JPH0649556A - Method for dissolving and recovering zinc from metallic zinc-containing material - Google Patents

Abstract

PURPOSE:To dissolve zinc at a high rate and to efficiently recover zinc by bringing a metallic zinc-contg. material into contact with aq. ammonia, etc., and blowing oxygen into the soln. in the presence of an ammine copper complex to selectively dissolve zinc which is recovered. CONSTITUTION:A zinc-contg. material is brought into contact with an aq. soln. contg. ammonia and ammonium carbonate. In this case, an oxygen-contg. gas is blown into the soln. in the presence of an ammine copper (II) complex to selectively dissolve zinc into the soln. as an ammine zinc complex. Metallic zinc is added to the soln., and the precipitate is separated to provide a refined aq. soln. The ammine zinc complex in the soln. is then decomposed to precipitate basic zinc carbonate, and high-purity zinc is recovered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dissolving and recovering zinc from a material containing metallic zinc. For more details,
The present invention relates to a method of contacting a metal zinc-containing material with an aqueous solution containing ammonia and ammonium carbonate, selectively dissolving zinc as an ammine complex, and then thermally decomposing this complex to recover zinc as basic zinc carbonate. In the above, there is provided a method that enables rapid dissolution of zinc.

[0002]

2. Description of the Related Art Metal zinc-containing substances (hereinafter referred to as zinc-containing substances) containing metal zinc at a considerably high concentration are discharged from steel mill facilities, such as zinc plating-related facilities and dust collectors of scrap melting furnaces. Therefore, it is desirable to separate and recover the zinc and use it effectively as a resource. At that time, it is desired to recover high-purity zinc containing as little as possible the content of coexisting impurity metals such as Fe and Pb.

As a method for treating the zinc-containing material as described above, Japanese Patent Publication No. 2-35693 discloses that the zinc-containing material is contacted with an aqueous solution containing ammonia and ammonium carbonate,
A method has been proposed in which zinc is selectively dissolved as an ammine complex and recovered. The dissolution reaction of zinc at this time is (1)
It is as the formula says.

Zn + (NH ₄ ) ₂ CO ₃ + 2 NH ₃ → Zn (NH ₃ ) ₄ CO ₃ + H ₂ ↑ (1) In the aqueous solution in which zinc is dissolved in this way, metallic zinc (even if the raw material contains zinc) Is added, and an ion substitution reaction is performed between metallic zinc and the impurity metal dissolved in the aqueous solution to precipitate the impurity metal and purify the aqueous solution. When ammonia and carbon dioxide are removed by heating and / or reduced pressure from the purified aqueous solution obtained after removing the precipitate, the ammine zinc complex is decomposed and the basic zinc carbonate is precipitated, which is recovered. The decomposition reaction at this time is
It is expressed by equation (2).

5 [Zn (NH ₃ ) ₄ CO ₃ ] → [ZnCO ₃ ] ₂ [Zn (OH) ₂ ] ₃ ↓ + 3 CO ₂ ↑ + 20 NH ₃ ↑ ・ ・ ・ (2) Ammonia generated by decomposition reaction When carbon dioxide gas is absorbed into an aqueous solution used for dissolving zinc, ammonia and ammonium carbonate used for dissolution are regenerated. Therefore,
It is characterized in that the aqueous solution for dissolution can be circulated and used only by replenishing the carbon dioxide gas required for the production of basic zinc carbonate, and the chemical solution cost and the waste solution treatment cost can be significantly reduced.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above,
The method of recovering zinc via an ammine zinc complex is low in cost and can recover high-purity zinc, but has a problem that the dissolution reaction of zinc according to the above formula (1) is slow. Therefore, the treatment time in the dissolution step is very long, and the zinc-containing material having a particle size of 1 mm or more is difficult to treat, so it is necessary to remove it beforehand by sieving.

It is an object of the present invention to provide a zinc dissolution method with an increased dissolution rate when zinc is dissolved as an amminezinc complex so that zinc-containing materials having a larger particle size can be treated. Another object of the present invention is to provide a method for recovering zinc from a zinc-containing material, which is more efficient and economical than before by utilizing this dissolution method.

[0008]

The method for dissolving zinc from a zinc-containing material according to the present invention comprises contacting the zinc-containing material with an aqueous solution containing ammonia and ammonium carbonate in a reaction vessel so that zinc is contained in the aqueous solution. When dissolved as a complex, it is characterized in that the dissolution is carried out in the presence of an ammine copper (II) complex while blowing an oxygen-containing gas into the aqueous solution.

The method for recovering zinc from a zinc-containing material according to the present invention comprises a step of bringing the zinc-containing material into contact with an aqueous solution containing ammonia and ammonium carbonate in a reaction vessel to dissolve zinc as an ammine zinc complex in the aqueous solution. 1. Step 2 of purifying the obtained aqueous solution by adding metallic zinc to obtain a purified aqueous solution by separating the precipitate 2. Decomposing the ammine zinc complex in the purified aqueous solution to remove the precipitated basic zinc carbonate. The method for recovering zinc from a zinc-containing material, which comprises the step 3 of recovering, is characterized in that the dissolving step is carried out in the presence of an ammine copper (II) complex while blowing an oxygen-containing gas into the aqueous solution.

In a preferred embodiment of this zinc recovery method, the copper-containing precipitate separated in step 2 and the ammonia and carbon dioxide gas generated in step 3 are circulated in the aqueous solution of step 1 to produce an ammine. Ammonia is recycled with regeneration of the copper (II) complex and ammonium carbonate.

Further, in any of the above-mentioned zinc dissolution method and recovery method, when the dissolution of zinc is carried out by continuously supplying the zinc-containing material into the reaction vessel, the supply rate is set to the inside of the reaction vessel. It is preferable to adjust the ratio of copper (II) ions to the total copper to be 40 to 60% from the viewpoint of the treatment efficiency of the reaction tank.

[0012]

The function of the present invention will be described below in detail for each step along with its function. A flow sheet of the zinc recovery method according to the present invention is shown in FIG.

Examples of the zinc-containing material to which the method for dissolving and recovering zinc according to the present invention can be applied: Zinc dust produced as a by-product of the steel mill obtained from the zinc plating auxiliary equipment in the steel mill and the dust collector of the scrap melting furnace. However, the present invention is not limited to this. The method of the present invention can be applied to any zinc-containing material containing metallic zinc in a proportion of about 10% by weight or more. If necessary, the zinc-containing material to be treated is preferably subdivided into about 10 mm or less before the treatment.

Zinc Dissolving Step (Step 1) In the dissolving step, the zinc-containing substance is brought into contact with an aqueous solution containing an ammine copper (II) complex, ammonia and ammonium carbonate in a reaction tank, and an oxygen-containing gas is added to the aqueous solution. By blowing, zinc is selectively dissolved as an ammine zinc complex from the zinc-containing material. That is, since this step is leaching of zinc from the zinc-containing material, the aqueous solution containing the ammine copper (II) complex, ammonia and ammonium carbonate used in this step may be referred to as a leaching solution hereinafter.

(A) Effect of oxygen blowing The conventional dissolution method used an aqueous solution containing ammonia and ammonium carbonate as a leachate, and merely contacted the zinc-containing material with this solution without blowing an oxygen-containing gas. In this case, zinc dissolves as in the above formula (1),
Hydrogen is generated. As mentioned above, this dissolution reaction is slow and requires a long time for dissolution. Therefore, the present inventor tried to blow an oxygen-containing gas into the leachate.
In this case, zinc is directly oxidized by oxygen and dissolved as shown in the following formula (3).

Zn + 2 (NH ₄ ) ₂ CO ₃ + 2 NH ₃ + 1/2 O ₂ → Zn (NH ₃ ) ₄ CO ₃ + H ₂ O (3) However, even if an oxygen-containing gas is blown in, Experiments have revealed that the diffusion of oxygen into zinc metal is rate-determining, and the dissolution rate of zinc is only as high as when oxygen-containing gas is not blown.

However, in the presence of oxygen, a part of the impurity metal such as iron is passivated, so that there is an effect that the dissolution of the impurity metal can be suppressed. In particular, when the zinc-containing substance contains a large amount of iron, the dissolution of iron is significantly suppressed by the blowing of the oxygen-containing gas, and a zinc-containing aqueous solution containing few impurities can be obtained.

(B) Combined effect of ammine copper (II) complex and oxygen blowing In order to dissolve zinc more quickly, in addition to blowing oxygen-containing gas into the leachate, ammine copper (II) complex was added to the leachate.
We tried to make the complex coexist. As a result, the dissolution rate of zinc could be significantly increased. The dissolution reaction of zinc in this case is shown below.

Zn + Cu (II) (NH ₃ ) ₄ CO ₃ → Zn (NH ₃ ) ₄ CO ₃ + Cu (4) Cu + Cu (II) (NH ₃ ) ₄ CO ₃ → [Cu (I _{) (NH 3) 2] 2} CO 3 ‥‥ (5) [Cu (I) (NH 3) 2] 2 CO 3 + (NH 4) 2 CO 3 + 2
NH ₃ + 1/2 O ₂ → 2 Cu (II) (NH ₃ ) ₄ CO ₃ + H
₂ O (6) That is, when an ammine copper (II) complex coexists in the leachate, zinc is dissolved by a substitution reaction with Cu (II) ions as shown in the formula (4). In this reaction, Cu (II) ions are reduced to metallic Cu and consumed, but in the presence of oxygen, the formula (5) and
It is regenerated into an ammine copper (II) complex through the reaction represented by the formula (6). Therefore, the total dissolution reaction of zinc, which is obtained by combining the above formulas (4) to (6), is the same as the reaction represented by formula (3) as in the case where the ammine copper (II) complex is not present.

As described above, the Cu component does not change as a whole, but the reaction rate is significantly accelerated as compared with the case where the ammine copper (II) complex does not coexist. For example, when the ammine copper (II) complex is not present, as shown in Examples described later,
The dissolution time required from 10 hours is reduced to only 30 minutes. Further, it becomes possible to easily dissolve the zinc-containing material even if the particle size is larger than 1 mm.

The melting step is carried out while blowing an oxygen-containing gas such as air or pure oxygen into the leachate. The reaction tank used in the dissolution step may be a closed system or an open system. In the case of a closed system, oxygen can be blown in by circulating an oxygen-containing gas between the reaction chamber upper space and the aqueous solution using a pump. In the case of an open system, a part of ammonia in the aqueous solution is volatilized by blowing the oxygen-containing gas, and therefore it is preferable to recover the ammonia by an existing method.

An aqueous solution containing ammonia, ammonium carbonate and an ammine copper (II) complex used as a leachate is prepared by blowing ammonia gas and carbon dioxide gas into water, and before or after the blowing, metallic copper or a suitable copper compound. (Eg, cupric oxide, cupric hydroxide) can be added and dissolved. When dissolving metallic copper, it is necessary to blow oxygen at the same time. Ammonium carbonate is produced by the reaction of ammonia, carbon dioxide gas and water, and ammine copper (II) complex is produced by the reaction of copper, ammonia, ammonium carbonate and oxygen. Ammonia concentration in the aqueous solution is 0.2-6M, ammonium carbonate concentration is 0.1-3M,
The ammine copper (II) complex concentration is preferably about 0.1 to 2M.

The pH of the aqueous solution is usually adjusted to be in the range of 8-12. If the temperature of the aqueous solution is too low, the dissolution rate of zinc will be slow, and if it is too high, the volatilization of ammonia will be large and the stability of the amminezinc complex will be low.

The dissolution step is preferably a batch operation in which the leachate and the zinc-containing material are added to the reaction vessel all at once and brought into contact with each other until the zinc in the zinc-containing material is almost completely dissolved. As described above, in the present invention, this time is much shorter than in the conventional case, and depending on the conditions, the dissolution of zinc can be completed in about 30 minutes.

In the continuous operation for continuously supplying the leachate and the zinc-containing material to the reaction tank or the semi-continuous operation for continuously supplying the zinc-containing material into the leachate previously charged in the reaction tank, As described in, when the supply rate of the zinc-containing material is adjusted to a rate such that the ratio of copper ions to the total copper in the reaction tank is 40 to 60%, the treatment efficiency of the reaction tank increases,
preferable.

(C) Treatment Efficiency of Dissolving Reaction Tank in Continuous Type or Semi-Continuous Type When the melting step is performed by a continuous type or a semi-continuous type operation, the zinc-containing material is continuously supplied into the reaction vessel. . In this case, the treatment efficiency of the reaction tank (the amount of zinc dissolved per unit effective volume of the reaction tank in a unit time) is generally considered to be that the feed rate of the zinc-containing raw material is high if other conditions are constant. The higher the zinc dissolution amount, the higher the treatment efficiency should be. However, it has been found that the treatment efficiency initially increases with an increase in the supply rate of the zinc-containing material, but rather suddenly decreases above a certain supply rate.

Therefore, it is desirable to supply the zinc-containing material at a rate that maximizes the treatment efficiency. However, the concentration of the ammine copper (II) complex, ammonium carbonate, ammonia, oxygen in the leaching solution, the temperature, etc. are included. It was difficult to find the condition that maximizes the processing efficiency because various factors have a complicated influence.

The present inventors have studied this point in a semi-continuous dissolution experiment, and as a result, the ratio of copper (II) ions to total copper in the reaction tank is defined as [Cu ²⁺ / total Cu ratio]. It was found that the dissolution rate of copper has a high correlation with the treatment efficiency. That is, as shown in FIG. 2, it was found that the treatment efficiency was maximum when the copper dissolution rate was around 50%, and high treatment efficiency was obtained within the range of 40 to 60%.

As described above, in the method of the present invention, copper is introduced into the reaction vessel as an ammine copper (II) complex, that is, copper (II) ion, and is temporarily converted into a metal by the substitution reaction with zinc according to the formula (4). Precipitates as copper. From the deposited copper, the ammine copper (II) complex is regenerated by the reactions shown in formulas (5) and (6). That is, the copper in the reaction tank during the dissolution treatment exists in two states: precipitated metal copper and dissolved copper (II) ions.

The dissolution rate of copper depends on the total copper in the reaction tank during the treatment.
[That is, it can be determined as the ratio of the concentration of copper (II) ions present in the dissolved state to the concentration of copper (II) ions + metallic copper]. The total copper concentration corresponds to the concentration of the ammine copper (II) complex in the leachate supplied to the reaction tank, so if you extract the aqueous solution from the reaction tank being treated and analyze its copper (II) ion concentration,
The dissolution rate of copper can be measured.

When the supply rate of the zinc-containing material is slow, (4)
The amount of metallic copper deposited by the formula is small, and the deposited metallic copper is regenerated by the formulas (5) to (6), so the copper dissolution rate becomes high. However, in this case, the amount of metal zinc that is a melting raw material is smaller than the processing capacity of the reaction tank, so that the processing efficiency decreases. It is for this reason that the treatment efficiency decreases when the copper dissolution rate exceeds 60%.

On the other hand, even if the supply rate of the zinc-containing material is too fast, the treatment efficiency is lowered because if the supply of metallic zinc is too much, the regeneration of the copper (II) ion according to the equations (5) to (6) is performed. The reason for this is that the copper (II) ions introduced into the reaction system almost remain in the state of metallic copper reduced by metallic zinc. When the dissolution rate of copper is less than 40%, the treatment efficiency decreases because the supply of zinc-containing material is too fast and the supply of copper (II) ions required for rapid dissolution of metallic zinc cannot keep up. It means that.

When the copper dissolution rate is around 50%, the copper consumption reaction of the formula (4) and the copper regeneration reaction of the formulas (5) to (6) proceed in the most balanced manner, and the treatment efficiency of the reaction tank is improved. It will be the maximum. In this way, in the case of continuously supplying the zinc-containing material to the reaction tank in a continuous system or a semi-continuous system, the dissolution rate of copper during the process serves as an index of the reaction efficiency of the reaction tank, and the efficiency of the reaction tank is increased. In particular, it is preferable to supply the zinc-containing material at a rate such that the copper dissolution rate is 40 to 60%.

The liquid discharged from the dissolution step is separated into an aqueous solution and an undissolved residue by a suitable solid-liquid separation means such as filtration, sedimentation, decantation, and overflow. The obtained aqueous solution contains ammine copper (II) in addition to the ammine zinc complex produced by dissolution of zinc.
It contains small amounts of other amine ammine complexes derived from the complex and impurities, as well as unconsumed ammonia and ammonium carbonate. If the concentration of ammonia and ammonium carbonate remaining in this aqueous solution is high enough to dissolve zinc according to formula (3), dissolve the aqueous solution once or twice or more before subjecting it to the next step. You may use for processing.

Purification Step of Zinc-Containing Aqueous Solution (Step 2) Metal zinc is added to an aqueous solution containing zinc, copper (II) and a small amount of an ammine complex of an impurity metal obtained in the dissolving step to add copper (II) and impurities. The metal ion is precipitated as a metal by an ion substitution reaction with metal zinc to purify the aqueous solution. Similar to the dissolution step, zinc dissolves as an ammine zinc complex as shown in the above formula (4), and copper and other impurity metals precipitate and precipitate.

In the dissolving step, an oxygen-containing gas is blown into the solution so that the produced metallic copper is redissolved by oxidation and copper (II) is rapidly regenerated, but in the refining step, metallic copper is deposited as it is. Remove. Therefore, if necessary, the system may be kept under an inert gas atmosphere so as to prevent re-dissolution of the deposited copper. However, unless the oxygen-containing gas is blown in, redissolution by oxidation of copper is generally slow, and therefore it is not usually necessary to use an inert gas atmosphere.

The metallic zinc added in the refining step does not have to be a pure product. For example, if the zinc content is high, such as zinc dust generated in a galvanizing accessory facility, the zinc-containing material that is the raw material of the method of the present invention can be used as metallic zinc in the refining step. In this case, the raw material zinc-containing material is used in both the dissolution step 1 and the purification step 2, and is dissolved in the aqueous solution as an ammine zinc complex in both steps. The amount of zinc metal added is preferably an excess amount over the amount required to replace the copper (II) ions and the impurity metal ions dissolved in the aqueous solution. Even if the undissolved metallic zinc remains, it can be recovered by dissolving it in the dissolving aqueous solution by circulating the precipitate in the dissolving step as described later.

The purification step is preferably carried out at a temperature of room temperature to 80 ° C. under stirring. A treatment time of about 5 to 30 minutes is usually sufficient. Thereafter, the deposited metal copper-based precipitate is separated and removed by a means such as filtration to obtain a purified aqueous solution of the ammine zinc complex.

The separated metal copper-based precipitate is
It is preferable to circulate it in the aqueous solution used as the leachate for dissolving zinc in step 1 (dissolution step). The metallic copper added to the aqueous solution undergoes the reactions represented by the equations (5) and (6) in the dissolution step to regenerate the ammine copper (II) complex. At the same time, undissolved metallic zinc contained in the precipitate also dissolves in the aqueous solution as an ammine zinc complex. In this way, ammine copper (I
The I) complex can be reused for the dissolution of zinc, so replenishment is hardly necessary.

Step of Decomposing Ammine Zinc Complex (Step 3) When the purified aqueous solution of ammine zinc complex is heated and / or treated under reduced pressure, the complex is decomposed by the reaction of the above formula (2), and a water-insoluble basic carbonic acid is obtained. Zinc precipitates and is recovered by means such as filtration. Decomposition, for example,
It can be carried out by heating the purified aqueous solution to a temperature of 90 ° C. or higher with an appropriate crystallizer. A two-stage crystallization method may be used as described in JP-B-2-35693. The mother liquor for crystallization may be returned to the crystallization step to completely recover the Zn content remaining in the mother liquor. The recovered basic zinc carbonate is usually washed with water and dried before being used as a product.

Ammonia and carbon dioxide gas generated by the decomposition of the amminezinc complex are preferably recovered and circulated in the aqueous solution used for dissolution, either as they are or after being absorbed by water. As a result, the ammonia and ammonium carbonate used for dissolution are also regenerated. That is, of the agents used to dissolve zinc, the one consumed by the method of the present invention is
In principle, it is only the amount of carbon dioxide gas required for the formation of basic zinc carbonate, and the rest of the carbon dioxide gas and the total amount of ammonia and the ammine copper (II) complex can be recycled. If there is a gas generated in the dissolving step 1 or the refining step 2, it is preferable to similarly circulate these gases in the aqueous solution for dissolving. Therefore, for ammonia and ammine copper (II) complexes,
The operation can be continued by replenishing the slight amount lost due to taking out, etc., and in addition to the ammine copper (II) complex,
Most of ammonia and more than half of carbon dioxide can be recycled.

The zinc dissolution and recovery method of the present invention can be carried out in any of batch system, continuous system and semi-continuous system, and can be carried out industrially though different systems can be adopted for each process. In some cases, it may be advantageous to carry out each step in a continuous or semi-continuous operation.

[0043]

EXAMPLES The present invention will be further described below with reference to examples. In the examples,% is% by weight unless otherwise specified.

Example 1 Ammine copper (II) on the dissolution rate of zinc using a zinc plate
The effect of complex concentration was investigated. 1.0 M ammonia, 0.
The zinc plate was immersed in 2 L (liter) of an aqueous solution containing ammonium carbonate of 5 M concentration and an ammine copper (II) complex [Cu (II) (NH ₃ ) ₄ CO ₃ ] of various concentrations at a temperature of 40 ° C. Pure oxygen gas 10
The aqueous solution was sampled at regular intervals while being blown at a flow rate of L / min, and the dissolution rate of zinc was determined from the change in Zn concentration in the aqueous solution. The results are shown in Table 1 below. From this result, it is found that the dissolution rate of zinc significantly increases as the concentration of the ammine copper (II) complex in the aqueous solution increases.

[0045]

[Table 1]

Example 2 Zinc dust (T-Zn 9 generated from a small diameter galvanizing plant)
9.0%, metal Zn 98.5%, Fe 0.2%, Pb 0.7%, Cd 0.1%) was used as a melting raw material, and zinc was recovered therefrom by the method of the present invention.

Dissolution step Ammonia concentration 2.0 M, ammonium carbonate concentration 1.0 M,
Ammine copper (II) complex concentration 0.31M temperature 60 ℃ aqueous solution 1L
6 L of pure oxygen gas in the aqueous solution at 60 ° C.
While blowing at a flow rate of / min, 70 g of the above zinc dust was gradually supplied to dissolve zinc, and the zinc content was completely dissolved in 30 minutes. The residue was filtered off and the Zn concentration was 69 g / L.
An aqueous solution of For comparison, when an aqueous solution containing no ammine copper (II) complex was used and treated in the same manner as above, it took about 10 hours to dissolve the zinc component.

Purification step In the aqueous solution having a Zn concentration of 69 g / L thus obtained by the dissolution method of the present invention, 30 g of the same zinc dust used as the dissolution raw material
Was charged and the aqueous solution was stirred for about 15 minutes at a temperature of 60 ° C. without blowing oxygen, and the copper content in the solution could be almost completely precipitated as metallic copper. The precipitate is filtered,
A purified ammine zinc complex aqueous solution with a Zn concentration of 89 g / L was obtained. The impurity concentration in this aqueous solution was Fe 8 ppm, Pb 15 ppm,
It was Cu 3 ppm.

Step for recovering zinc carbonate Using this purified zinc solution, a 90-
The ammonium and carbon dioxide gas was evaporated at 100 ° C. to decompose the ammine zinc complex into basic zinc carbonate and crystallize. The crystallized crystals were separated by filtration, washed with water and dried to give 99.98% pure basic zinc carbonate (Fe 63 pp
m, Pb 110 ppm, Cu 24 ppm) were recovered. The recovery rate of Zn was about 90% based on the total amount of Zn added in the dissolution step and the purification step. Most of the uncollected Zn is
Undissolved Zn is contained in the precipitate of the purification step as undissolved metallic zinc, and by recycling this precipitate in the dissolution step, undissolved Zn can be recovered. With this, the recovery rate of Zn is about 10
It becomes 0%.

Circulation of By-Products The gas discharged in the dissolution step and the gas generated during crystallization are absorbed in water to recover ammonia and carbon dioxide gas, and the obtained aqueous solution containing ammonia and ammonium carbonate is mixed with carbon dioxide. By blowing gas and a small amount of ammonia gas and dissolving the precipitate separated in the purification step in this aqueous solution, it was possible to regenerate an aqueous solution for dissolution having substantially the same concentration as that used in the above dissolution step.

Example 3 Reaction of an effective volume of 100 L using the same zinc dust as that used in Example 2 as a melting raw material and equipped with the gas blowing / circulation system and the zinc dust continuous feeding device shown in FIG. The dissolution experiment was performed several times in a semi-continuous manner using a tank.

An aqueous solution having an ammonia concentration of 4.0 M, an ammonium carbonate concentration of 2.0 M, and an ammine copper (II) complex concentration of 0.2 M was placed in a reaction tank, and oxygen gas was added to the aqueous solution at an aqueous solution temperature of 60 ° C.
12 kg of the above zinc dust while blowing at a flow rate of 150 L / min
Was added at a constant constant feed rate each time, and zinc was dissolved in the liquid. The treatment efficiency (G / L · h) was determined from the treatment time until the dissolution of zinc dust was completed, and the copper (II) ion concentration in the aqueous solution during the treatment was analyzed by atomic absorption spectrometry. This analysis is performed at intervals of 2 to 5 minutes, and the molar concentration when the copper (II) ion concentration reaches a constant value
I) The ion concentration. Usually, the copper (II) ion concentration became constant within 10 minutes. The copper dissolution rate was calculated from the ratio of this copper (II) ion concentration to the copper (II) ion concentration (0.2 M) in the charged aqueous solution. The results of copper dissolution rate and treatment efficiency are shown in Table 2 below.

[0053]

[Table 2]

FIG. 2 graphically shows this result. From this figure and Table 2, the dissolution rate of copper decreases as the feed rate increases, but the treatment efficiency reaches the maximum when the dissolution rate of copper is around 50%, and the dissolution rate of copper is within the range of 40-60%. It can be seen that extremely high processing efficiency can be obtained. That is, the dissolution rate of copper, and hence the concentration of copper (II) ions in the aqueous solution, has a large effect on the improvement of treatment efficiency. From this, under the conditions of this example, the supply rate of the zinc-containing material is about 300 to 355 g / so that the dissolution rate of copper falls within the range of 40 to 60%.
Continuous feeding within the min range optimizes the treatment efficiency of the reaction vessel.

Example 4 Ammonia concentration 4.0 M, ammonium carbonate concentration 2.0 M,
An aqueous solution having an ammine copper (II) complex concentration of 0.3 M was placed in the reaction vessel shown in FIG. 3, and oxygen gas was added to the aqueous solution at a temperature of 60 ° C.
12 kg of the same zinc dust used in Example 2 was continuously fed while blowing at a flow rate of 170 L / min. The dissolution rate of copper was measured every 2 minutes from the start of the supply of zinc dust, and the supply rate was adjusted so that the dissolution rate of copper was around 50%. As a result, it was found that when zinc dust was supplied at a rate of 460 g / min, the copper dissolution rate became constant at 49%.
Under this condition, zinc dust could be completely dissolved in 28 minutes, and the treatment efficiency was 430 g / L · h.

[0056]

According to the method of the present invention, zinc in a zinc-containing material can be rapidly dissolved as an ammine zinc complex, and a zinc-containing material having a larger particle size than before can be treated.
Recovery of zinc becomes efficient. In principle, the method for recovering zinc of the present invention can recover the total amount of ammine copper (II) complex and ammonia and half or more of carbon dioxide gas among the chemicals to be used, and can recycle them, so that the material cost can be reduced. It is very inexpensive and does not use strong acids or bases, so wastewater treatment is easy and it is economical. Therefore,
The present invention is a technique that contributes to promotion of recycling of zinc contained in a zinc-containing material such as zinc dust.

Further, the treatment efficiency of the reaction vessel in the dissolution of zinc by the above method largely varies depending on the dissolution rate of copper during the processing (this decreases as the supply rate of the zinc-containing material increases), and the dissolution of copper The treatment efficiency is maximized by adjusting the feed rate of the zinc-containing material so that the rate is within the range of 40 to 60%, particularly preferably around 50%. Therefore, the optimum zinc supply rate can be easily determined using the dissolution rate of copper as a guide.

[Brief description of drawings]

FIG. 1 is a flow sheet of a zinc recovery method according to the present invention.

FIG. 2 is a graph showing a relationship between a dissolution rate of copper and a treatment efficiency of a reaction tank in dissolving zinc by continuously supplying a zinc-containing material.

FIG. 3 is a schematic diagram showing a configuration of a reaction tank used in Examples.

Claims (5)

[Claims] 1. A method of dissolving zinc as an ammine zinc complex in an aqueous solution by bringing a metal zinc-containing material into contact with an aqueous solution containing ammonia and ammonium carbonate in a reaction vessel, and dissolving zinc in the presence of an ammine copper (II) complex. A method characterized by carrying out while blowing an oxygen-containing gas into an aqueous solution below. 2. The contact is carried out by continuously supplying a metal-zinc-containing material into the reaction tank, and the supply rate is set such that the ratio of copper (II) ions to the total copper in the reaction tank is 40 to 60%. The method of claim 1, wherein the adjustment is 3. A step 1 of contacting a metallic zinc-containing material with an aqueous solution containing ammonia and ammonium carbonate in a reaction vessel to dissolve zinc as an ammine zinc complex in the aqueous solution, and adding the resulting aqueous solution to metallic zinc. Purifying according to step 2 and separating the precipitate to obtain a purified aqueous solution,
In the method for recovering zinc from a metal-zinc-containing material, which comprises the step 3 of decomposing the ammine zinc complex in the purified aqueous solution and recovering the precipitated basic zinc carbonate, the dissolving step includes coexisting with an ammine copper (II) complex. A method for recovering zinc from a metal-zinc-containing material, which is performed while blowing an oxygen-containing gas into an aqueous solution below. 4. The copper-based precipitate separated in step 2, the ammonia and carbon dioxide gas generated in step 3,
The method according to claim 3, wherein the ammonia is circulated while the ammine copper (II) complex and the ammonium carbonate are regenerated by circulating the aqueous solution of step 1. 5. The step 1 is carried out by continuously supplying a metallic zinc-containing material into the reaction tank, and the supply rate is set such that the ratio of copper (II) ions to the total copper in the reaction tank is 40 to 60%. The method according to claim 3 or 4, wherein the method is adjusted to