 or less at the maximum, and then the primary leaching step is ended. A method for producing scorodite from non-ferrous smelting ash according to 1.   An acid is added to the non-ferrous smelting ash slurry, and a preliminary leaching step is performed in which the acid-added slurry is leached with a pH value of 0.1 to 1.0, and water is added to the acid-added slurry after completion of the preliminary leaching step. 3. The non-additive slurry according to claim 1, wherein the acid addition slurry is subjected to the primary leaching step after the acid concentration of the acid addition slurry is reduced by adding a neutralizing agent. A method for producing scorodite from iron smelting ash. The method for producing scorodite from non-ferrous smelting ash according to claim 3, wherein the preliminary leaching step and the primary leaching step are sequentially performed in one reaction tank.   The neutralized residue obtained in the original liquid preparation step is repeated in the secondary leaching step, and arsenic contained in the neutralized residue is leached. A method for producing scorodite from non-ferrous smelting ash described in 1.   6. The secondary leaching solution obtained in the secondary leaching step is repeated to the secondary leaching step to concentrate arsenic contained in the secondary leaching solution. Of producing scorodite from non-ferrous smelting ash.   The method for producing scorodite from non-ferrous smelting ash according to any one of claims 1 to 6, wherein the liquid quality adjusting agent used in the original liquid preparation step is metallic Fe and / or copper removal electrolytic slime. Claims wherein the non-ferrous smelting Kemurihai slurry was added a pre-Fe source, the Fe and arsenic mole ratio of dissolved in the secondary leaching solution (Fe / As molar ratio), characterized in that so as to be 1 or more Item 8. A method for producing scorodite from non-ferrous smelting ash according to any one of Items 1 to 7.   The method for producing scorodite from non-ferrous smelting ash according to any one of claims 1 to 8, wherein the oxidizing agent added in the primary leaching step is a hydrogen peroxide solution.   The liquid quality adjusting agent to be added in the original liquid preparation step is metal Fe and / or decopperized electrolytic slime and strontium carbonate, from the non-ferrous smelting ash according to any one of claims 1 to 9 Scorodite manufacturing method.   The method for producing scorodite from non-ferrous smelting ash according to any one of claims 1 to 10, wherein the pH adjuster added in the primary leaching step is sulfuric acid or an alkali containing Ca.   In the crystallization step, scorodite production reaction is performed by blowing air or oxygen or a mixed gas of air and oxygen into the crystallization liquid at 80 ° C. or higher under atmospheric pressure, and the slurry after completion of the scorodite production reaction The method for producing scorodite from non-ferrous smelting ash according to any one of claims 1 to 11, wherein the scorodite is obtained by filtering the sucrose.   The nonferrous smelting method according to any one of claims 1 to 12, wherein the scorodite obtained in the crystallization step is used as a seed crystal in a scorodite production reaction in the crystallization step of the next batch. A method for producing scorodite from smoke ash.

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