TWI486312B - Process for recovering copper from copper-containing waste liquid - Google Patents

Description

Method for recovering copper from copper-containing waste liquid

The invention provides a method for recovering copper from a copper-containing waste liquid, in particular, a method for preparing a copper-containing compound, in particular copper carbonate and copper oxide, from the copper-containing waste liquid to achieve copper recovery and reuse.

The rapid development of industrialization has brought many conveniences to life for mankind. However, a large amount of industrial waste is also produced. With the rise of environmental awareness, how to reduce or effectively recycle and reuse waste generated in various industries has become a hot topic.

The main sources of copper-containing waste are metal industry, electronics industry, and chemical manufacturing. The copper-containing wastes produced by the booming electronics industry (such as the printed circuit board industry) include acid copper etching waste liquid and alkaline copper etching waste liquid.

A method for treating an acidic copper-containing waste liquid in the technical field comprises: producing a copper metal precipitate by an aluminum displacement method; or adding a sodium hydroxide to neutralize the waste liquid, and causing copper ions in the waste liquid to precipitate as copper hydroxide or copper oxide. A method for treating an alkaline copper-containing waste liquid in the technical field includes recovering copper by a sulfide precipitation method; or generating a recyclable copper oxide by heating and alkali aeration. However, if the above method is not limited by the cost problem, the obtained product has a high impurity content, or there are other impurities which are not easily treated, which are present in the process or in the recovered product.

In view of this, the present invention provides an effective copper recovery method to solve the above problems. The method of the invention can greatly reduce the impurity content, so that a versatile copper source can be selected, and the operation is convenient and economical, and the recovered copper can be prepared into a copper-containing compound having reusable value (for example, copper hydroxide, Copper oxide or copper carbonate), and the copper-containing compound can be made into various grades as needed, including an electronic grade that requires strict impurities, which is not only highly flexible but also meets the current environmental trends.

In one aspect, the invention provides a method for recovering copper from a copper-containing waste liquid, comprising:

(a) adding a precipitant to the copper-containing waste liquid, adjusting the pH to a range of about 2 to about 9, allowing impurities to precipitate and removing impurities, and controlling the copper ion concentration to be less than 120 g/liter;

(b-1) A copper-containing compound is prepared from the solution obtained in the step (a). Another aspect of the invention provides a method of recovering copper from a copper-containing waste liquid, comprising:

(a) adding a precipitant to the copper-containing waste liquid, adjusting the pH to a range of about 2 to about 9, allowing impurities to precipitate and removing impurities, and controlling the copper ion concentration to be less than 120 g/liter;

(b-2) The pH of the solution obtained in the controlling step (a) is in the range of from about 3 to about 13, and precipitates to produce copper hydroxide or a copper salt mixture containing copper hydroxide.

According to still another aspect of the present invention, a method for producing copper carbonate or copper oxide from copper hydroxide or a copper salt mixture containing copper hydroxide, comprising:

(c) adding an acid to copper hydroxide or a copper salt mixture containing copper hydroxide, and dissolving it into an acidic copper-containing solution;

(d-1) adding a carbonate to the acidic copper-containing solution prepared in the step (c), controlling the pH in the range of about 6 to about 7 to form copper carbonate;

(e) converting copper carbonate prepared in the step (d-1) into copper oxide by a conversion reaction as needed.

The source of the copper-containing waste liquid used in the present invention is not particularly limited, and may be wastes recovered from various industries or daily life, such as, but not limited to, acidic or alkaline copper-containing waste liquid, acidic or alkaline copper etching waste liquid. , electroplating waste liquid, copper-containing sludge or metal copper scrap. For example, the acidic copper-containing waste liquid comprises a copper solution of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, phosphoric acid or acetic acid or a combination thereof, and the alkaline copper-containing waste liquid comprises a copper ammonium salt of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, phosphoric acid or acetic acid. Solution or a combination thereof. The collected copper waste liquid or waste material may be pretreated in any manner familiar to those skilled in the art to which the present invention pertains, for example, to increase the copper ion content in the copper waste liquid by acid replacement, and to acid or alkali. The impregnation method dissolves copper from the copper-containing sludge to form a copper-containing waste liquid, or dissolves the copper waste with an acid or an alkali to form a copper-containing waste liquid, so that the copper content in the copper-containing waste liquid is not too low. For example, the copper content in the copper-containing waste liquid should be higher than 10 g/l. According to the present invention, when copper content in the copper-containing waste liquid is low, solid copper such as copper powder, copper foil, copper scrap, copper ore, copper sludge, copper alloy or other copper scrap or a combination thereof may be added to improve Process efficiency. In addition, if the product to be prepared is a compound containing divalent copper, it is also possible to form a divalent copper ion by a redox method by using one of the copper ions in the waste liquid as needed.

In general, copper-containing waste liquids may contain various metal ions such as tin, lead, zinc, iron, calcium, magnesium, etc. in addition to copper ions. The presence of these metal ions increases the difficulty of conventional copper recycling processes. However, the inventors of the present invention have found that in the step of preparing a copper-containing compound from a copper-containing waste liquid, a specific precipitating agent is added to the copper-containing waste liquid as appropriate, and the acid is appropriately added to the alkaline copper-containing waste liquid or added. Alkali to acidic copper-containing waste liquid or a combination thereof to adjust the pH value of the waste liquid, can precipitate a plurality of metal impurities, and then remove the precipitated impurities through a separation step such as filtration, thereby effectively purifying the copper-containing waste liquid and reducing The proportion of metal impurities that are not desired in the waste liquid to control the copper ion concentration is suitable for the appropriate range of subsequent processes. This purification step can first remove unwanted metal impurities such as tin, lead, zinc, calcium, magnesium, manganese, etc., so that the steps required to remove such impurities in subsequent processes can be omitted and the The effect of impurities on the process. In addition, the purification step does not adversely affect the copper ions present in the solution, and can effectively purify the copper-containing waste liquid and reduce the proportion of undesired metal impurities in the waste liquid, thereby improving the recovery and recovery. The purity of the copper compound.

Therefore, the method of the present invention is used in the procedure for preparing a copper-containing compound by first using a purification step as described above to remove unwanted metal impurities in the copper-containing waste liquid. In particular, the purification step is the addition of a specific precipitant (including but not limited to nitric acid, sulfuric acid, hydrochloric acid, tartaric acid, acetic acid, phosphoric acid, ammonium chloride, oxalic acid, sulfide, sodium hydroxide, potassium hydroxide, sodium carbonate, carbonic acid Potassium or ammonia or a mixture thereof) to a copper-containing waste liquid, adjusting the pH to a range of about 2 to about 9, preferably a pH of about 2 to about 6, to precipitate impurities and remove impurities, and control copper ions The concentration is below 120 g/L, and the preferred concentration range is below 80 g/L. The amount of the precipitating agent used in the present invention has no fixed range, and can be adjusted according to the amount of the impurity according to the necessity. When the amount of the impurities is large, the amount of the precipitating agent also needs to be increased. For example, in an embodiment using a generally normal waste liquid, a precipitant having a concentration ranging from about 0.2 to about 5 wt% can be used. The acid and the base for adjusting the pH value of the waste liquid are not particularly limited, and may be acids and bases commonly used in the art. For example, the acid may include nitric acid, sulfuric acid, hydrochloric acid, tartaric acid, acetic acid, phosphoric acid, ammonium chloride, oxalic acid or As a mixture thereof, the base may include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or ammonia or a mixture thereof.

In accordance with the present invention, it may be desirable to remove impurities after such purification steps, in a manner well known to those of ordinary skill in the art to which the present invention pertains. For example, it is desirable to remove calcium or magnesium ions with an ion exchange resin; or to remove organic impurities with activated carbon; or to add an oxidizing agent such as chlorate, hypochlorite, perchlorate, H ₂ O ₂ , Air or oxygen or a combination thereof removes metal ions such as iron ions. The concentration of the above oxidizing agent is in the range of from about 0.005 to about 20% by weight, preferably from about 0.01 to about 0.5% by weight. Preferably, the oxidizing agent is a hypochlorite such as sodium hypochlorite.

The process of the present invention can be used to prepare a copper-containing compound having reusable value by any of the methods known to those skilled in the art after the above purification step, using the purified copper-containing waste liquid. The copper-containing compound is not particularly limited, and is preferably copper hydroxide, copper carbonate or copper oxide. Copper carbonate as used herein refers to copper carbonate in a broad sense, that is, a copper carbonate product well known to those of ordinary skill in the art to which the present invention pertains, for example, including basic copper carbonate, CuCO ₃ ‧Cu(OH) ₂ compound, Bronze and so on.

Two embodiments of the method for recovering copper from a copper-containing waste liquid of the present invention are further described below with reference to FIGS. 1 and 2, but are not intended to limit the scope of the present invention. Modifications and variations that may be readily made by those skilled in the art of the present invention are included in the scope of the present specification and claims.

Fig. 1 shows a first embodiment of the method for recovering copper from a copper-containing waste liquid of the present invention, and the copper-containing compound obtained in this embodiment is copper carbonate or copper oxide. As shown in FIG. 1, the method of the present invention firstly purifies copper-containing waste liquid, and then prepares copper carbonate or copper oxide by spray drying.

In particular, according to a first embodiment of the present invention, the present invention provides a method for recovering copper from a copper-containing waste liquid, comprising:

(a) adding a precipitant to the copper-containing waste liquid, adjusting the pH to a range of about 2 to about 9, preferably at a pH of about 2 to about 6, to precipitate impurities and remove impurities, and to control the concentration of copper ions. Below 120 g / liter, the preferred concentration range is below 80 g / liter; and

(b-1) The solution obtained in the step (a) is prepared by spray drying to prepare copper carbonate or copper oxide.

The preparation of copper carbonate or copper oxide by spray drying is well known to those of ordinary skill in the art, and the detailed steps can be found in the disclosure of U.S. Patent 3,607,023.

According to the present invention, the variation of the first embodiment described above includes: when the product obtained in the step (b-1) is copper carbonate, it can be converted into copper oxide by a conversion reaction as needed. The above transformation reaction can be any one of ordinary skill in the art to which the present invention pertains. For example, copper carbonate can be heated to a suitable temperature (for example, 200 to 500 ° C) in a sufficient oxygen atmosphere to react with oxygen to form copper oxide, and can be filtered, washed, and dried as needed. Become a specific copper oxide product.

2 is a second embodiment of the method for recovering copper from a copper-containing waste liquid of the present invention. The method of the present invention firstly purifies the copper-containing waste liquid, and then performs a neutralization step to precipitate copper hydroxide or Copper salt mixture of copper hydroxide.

In particular, according to a second embodiment of the present invention, the present invention provides a method for recovering copper from a copper-containing waste liquid, comprising:

(a) adding a precipitant to the copper-containing waste liquid, adjusting the pH to a range of about 2 to about 9, preferably at a pH of about 2 to about 6, to precipitate impurities and remove impurities, and to control the concentration of copper ions. Below 120 g / liter, the preferred concentration range is below 80 g / liter; and

(b-2) The pH of the solution obtained in the controlling step (a) is in the range of from about 3 to about 13, and precipitates to produce copper hydroxide or a copper salt mixture containing copper hydroxide.

Since there may be other unremoved ions in the copper-containing waste liquid, such as ammonium ions, chloride ions, etc., the copper hydroxide prepared in the second aspect step (b-2) may be in the form of a copper salt mixture. There are, for example, Cu(OH) ₂ ‧CuCl ₂ or Cu(OH) ₂ ‧Cu(NH ₃ ) ₄ Cl ₂ or the like.

The pH adjustment of the above step (b-2) can be carried out by mixing the acidic copper-containing waste liquid obtained after the purification step with the alkaline copper-containing waste liquid in an appropriate ratio, or by adding an acid or a base. The acid and the base are not particularly limited, and may be an acid or a base commonly used in the art. For example, the acid may include nitric acid, sulfuric acid, hydrochloric acid, tartaric acid, acetic acid, phosphoric acid, ammonium chloride or oxalic acid or a combination thereof, and the alkali may include Sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or ammonia or a combination thereof.

In order to improve the utilization efficiency of the copper-containing product, the present invention further provides a method for preparing copper carbonate or copper oxide from copper hydroxide or a copper salt mixture containing copper hydroxide. The above copper hydroxide or copper hydroxide-containing copper salt mixture can be obtained by the method for recovering copper from the copper-containing waste liquid of the present invention (for example, the second embodiment described above), or can be obtained by any conventional method.

In particular, the present invention provides a method for preparing copper carbonate or copper oxide from copper hydroxide or a copper salt mixture containing copper hydroxide, comprising:

(c) adding an acid to copper hydroxide or a copper salt mixture containing copper hydroxide, and dissolving it into an acidic copper-containing solution;

(d-1) adding a carbonate to the acidic copper-containing solution prepared in the step (c), controlling the pH in the range of about 6 to about 7 to form copper carbonate;

(e) converting copper carbonate prepared in the step (d-1) into copper oxide by a conversion reaction as needed.

The acid used in the above step (c) is not particularly limited, and is preferably a mineral acid such as hydrochloric acid, sulfuric acid or nitric acid or a combination thereof. The amount of the acid to be added or the pH of the solution is not particularly limited as long as it is added in an amount sufficient to completely dissolve the solid copper compound (for example, copper hydroxide) in the acidic copper-containing solution. The conversion reaction of the above step (e) is as previously described herein.

The carbonate used in the above step (d-1) includes, but is not limited to, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium hydrogencarbonate or the like or a combination thereof, preferably sodium carbonate or potassium carbonate. In detail, the carbonation reaction step is carried out by contacting the copper-containing acidic solution obtained by the above step (c) with an alkali carbonate, and appropriately adjusting the addition ratio of the sodium carbonate to control the pH in the range of about 6 to about 7. .

Preferably, the inventors have found that prior to performing step (d-1), a small amount of the copper-containing acidic solution may be quickly mixed (or premixed) with the carbonate. In this fast mixing, there is no specific limit to the temperature. Since the fast mixing can be carried out before carrying out the step (d-1) of the present invention, the present invention can prepare copper carbonate at a lower pH range, thereby reducing the amount of alkali to be added for controlling the pH, thereby The quality of the resulting product can be controlled; in addition, since the fast mixing can be carried out at a lower temperature range, energy consumption in the process can be saved.

In addition, the present invention may optionally add copper carbonate crystal grains as seed crystals in the above step (d-1) to form step (d-3) to accelerate the formation of copper carbonate crystals, wherein the weight of the added copper carbonate particles is between It is in the range of about 0.005 to 5 wt%, preferably about 0.01 to 0.1 wt%. The above seed crystals may be selected from those commonly used in the art, such as, but not limited to, basic copper carbonate. Preferably, the reaction time of the crystal growth reaction is at least about 20 to about 60 minutes, and the control temperature is in the range of from about 30 ° C to about 70 ° C, preferably in the range of from 50 ° C to about 60 ° C.

3 is a schematic view showing a method of preparing copper carbonate or copper oxide from a copper hydroxide or copper salt-containing copper salt mixture of the present invention.

4 is a schematic view showing a method for preparing copper hydroxide or a copper salt mixture containing copper hydroxide from a copper-containing waste liquid of the present invention, and then preparing copper carbonate or copper oxide through the same.

The invention further provides a method for preparing copper oxide from copper hydroxide or a copper salt mixture containing copper hydroxide. This method can further prepare copper hydroxide or a copper salt mixture containing copper hydroxide prepared according to the present invention (for example, the second embodiment described above) as copper oxide. In detail, this method includes:

(c) adding an acid to copper hydroxide or a copper salt mixture containing copper hydroxide to dissolve it into an acidic copper-containing solution;

(d-2) adding a base to the acidic copper-containing solution prepared in the step (c), controlling the pH in the range of from about 9 to about 14, preferably from about 12 to about 14, and controlling the temperature to about 80. The range of from ° C to about 105 ° C, preferably in the range of from about 90 ° C to about 100 ° C, produces copper oxide. The type of the base to be added is not particularly limited, and sodium hydroxide is preferred.

Figure 5 is a schematic view showing a method for preparing copper oxide or a copper salt mixture containing copper hydroxide from copper-containing waste liquid according to the present invention, thereby preparing copper oxide by first preparing copper hydroxide or hydrogen by the method of the present invention. Copper salt mixture of copper oxide.

The following examples are intended to illustrate the invention and are not intended to limit the scope of the invention. Modifications and variations that may be readily made by those skilled in the art are included within the scope of the disclosure of the present disclosure and the scope of the appended claims.

Example 1

Add phosphoric acid to the alkaline copper-containing waste liquid (copper content is 99.38 g / liter), adjust the pH value between about 2 to about 6, do not want metal ions will react with phosphate to form insoluble phosphates, so that impurities Precipitate and filter to remove impurities. The content of impurities in the copper-containing liquid and the raw liquid after purification is as shown in Table 1 below:

It can be seen from the data in the table that the addition of phosphoric acid to the copper-containing waste liquid can precipitate a plurality of metal impurities, which is beneficial for removing unwanted metal impurities, purifying the copper-containing waste liquid, and effectively reducing the proportion of undesired metal impurities in the waste liquid.

Example 2

Adding acidic copper-containing waste liquid (copper content: 31.43 g / liter) with sodium hydroxide, adjusting the pH to about 4.2 to precipitate impurities, and then adding 0.5 wt% of sodium hypochlorite to continue the precipitation, and filtering to remove impurities. The content of impurities in the copper-containing liquid and the raw liquid after purification is as shown in Table 2 below:

According to the data in the table, adjusting the pH value and adding oxidant to the alkaline copper-containing waste liquid can precipitate a variety of metal impurities, which is beneficial to remove unwanted metal impurities, purify the copper-containing waste liquid, and effectively reduce the waste liquid. The proportion of metal impurities desired.

1 is a first embodiment of a method for recovering copper from a copper-containing waste liquid of the present invention.

2 is a second embodiment of the method for recovering copper from a copper-containing waste liquid of the present invention.

3 is a schematic view showing a method of preparing copper carbonate or copper oxide from a copper hydroxide or copper salt-containing copper salt mixture of the present invention.

4 is a schematic view showing a method for preparing copper hydroxide or a copper salt mixture containing copper hydroxide from a copper-containing waste liquid of the present invention, and then preparing copper carbonate or copper oxide through the same.

5 is a schematic view showing a method for preparing copper oxide by preparing a copper hydroxide or a copper salt mixture containing copper hydroxide from a copper-containing waste liquid of the present invention.

(no component symbol description)

Claims (20)

A method for recovering copper from a copper-containing waste liquid, comprising: (a) adding a precipitant to a copper-containing waste liquid, adjusting a pH to a range of about 2 to about 6, precipitating impurities and removing impurities, and controlling copper ions The concentration is below 80 g/L; and (b-2) the pH of the solution obtained in the control step (a) is in the range of from about 3 to about 13, and precipitation produces copper hydroxide or a copper salt mixture containing copper hydroxide. The method of claim 1, further comprising, after the above step (a), at least one purification step selected from the group consisting of: purification with an ion exchange resin, purification with activated carbon, and purification with an oxidizing agent. The method of claim 2, wherein the concentration of the oxidizing agent is in the range of from about 0.005 to about 20% by weight. The method of claim 2, wherein the oxidizing agent comprises chlorate, hypochlorite, perchlorate, H ₂ O ₂ , air or oxygen, or a combination thereof. The method of claim 4, wherein the oxidizing agent is sodium hypochlorite. The method of claim 1, wherein the precipitating agent comprises nitric acid, sulfuric acid, hydrochloric acid, tartaric acid, acetic acid, phosphoric acid, ammonium chloride, oxalic acid, sulfide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or ammonia or a combination thereof. . The method of any one of claims 1 to 6, further comprising the step of: (c) adding an acid to the copper hydroxide or copper hydroxide-containing copper salt mixture prepared in the step (b-2), Dissolved into an acidic copper-containing solution. The method of claim 7, wherein the acid of step (c) is hydrochloric acid, sulfuric acid or nitric acid or a combination thereof. The method of claim 7, further comprising the steps of: (d-1) adding a carbonate to the acidic copper-containing solution prepared in the step (c), controlling the pH in the range of about 6 to about 7 to form copper carbonate; and (e) optionally converting by a reaction The copper carbonate prepared in the step (d-1) is converted into copper oxide. The method of claim 9, wherein the carbonate of step (d-1) is sodium carbonate, potassium carbonate, ammonium carbonate, ammonium hydrogencarbonate or the like or a combination thereof. As in the method of claim 9, the copper carbonate particles may be added as seed crystals in the above step (d-1), wherein the weight of the added copper carbonate particles is between about 0.005 and 5 wt%, and the reaction time is from about 20 to about 60. In minutes, the temperature is controlled to range between about 30 ° C and about 70 ° C. The method of claim 7, further comprising the step of: (d-2) adding a base to the acidic copper-containing solution prepared in the step (c) to form copper oxide. The method of claim 12, wherein the base of step (d-2) is sodium hydroxide. The method of claim 12, wherein the pH of step (d-2) is controlled in the range of from about 9 to about 14. The method of claim 12, wherein the temperature of step (d-2) is controlled to range between about 80 ° C to about 105 ° C. The method of claim 1, wherein the copper source of the copper-containing waste liquid comprises an acidic copper-containing waste liquid, an alkaline copper-containing waste liquid, solid copper or a mixture thereof. The method of claim 16, wherein the acidic copper-containing waste liquid comprises a copper solution of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, phosphoric acid or acetic acid or a combination thereof; the alkaline copper-containing waste liquid comprises hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, phosphoric acid or vinegar The acid copper ammonium salt solution or a combination thereof; and the solid copper comprises copper powder, copper foil, copper scrap, copper ore, copper sludge or copper alloy or a combination thereof. The method of claim 1, further comprising the step of: (c) adding an acid to the copper hydroxide or a copper salt mixture containing copper hydroxide to dissolve it into an acidic copper-containing solution. (d-3) adding a carbonate to the acidic copper-containing solution prepared in the step (c), controlling the pH in the range of about 6 to about 7, and adding copper carbonate particles as a seed crystal, wherein the copper carbonate particles are added The weight is between about 0.005 and 5 wt% of the reaction time of about 20 to about 60 minutes, the control temperature is in the range of between about 30 ° C and about 70 ° C to form copper carbonate; and (e) as needed by a conversion reaction The copper carbonate prepared in the step (d-3) is converted into copper oxide. The method of claim 18, wherein the acid of step (c) is hydrochloric acid, sulfuric acid or nitric acid or a combination thereof. The method of claim 18, wherein the carbonate of step (d-3) is sodium carbonate, potassium carbonate, ammonium carbonate, ammonium hydrogencarbonate or a combination thereof.