JP4147246B2 - Method for recovering metallic copper from waste liquid containing copper chloride - Google Patents

Description

    The present invention relates to a method for recovering metallic copper from a factory waste liquid containing copper chloride, and more particularly to a method for recovering metallic copper from an etching waste liquid used in the manufacturing process of a printed wiring board or the like.

Since the copper component is contained in the form of copper chloride in the waste liquid of the etching solvent used in the etching process of the printed wiring board, etc., the copper chloride is recovered as metallic copper from the recovered waste liquid of the etching solvent. Several techniques for regenerating an etching solution have been proposed.

  As one of the methods for recovering metallic copper from the recovered etching solvent waste liquid, conventionally, for example, a sulfuric acid solution is added to a copper chloride solution and concentrated to recover dilute hydrochloric acid. After recovering dilute hydrochloric acid, copper sulfate crystals and copper sulfate are recovered. In this technique, a mixture of aqueous solutions is diluted with water and the aqueous solution after the crystals are dissolved in the dilution step is electrolyzed to recover metallic copper. (See Patent Document 1)

  Also proposed is a solution in which copper chloride-containing etching waste liquid is mixed with an alkaline liquid having a pH of 9 or more, and an oxidizing agent is added to the liquid mixture to precipitate dissolved copper ions to recover copper. (See Patent Document 2)

Furthermore, the ferric chloride etching waste liquid containing a large amount of nickel and copper is added with small pieces or lump metal iron to reduce the remaining ferric chloride to ferrous chloride, and the concentration of copper ions in the waste liquid. That deposits copper to 10 ppm or less, adds iron powder to the reduced liquid, precipitates and removes nickel, oxidizes the denicked liquid and regenerates it to ferric chloride Has also been proposed. (Patent Document 3)
JP 2002-327288 A JP 2002-255550 A Japanese Patent No. 2657795

  However, each of the conventional devices has to be equipped with large-scale equipment and machinery, which increases the equipment cost, requires a large number of man-hours, and increases the cost for recovering copper metal. was there.

  This invention pays attention to such a point, and it aims at providing the method of collect | recovering metallic copper with high purity by a simple process.

  In order to achieve the above-mentioned object, the present invention is a muddy iron-water mixture in which iron powder is further pulverized by a pulverizer and the pulverized iron powder and water are kneaded to form a muddy iron-water mixture. A stirring reaction step in which the muddy iron-water mixture is added to the copper chloride-containing waste liquid obtained by recovering the waste liquid of the ferric chloride solution containing copper chloride, and stirred to react; In addition to discharging the ferrous chloride solution produced in step 1, the discharge step of taking out the precipitate precipitated at the bottom to the pulverizer, and pulverizing the precipitate charged in the pulverizer in a hydrochloric acid solution having a pH of 4 or less It is characterized by comprising a metallic copper separation step for separating metallic copper and a rinsing step for washing out the extracted metallic copper.

  In the present invention, a slurry-like iron water mixture obtained by kneading iron powder finely pulverized by a pulverizer and water is charged into a copper chloride-containing waste liquid and stirred so that ferric chloride in the waste liquid is iron. It reacts violently with powder and heat generation to become ferrous chloride, and cupric chloride in the waste liquid reacts with iron powder to release chlorine ions to become metallic copper, and iron powder is released to chlorine ions. To ferrous chloride. At this time, however, the metallic copper adheres to the surface of the iron powder coating, so the iron powder adhering to the metallic copper is cracked in the metallic copper on the surface by grinding it in the presence of hydrochloric acid with a grinder The metal copper is separated by causing the internal iron powder and hydrochloric acid to act to dissolve the iron content, and the metal copper is washed with water, whereby high-purity metal copper can be recovered.

Hereinafter, the method of the present invention will be described based on one embodiment. FIG. 1 is a flowchart showing the procedure of the method of the present invention.
Copper chloride is contained together with the ferric chloride solution and the ferrous chloride solution in the waste liquid of the etching solvent used in the etching process of the printed wiring board and the like. The copper chloride-containing waste liquid is recovered (step S1).

  On the other hand, as a pre-treatment stage, iron powder is put into a rotating drum type pulverizer to make a fine powder until it becomes powdery iron powder (step S2). This finely powdered iron powder is put into a stirring and mixing tank, and water is added and stirred and mixed to form a slurry-like mixture (a mud-like iron-water mixture). (Step S3) Here, the fine powder pulverized and formed by the pulverizer has a particle size enough to pass through a sieve of 60 to 350 mesh. The addition of iron powder in a slurry is to reduce reaction unevenness and speed up the reaction, and the iron powder and water are in a volume ratio of about 1: 1 to 1: 1.5. Stir and mix.

  The above-described copper chloride-containing waste liquid is poured into a stirring tank, the muddy iron water mixture is sequentially added, and stirring and mixing are performed while maintaining the temperature in the stirring tank at about 15 ° C. By adding and stirring the slurry-like iron water mixture into the copper chloride-containing waste liquid, ferric chloride in the copper chloride-containing waste liquid and iron powder in the slurry-like iron-water mixture react exothermically to become ferrous chloride. The copper chloride in the copper chloride-containing waste liquid and the iron powder in the muddy iron water mixture undergo a substitution reaction to change to ferrous chloride and metallic copper. At this time, metallic copper exists in the state which adhered to the state which coats the surface of the iron powder in a muddy iron-water mixture. (Step S4)

  Then, when the chlorine component involved in the reaction in the copper chloride-containing waste liquid is consumed and the reaction with the iron powder is stopped, the introduction of the mud iron water mixture is stopped. The stirring is stopped after the stirring is continued for several minutes (for example, 10 minutes) even after the introduction of the muddy iron-water mixture is stopped. (Step S5)

After the stirring is stopped, the stirring tank is allowed to stand for a predetermined time (for example, 1 hour). (Step S6)
By this standing, the iron powder whose surface is coated with metallic copper precipitates at the bottom of the stirring tank, and the liquid in the stirring tank becomes a ferrous chloride solution. While sucking out this ferrous chloride solution with a pump, the iron powder coat | covered with the copper settled and accumulated in the bottom part of a stirring tank is taken out to a grinder. (Step S7)

  In the pulverizer, hydrochloric acid is added to the iron powder coated with copper, and the iron powder coated with copper is crushed while maintaining the hydrogen index of the liquid in the pulverizer at pH 4 or less, preferably in the range of pH 1 to 3. To do. This crushing causes cracks in the coated copper, and hydrochloric acid penetrates into the coated copper from this crack and reacts with iron powder and other metals in the coated copper to remove iron and other metals (impurities). , Isolate the copper metal. At this time, the carbon taken in along with the iron powder and the like floats on the liquid surface in the pulverizer by stirring accompanying crushing. (Step S8)

The metallic copper separated in the hydrochloric acid bath is taken out as metallic copper after passing through a rinsing step (step S9) in which the hydrochloric acid is discharged and then washed with purified water after tap water. (Step S10)
Here, the rinsing with tap water is for economic reasons, and the rinsing with purified water as a final step is to prevent the adhesion of impurities.

  In addition, the metal copper separation process in step S8 and the rinsing process in step S9 are repeated several times until the supernatant becomes colorless, thereby increasing the purity of the recovered metal copper to 98% or more. it can.

  In the above implementation procedure, the iron powder is pulverized into a fine powder as the pretreatment stage, but as the iron powder in this case, the iron powder obtained as a result of the shot blasting work is used, but the polishing work Or the chip-like iron powder obtained by grinding operation may be crushed. In addition, iron powder or chip-like iron powder may be washed with a surfactant and water to remove oil and then pulverized into a fine powder.

  Also, at the end of the rinsing process, when the hydrogen index of the treated water reaches about pH 7, if the treated product (metal copper) is left in the tap water or purified water for a predetermined time and then discharged, Since the residual liquid of ferrous iron becomes an iron hydroxide solution and dissolves in the supernatant, the purity of the extracted metallic copper can be further improved.

  INDUSTRIAL APPLICATION This invention can be utilized for what collect | recovers metallic copper from the ferrous chloride waste liquid used for the etching of copper plates including the etching of a printed circuit board.

It is a flowchart which shows the procedure of this invention method.

Claims (2)

A muddy iron water mixture creating step in which the iron powder is further finely pulverized by a pulverizer, and the fine powdered iron powder and water are kneaded to form a muddy iron water mixture
A stirring reaction step of adding the muddy iron-water mixture to the copper chloride-containing waste liquid obtained by recovering the waste liquid of ferric chloride liquid containing copper chloride, and stirring and reacting;
A discharge step of discharging the ferrous chloride solution generated by the stirring reaction and taking out the precipitate precipitated at the bottom to a pulverizer,
A metal copper separation step of separating the metal copper by pulverizing the precipitate charged in the pulverizer in a hydrochloric acid solution having a pH of 4 or less;
A rinsing step of washing out the extracted copper metal,
A method for recovering metallic copper from a waste liquid containing a copper chloride-containing factory. The method for recovering metallic copper from a copper chloride-containing factory waste liquid according to claim 1, wherein the metallic copper separation step and the rinsing step are repeated.

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