JP6174395B2 - Method for recovering copper and method for producing copper oxide - Google Patents

Description

  The present invention relates to a method for recovering copper and a method for producing copper oxide.

  In manufacturing a printed wiring board or the like, etching for dissolving metallic copper is performed for circuit formation. For this reason, a large amount of waste liquid containing copper ions is generated. The waste liquid containing copper ions cannot be discharged as it is because it may adversely affect the natural environment. Therefore, a method of physically solidifying the waste liquid, a method of metallizing copper ions using electricity, and the like have been put into practical use. As a method for physically solidifying the waste liquid, there are a precipitation method and a sintering method (for example, see Patent Documents 1 to 5). Moreover, as a method of metallizing copper ions using electricity, there is an electrodeposition method (see, for example, Patent Document 6).

Japanese Patent Laid-Open No. 11-60239 JP 2003-213346 A JP 2009-167462 A Japanese Patent Laid-Open No. 7-33435 JP-A-7-3475 JP 2002-60986 A

  The precipitation method requires a large-scale processing facility, and the process is complicated and includes many processes such as pH adjustment, addition of a precipitation aid, precipitation process, filtration process, and recovery process. Moreover, a long time is required for processing in each process. Furthermore, it is necessary to use a large amount of water. As described above, the sintering method requires a large-scale processing facility, and requires a temperature of 700 ° C. or higher during sintering. Therefore, a large amount of fossil fuel is required to obtain the combustion energy. As described above, the electrodeposition method requires large-scale equipment, and consumes a large amount of electricity although the processing time is short.

  In view of the above circumstances, an object of the present invention is to provide a method for recovering copper by a simple method with reduced energy consumption and a method for producing copper oxide.

  Means for solving the above problems are as follows.

<1> a step of preparing a mixture containing at least a copper ion, a low-grade coal, and a nitrogen atom-containing compound capable of forming a complex with copper, a step of taking out the low-grade coal carrying copper from the mixture, and the mixture And a step of heat-treating the low-grade coal taken out from the process.

<2> The copper recovery method according to <1>, wherein the temperature of the heat treatment is 600 ° C. or less.

<3> The copper recovery method according to <1> or <2>, wherein the mixture further contains water.

<4> The method for recovering copper according to any one of <1> to <3>, wherein the pH of the mixture at 25 ° C. is in the range of 8 to 11.

<5> preparing a mixture including at least a copper ion, a low-grade coal, and a nitrogen atom-containing compound capable of forming a complex with copper, a step of removing the low-grade coal carrying copper from the mixture, and the mixture And a step of heat-treating the low-grade coal taken out from the process.

  ADVANTAGE OF THE INVENTION According to this invention, energy consumption is suppressed and the method of collect | recovering copper by a simple method and the manufacturing method of copper oxide are provided.

  In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, in the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. Means.

<Copper recovery method>
The method for recovering copper according to the present invention includes a step of preparing a mixture including at least a copper ion, a low-grade coal, and a nitrogen atom-containing compound capable of forming a complex with copper, and the low-grade coal supporting copper from the mixture. And a step of heat-treating the low-grade coal extracted from the mixture.

  The method for preparing the mixture is not particularly limited. For example, by mixing a low-grade coal and a nitrogen atom-containing compound capable of forming a complex with copper (hereinafter, also simply referred to as a nitrogen atom-containing compound) into a waste liquid containing copper ions generated in a manufacturing process such as a printed wiring board. Can be prepared. The mixing method is not particularly limited. For example, a method in which a nitrogen atom-containing compound is mixed as it is or in a solution state with a solution such as a waste liquid containing copper ions, and then a low-grade coal is mixed. The mixture is preferably basic. For example, the pH at 25 ° C. is preferably 8 or more from the viewpoint of promoting the loading of copper on low-grade coal, and is preferably 11 or less from the viewpoint of suppressing the production of copper hydroxide. More preferably, it is in the range of 9-10.

  The low-grade coal is generally defined as coal having a calorific value of 5,000 kcal / kg or less, and occupies half of coal resources. Specific examples include lignite (carbonization degree 70% to 78%), lignite (carbonization degree 70% or less), peat (carbonization degree 60% or less), and the like. Low-grade coal has many oxygen-containing functional groups such as hydroxy groups and carboxy groups as compared with coal having a high carbonization degree. It is thought that these oxygen-containing functional groups act as ion exchange groups and copper is supported on low-grade coal.

The low-grade coal is preferably particulate. The lower limit of the particle diameter is not particularly limited, and the volume average particle diameter is preferably 30 μm or more and more preferably 45 μm or more from the viewpoint of suppressing the decrease in handleability due to aggregation. The upper limit of the particle size of the low-grade coal is not particularly limited, and can be selected according to, for example, a desired particle size of copper oxide particles described later. The volume average particle diameter can be measured by classification using a sieve.
The content of low-grade coal in the mixture is not particularly limited. From the viewpoint of the copper loading of the low-grade coal, it is preferably 10% by mass or more, and more preferably 20% by mass or more.
The low-grade coal may remove surface impurities in advance. Specific examples include a method of washing with hydrochloric acid.

  The nitrogen atom-containing compound is not particularly limited as long as it can form a complex with copper. It is considered that the loading of copper on low-grade coal is promoted by the nitrogen atom-containing compound forming a complex with copper in the mixture. Specific examples include compounds having an amino group such as ammonia and primary to tertiary amines; compounds having an amide group; quaternary ammonium cations such as choline. From the viewpoint of complex formation with copper, compounds having amino groups such as ammonia and primary to tertiary amines are preferred. The said nitrogen atom containing compound may be used individually by 1 type, or may use 2 or more types.

  The content of the nitrogen atom-containing compound in the mixture is not particularly limited. For example, it is preferable that it is the content rate from which the pH in 25 degreeC of the said mixture becomes the range of 8-11, and it is more preferable that it is the content rate in which pH in 25 degreeC becomes 9-10.

  The mixture may contain components other than the low-grade coal and the nitrogen atom-containing compound. Examples of other components include water, organic solvents, and components such as chlorine ions and sulfate ions contained in a waste liquid containing copper ions. The concentration of copper ions in the mixture is not particularly limited.

  The copper recovery method may include a step of stirring the mixture in order to promote loading of copper on low-grade coal. Conditions such as the stirring method, temperature and time are not particularly limited. For example, it can be performed using a stirrer at room temperature (25 ° C.) for 10 to 60 minutes.

  The step of taking out the low-grade coal supported by copper from the mixture is not particularly limited, and can be performed by a general method such as filtration. For example, it can be performed using a membrane filter with a suction filter.

  By heat-treating the low-grade coal supported by copper taken out from the mixture, the low-grade coal is decomposed and disappears, and copper can be recovered in the form of copper oxide. The temperature of the heat treatment is preferably low from the viewpoint of suppressing energy consumption. The present inventors have found that low-grade coal carrying copper is decomposed at a lower temperature than low-grade coal not carrying copper. The reason for this is presumed to be that the copper supported on the low-grade coal acts as a catalyst and promotes the decomposition of the low-grade coal at a low temperature. Therefore, according to the method of the present invention, low-grade coal can be decomposed and copper can be recovered at a temperature lower than that of conventional techniques such as a sintering method.

  In this regard, Japanese Patent Application Laid-Open No. 2008-248363 adds a low-grade coal particle such as a basic aqueous solution and lignite to an electroless nickel plating waste liquid as a method for recovering a metal from a waste liquid containing metal ions, and converts the nickel into a low-grade coal particle. A method of carrying and heat-treating is known. However, the tendency for the low-grade coal carrying nickel to decompose at a temperature lower than the decomposition temperature of the low-grade coal not carrying nickel has not been confirmed.

  The upper limit of the temperature of the heat treatment can be, for example, 600 ° C. or less, preferably 500 ° C. or less, and more preferably 300 ° C. or less. The lower limit of the temperature of the heat treatment may be a temperature at which the low-grade coal carrying copper is sufficiently decomposed, and is preferably set to, for example, 150 ° C. or higher. The time for the heat treatment is not particularly limited, and can be, for example, in the range of 60 minutes to 180 minutes. The method for the heat treatment is not particularly limited, and can be performed using, for example, a general dryer.

<Method for producing copper oxide>
The method for producing copper oxide of the present invention comprises preparing a mixture containing at least a copper ion, a low-grade coal, and a nitrogen atom-containing compound capable of forming a complex with copper, and the low-grade coal supporting copper on the mixture. And a step of heat-treating the low-grade coal extracted from the mixture. Specific examples and preferred embodiments of the respective components contained in the mixture, and specific examples and preferred embodiments of the respective steps are the same as those in the above-described copper recovery method.

  The copper oxide obtained by the above method can be reduced and used as metallic copper. The reduction method is not particularly limited, and a commonly used method can be used. For example, copper can be obtained by hydrogen reduction.

  The copper oxide is usually recovered in the form of particles. In this case, the particle size of the copper oxide tends to increase as the particle size of the low-grade coal increases. Therefore, by adjusting the particle size of the low-grade coal, copper oxide having a desired particle size can be obtained. The particle diameter of the copper oxide is not particularly limited, and can be selected, for example, from the range of 45 μm to 2000 μm in volume average particle diameter.

<Example>
Hereinafter, the present invention will be described in detail by way of examples. However, this invention is not restrict | limited at all by these Examples. “%” Is based on mass.

[Example 1]
Ammonia water was added to a waste solution containing copper ions (hydrochloric acid 10%, copper ion concentration 30 g / L), and the pH at 25 ° C. was adjusted to 8. Next, 100 g of brown coal (produced by Loy-Yang, Australia, volume average particle size adjusted within the range of 45 μm to 74 μm) is added to 1 L of pH adjusted waste liquid, and the mixture is stirred for 10 minutes to perform static sedimentation. It went for 30 minutes or more. Then, the lignite supporting copper was taken out from the waste liquid using a membrane filter with a suction filter. The copper-supported lignite was heat treated for 180 minutes in a 250 ° C. drying furnace, and the residue was recovered. The evaluation was performed by measuring the copper loading rate of the copper to the brown coal, the recovery rate of the residue, and the copper content rate in the residue by the method described later. The evaluation results are shown in Table 2.

Industrial analysis values and elemental analysis values of the lignite are as shown in Table 1 below.

[Example 2]
Except that the pH of the waste liquid at 25 ° C. was adjusted to 11, the same steps as in Example 1 were performed, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 2.

[Example 3]
The same process as in Example 1 was performed except that the pH of the waste liquid at 25 ° C. was adjusted to 9.5 and the heat treatment was performed in a drying furnace at 400 ° C. for 180 minutes, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 2.

[Example 4]
The same process as in Example 1 was carried out except that the pH of the waste liquid at 25 ° C. was adjusted to 9.5 and the heat treatment was performed in a drying furnace at 150 ° C. for 180 minutes, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 2.

[Comparative Example 1]
The same processes as in Example 1 were performed except that ammonia water was not added to the waste liquid, and the same evaluation as in Example 1 was performed. The pH of the waste liquid at 25 ° C. was 1 or less. The evaluation results are shown in Table 2. In addition, even if the lignite extracted from the waste liquid was heat-treated under the same conditions as in Example 1, the lignite was not decomposed and 100 g remained.

[Comparative Example 2]
Except that lignite was not added to the waste liquid and the pH at 25 ° C. was adjusted to 9.5, the same steps as in Example 1 were performed, and the same evaluation as in Example 1 was performed. Note that 64 g of copper chloride remained after the heat treatment. The evaluation results are shown in Table 2.

(Evaluation of copper loading on lignite)
The loading ratio of copper on lignite was measured as follows. That is, the lignite with copper supported is dried at 90 ° C. for 1 hour, and then its mass (M1) is measured. Next, the lignite supporting the copper is mixed with a mixed acid (volume ratio of hydrochloric acid 3: nitric acid 1) to dissolve copper, and the copper concentration in the dissolved mixed acid is measured with an atomic absorption meter, and the mass of copper (M2) Is calculated. The copper loading rate (%) of lignite is calculated by the following calculation formula 1.

(Evaluation of recovery rate of remaining part)
The recovery rate of the residue was measured as follows. That is, the lignite with copper supported is dried at 90 ° C. for 1 hour, and then its mass (M1) is measured. Subsequently, after heat-treating under the conditions described in each Example, the mass (M3) of the recovered residue is measured. The remaining recovery rate (%) is calculated by the following calculation formula 2.

(Evaluation of copper content in the remainder)
The copper content in the collected residue was measured as follows. That is, after measuring the mass (M3) of the recovered residue, this residue was dissolved with a mixed acid (hydrochloric acid 3: nitric acid 1 by volume), and then the copper concentration was measured with an atomic absorption photometer to measure the mass of copper (M4 ) Is calculated. The copper content in the residue is calculated by the following calculation formula 3. The copper content in the residue being close to 80.0% means that the ratio of copper oxide in the residue is close to 100%, and the lignite has been sufficiently decomposed by heat treatment.

As shown in Table 2, the copper loading of the low-grade coal in Examples 1 to 4 exceeded 9%. Moreover, the content rate of copper in the collect | recovered residue was 80.0%, and it turned out that the brown coal has decomposed | disassembled substantially by heat processing.
In Comparative Example 1 in which ammonia water was not added to the waste liquid, the loading ratio of copper to lignite was 0.0%. Moreover, even if it heat-processed on the same conditions as Example 1, lignite remained without decomposing | disassembling. In Comparative Example 2 in which lignite was not added to the waste liquid, copper chloride remained after the heat treatment. In this case, the copper recovery rate is small and copper chloride remains, so that it is difficult to recover only copper.

Claims (4)

A step of preparing a mixture containing at least a copper ion, a low-grade coal, and a nitrogen atom-containing compound capable of forming a complex with copper, a step of taking out the low-grade coal carrying copper from the mixture, and taking out of the mixture wherein the step of heat treating the low-grade coal, only including, the temperature of the heat treatment is 250 ° C. or less, the recovery method of copper. The copper recovery method according to claim 1 , wherein the mixture further contains water. The method for recovering copper according to claim 1 or 2 , wherein the pH of the mixture at 25 ° C is in the range of 8 to 11. A step of preparing a mixture containing at least a copper ion, a low-grade coal, and a nitrogen atom-containing compound capable of forming a complex with copper, a step of taking out the low-grade coal carrying copper from the mixture, and taking out of the mixture wherein the step of heat treating the low-grade coal, only including, the temperature of the heat treatment is 250 ° C. or less, the manufacturing method of copper oxide.