Method for Removing Bromine Compounds from Copper-Containing Recycling Raw Materials and Purifying Copper

Abstract

To provide a method for removing a bromine compound from a copper-containing recycling raw material and purifying copper.SOLUTION: By performing low-temperature pyrolysis on copper-containing recycling materials that contain copper and bromine compounds, bromine compounds are separated into hydrogen bromide gas and copper-containing powder awaiting processing. The hydrogen bromide gas reacts with metal oxides to form solid metal bromine compounds. By conducting thermal purification treatment on the copper powder awaiting processing, the copper within is melted and transformed into liquid copper, yielding a molten metal containing impurities. A slag remover is added to form a slag phase layer that rises above the liquid copper, due to the substances other than liquid copper in the molten metal and the slag remover. Finally, by removing the slag phase layer, the liquid copper is separated and refined into high-purity copper.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the treatment of electronic waste, and particularly to a method for treating copper-containing recycling raw materials derived from discarded printed circuit boards.

Background Art

[0002] Discarded printed circuit boards contain substances such as copper foil, resin, glass fiber cloth, and brominated flame retardants. Recycling and reusing discarded printed circuit boards as resources is an important issue at present. In particular, how to recover copper from discarded printed circuit boards and how to avoid the pollution problem caused by brominated flame retardants contained in discarded printed circuit boards are highly regarded.

[0003] For example, Patent Document 1 discloses a method for promoting the dechlorination of organic bromine compounds in a liquid product generated by thermally decomposing a non-metallic fraction containing a brominated flame retardant of an electronic substrate in a steam atmosphere added with iron. Further, Patent Document 2 discloses a method for recovering valuable metals from powder of discarded electronic circuit boards, in which a tin alloy liquid, a lead-based alloy liquid, a zinc-aluminum-copper alloy liquid, and a crude copper liquid are sequentially separated from the powder of discarded electronic circuit boards by using gradually increased heating temperatures and a supergravity separation technique.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Accordingly, an object of the present invention is to newly provide a method for removing a bromine compound from a copper-containing recycling raw material and purifying copper.

Means for Solving the Problems

[0006] To achieve the above object, the present invention performs low-temperature pyrolysis on a copper-containing recycling raw material containing copper and a bromine compound to separate it into hydrogen bromide gas formed by the bromine compound and copper powder to be treated containing the copper, reacts the hydrogen bromide gas with a metal oxide to form a solid of a metal bromine compound, and performs a heat purification treatment on the copper powder to be treated to melt the copper in the copper powder to be treated and change it into liquid copper to obtain a molten metal containing impurities, provides a method for removing a bromine compound from a copper-containing recycling raw material and purifying copper, in which a slag removing agent is added to the molten metal to form a slag phase layer floating on the liquid copper by a substance other than the liquid copper in the molten metal and the slag removing agent, and then the slag phase layer is removed to separate the liquid copper.

Effects of the Invention

[0007] The method of the present invention can not only convert a bromine compound into a solid of a non-polluting or non-dangerous metal bromine compound, but also recover copper from a copper-containing recycling raw material to obtain high-purity copper.

Brief Description of the Drawings

[0008]

Figure 1

Embodiments for Carrying Out the Invention

[0009] The following will describe in detail one embodiment of a method for removing a bromine compound from a copper-containing recycling raw material of the present invention and purifying copper with reference to the drawings.

[0010] FIG. 1 is a flowchart showing a method for removing a bromine compound from a copper-containing recycling raw material of the present invention and purifying copper.

[0011] As shown in the figure, first, a low-temperature thermal decomposition treatment is performed on a copper-containing recycling raw material containing copper and a bromine compound to separate it into hydrogen bromide gas formed by thermal decomposition of the bromine compound and copper powder to be treated containing the copper. Examples of the bromine compound include, but are not limited to, brominated flame retardants such as tetrabromobisphenol A epoxy resin. More specifically, the copper-containing recycling raw material is obtained by performing a recycling treatment on a discarded printed circuit board, and the recycling treatment includes selecting a waste material containing copper as the copper-containing recycling raw material from a large amount of waste materials obtained by pulverizing the discarded printed circuit board. Since the discarded printed circuit board originally contained copper foil, resin, glass fiber cloth, brominated flame retardant, etc., the copper-containing recycling raw material contains glass fiber cloth and resin in addition to the copper and the brominated flame retardant. Incidentally, according to the low-temperature thermal decomposition treatment, the bromine compound can be changed into hydrogen bromide gas instead of brominated dioxin. In this example, the low-temperature thermal decomposition treatment is performed on the copper-containing recycling raw material in a fluidized bed reactor. Specifically, the low-temperature thermal decomposition treatment is performed in a temperature range of 300°C to 500°C. When the copper-containing recycling raw material and the copper powder to be treated were analyzed using a fluorescent X-ray analyzer, the percentage of copper in the copper-containing recycling raw material was 80%, the percentage of bromine was 0.0326%, and the percentage of bromine in the copper powder to be treated was 0.0073%.

[0012] Then, by reacting the hydrogen bromide gas with a metal oxide, the hydrogen bromide gas is decomposed and a solid of a metal bromine compound is formed by the metal oxide. More specifically, the metal oxide is iron sand, which contains ferric oxide. When the solid of the metal bromine compound was analyzed using an X-ray diffractometer, it was found that the solid of the metal bromine compound contained iron(II) bromide.

[0013] Then, by performing a heat purification treatment on the copper powder awaiting treatment, the copper in the copper powder awaiting treatment is melted to be changed into liquid copper to obtain a molten metal containing impurities. More specifically, since the glass fiber cloth and the resin are further included in the copper-containing recycled raw material, in the heat purification treatment, the resin is thermally decomposed and the glass fiber cloth is melted into glass slag, so that the molten metal further contains the glass slag and the substances obtained by thermal decomposition of the resin. In this embodiment, the heat purification treatment uses the induction melting method in an air induction melting device to melt the copper in the copper powder awaiting treatment at a temperature of 1200 °C or higher to make it liquid copper. More specifically, the copper is melted within a temperature range of 1200 °C to 1700 °C.

[0014] Then, a slag removing agent is added to the molten metal to form a slag phase layer by the substances other than the liquid copper in the molten metal and the slag removing agent, and since the slag phase layer floats on the liquid copper, removing the slag phase layer means separating the liquid copper. Examples of the slag removing agent include metal oxides such as CaO, MgO, and SiO2, and common slag removing agents such as cryolite (Na3AlF6) or sodium tetraborate (Na2B4O7). However, it is not limited to these, and the slag removing agent can be selectively used according to the actual content of the molten metal. All the slag removing agents used in the present invention are commercially available products. In this example, as a result of performing component analysis using a scanning electron microscope (SEM) and an energy dispersive X-ray analysis (EDS) system together, it was found that the components of the slag phase layer included a CaO-SiO2-MgO-(Al2O3) composite phase composed of calcium oxide (CaO), silicon dioxide (SiO2), magnesium oxide (MgO), and aluminum oxide (Al2O3). And when the liquid copper was analyzed using an inductively coupled plasma spectroscopic analyzer, it was found that the percentage of copper in the liquid copper was 99.7%. Therefore, compared with the fact that the percentage of copper in the copper-containing recycled raw material was 80%, the percentage of copper contained in the liquid copper was clearly improved, which proved that the present invention can purify high-purity copper from the copper-containing recycled raw material.

[0015] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to this, and various modifications can be made without departing from the gist thereof.

Claims

1. By subjecting a copper-containing recycling raw material containing copper and a bromine compound to low-temperature pyrolysis, it is separated into hydrogen bromide gas formed by the bromine compound and copper powder to be processed containing the copper. The hydrogen bromide gas is reacted with a metal oxide to form a solid of a metal bromine compound, and by performing a heat purification treatment on the copper powder to be processed, the copper in the copper powder to be processed is melted and changed into liquid copper to obtain a molten metal containing impurities. A slag remover is added to the molten metal to form a slag phase layer floating on the liquid copper by a substance other than the liquid copper in the molten metal and the slag remover, and then the slag phase layer is removed to separate the liquid copper. The copper-containing recycling raw material further contains a glass fiber cloth and a resin, and the copper-containing recycling raw material is obtained by performing a recycling treatment on a discarded printed circuit board. The recycling treatment includes selecting a waste material containing copper as the copper-containing recycling raw material from waste materials obtained by pulverizing the discarded printed circuit board. A method for removing a bromine compound from a copper-containing recycling raw material and purifying copper, characterized in that it is included.

2. The method for removing a bromine compound from a copper-containing recycling raw material and purifying copper according to claim 1, wherein the low-temperature pyrolysis treatment is performed in a temperature range of 300°C to 500°C.

3. The method for removing a bromine compound from a copper-containing recycling raw material and purifying copper according to claim 1, wherein the percentage of bromine in the copper powder to be processed is 0.0073% or less.

4. The method for removing a bromine compound from a copper-containing recycling raw material and purifying copper according to claim 1, wherein the bromine compound is a bromine-based flame retardant.

5. The method for removing a bromine compound from a copper-containing recycling raw material and purifying copper according to claim 1, wherein the metal oxide is iron sand.

6. The method for removing a bromine compound from a copper-containing recycling raw material and purifying copper according to claim 1, wherein the solid of the metal bromine compound contains iron(II) bromide.

7. In the heating and purification treatment, the method for removing bromine compounds from the copper-containing recycled raw material according to claim 1 and purifying copper, characterized in that the copper in the copper powder to be treated is heated to 1200 °C or higher and melted into liquid copper by using an induction melting method.

8. In the heating and purification treatment, the method for removing bromine compounds from the copper-containing recycled raw material according to claim 1 and purifying copper, characterized in that the copper in the copper powder to be treated is heated within a temperature range of 1200 °C to 1700 °C and melted into liquid copper by using an induction melting method.

9. In the components of the slag phase layer, CaO - SiO ２ -MgO-(Al ２ O ３ ) composite phase is included, and the method for removing bromine compounds from the copper-containing recycling raw material according to claim 1 and purifying copper is characterized by this.

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