JP2009226302A - Method for treating waste printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating a waste printed circuit board by which the waste printed circuit board is efficiently treated and further is changed to more worthy valuables. <P>SOLUTION: The method for treating the waste printed circuit board includes a first process where the waste printed circuit board which is roughly crushed in advance and used as a raw material, is charged into a rotary kiln, and heated with superheated steam so as to carbonize the part except included metals, a second process where the waste printed circuit board treated in the first process is crushed to obtain the powder containing carbonized products and ceramics and other particulates consisting of metals, and a third process for separating the particulates from the powder, produced in the second process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for treating a waste printed circuit board generated in large quantities from waste home appliances, communication devices, computers, or the like.

Since the waste printed board contains a noble metal such as copper, gold, silver, and palladium, it is useful as a resource. Therefore, for example, as described in Patent Document 1, the waste printed circuit board is put into an acid such as nitric acid, hydrochloric acid, sulfuric acid or the like, and as described in Patent Document 2, the waste printed circuit board is crushed and burned with a burner. A method for separating the combustible material and recovering the metal has been proposed.
Patent Document 3 proposes that a waste printed circuit board is placed in a thermal decomposition chamber and heated in a steam atmosphere and in an oxygen-free state to recover the metal.

Japanese Patent Laid-Open No. 11-36020 JP 2000-104126 A JP 2003-290755 A

However, the method of treating a waste printed board using an acid as described in Patent Document 1 takes time, and it is difficult to continuously treat the waste printed board, and the waste liquid is expensive to process. It was.
Further, in the method of treating the waste printed circuit board described in Patent Document 2 by combustion, the precious metal contained in minute amounts is easily scattered, the recovery rate of the precious metal is lowered, and a large amount of harmful gas such as dioxin is generated. There was a problem that processing equipment was necessary.

Therefore, there was a method of recovering valuable metals by pulverizing waste printed circuit boards with a shearing machine and crushing machine, and performing electrostatic sorting, magnetic sorting, eddy current sorting, etc. Since the total amount of the metal does not change, there is a problem that the processing efficiency is poor. Moreover, the metal contained in the waste printed circuit board was strongly bonded to the plating and the resin, and the accuracy of single metal separation was poor even when pulverized.
On the other hand, in the method described in Patent Document 3, since the main part of the waste printed circuit board is carbonized using high-temperature steam, the metal recovery rate is high, but since it is batch processing, the processing efficiency is low. was there. Further, there has been no disclosure about the treatment after carbonizing the waste printed circuit board using high temperature steam.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for treating a waste printed board that efficiently treats the waste printed board and converts the waste printed board into a valuable material with higher value.

A method for treating a waste printed board according to the first invention in accordance with the first object is to put a waste printed board, which is a raw material roughly crushed in advance, into a rotary kiln and heat it using superheated steam, and a part other than the contained metal A first step of carbonizing,
A second step of crushing the waste printed circuit board processed in the first step to form a powder comprising carbide and ceramics and a granular material made of other metals;
It has the 3rd process which isolate | separates the granular material produced | generated at the said 2nd process, and powder.

In addition, about this rotary kiln, what is described in patent 3602504 can be used, for example. Thus, by processing with a rotary kiln, volume reduction processing of a waste printed circuit board can be performed in large quantities and continuously. By performing the carbonization treatment of the waste printed board, the weight of the waste printed board is reduced to 0.25 to 0.37, so that the subsequent treatment can be performed even in a batch type.

The waste printed circuit board processing method according to the second invention is the waste printed circuit board processing method according to the first invention, wherein the processed material in the first step is oxygen-free on the discharge side of the rotary kiln. Cooling means for cooling and discharging in the state is provided. As a result, combustion of the carbonized waste printed board and oxidation of the contained metal can be prevented, and the metal recovery efficiency is improved.

A waste printed circuit board processing method according to a third invention is the waste printed circuit board processing method according to the first and second inventions, wherein the waste printed circuit board is a biaxial shear crusher or an impact crusher. Roughly crushed to 10 cm or less. The size of the waste printed circuit board to be crushed is 10 cm or less in order to smoothly process with a rotary kiln, for example, with a screw conveyor, etc. (More preferably, 5 cm or 3 cm or less).

A waste printed circuit board processing method according to a fourth invention is the waste printed circuit board processing method according to the first to third inventions, wherein the temperature of the superheated steam is in the range of 350 to 800 ° C., and the processing time is 5-60 minutes.
Here, if the temperature of the superheated steam is less than 350 ° C., the thermal decomposition of the plastics in the waste printed circuit board does not proceed and it is difficult. When the temperature of the superheated steam exceeds 800 ° C., there is no serious problem, but the loss of heat energy increases. Furthermore, the problem of the heat resistance of an apparatus arises. Therefore, the temperature of the superheated steam is preferably about 400 to 700 ° C and more preferably about 420 to 600 ° C.

A waste printed circuit board processing method according to a fifth aspect of the present invention is the waste printed circuit board processing method according to any of the first to fourth aspects of the invention, wherein the crushing of the second step involves separating glass fiber materials contained by an impact crusher. And a grinding step of further grinding the crushed material crushed by the impact crusher with a ball mill or a rod mill. Thereby, even if a glass epoxy material is used for the printed circuit board, the glass fiber after being heated to remove the resin can be finely pulverized, and the laminated copper foil can be recovered. Of the base materials used for the waste printed circuit board, the glass epoxy resin is discharged in a state in which the glass woven fabric maintains its shape during carbonization. In this woven glass fabric, the glass fiber does not fall apart and the laminated copper foil cannot be collected by a milling type grinder. Also, with impact-type crushers, the glass fibers fall apart and the copper foil to be laminated can be collected, but the glass fibers are not finely pulverized and the fibers aggregate to form cotton, which is used during classification. Inhibits.

A waste printed circuit board processing method according to a sixth aspect of the present invention is the waste printed circuit board processing method according to the fifth aspect of the present invention, wherein the weight of the granular material is A and the weight of the powder is B. Assuming that the price per unit weight of the granular material and the powder that varies depending on the value is P and Q, the maximum value of AP + BQ is in the range of 0.97 to 1 for the same weight of raw material. Adjusting the time of the grinding step.

In other words, precious metals (gold, silver, palladium) contained in the waste printed circuit board are often attached in a plated state to metals such as copper. When applied to a grinding machine (for example, a ball mill or a rod mill) for a long time, the precious metal attached to the metal moves to the powder side, and when the time applied to the grinding machine is short, it remains on the particulate side. On the other hand, since the sales price of granular materials and powder varies depending on the amount of metal (usually noble metal) contained, the price to sell the final product granular materials and powder is AP + BQ, and the processing time of the grinder In the end, it is preferable to manufacture the product by controlling the grinding time. The target is brought close to the maximum value of AP + BQ. That is, the reason why the maximum value is in the range of 0.97 to 1 is that the final price varies depending on the type of the waste printed circuit board, and it is difficult to always make the maximum value.

The waste printed circuit board processing method according to any one of claims 1 to 6, wherein the waste printed circuit board, which is a raw material roughly coarsely crushed in advance, is placed in a rotary kiln and heated with high-temperature superheated steam to carbonize portions other than the metal. 1 step, 2nd step of crushing the waste printed circuit board processed in the 1st step, and making it the granular material which consists of the powder and the other thing which includes carbide and ceramics, it was produced in the 2nd step Since it has a third step of separating the granular material and the powder, the metal contained in the waste printed board is prevented from being oxidized, and is contained in the final product powder and granular material. The recovery efficiency is improved.

Furthermore, the processing facilities can be reduced and the processing time can be shortened as compared with the case where the waste printed circuit board is acid-treated. Further, the amount of gas generated is smaller than that in the case of combustion treatment, and the generated gas has a small amount of dioxin and contains oil, so that it can be recovered as fuel or other resources.
Furthermore, since it is a continuous process using a rotary kiln, the heat treatment of the waste printed circuit board can be performed continuously, and the processing time can be shortened and the processing amount can be increased.

The waste printed circuit board processing method according to claim 2 is provided with cooling means for cooling and discharging the processed material in the first step in an oxygen-free state on the discharge side of the rotary kiln, so that the metal is oxidized. In addition, since the amount of flight due to a flame or the like is reduced, the metal recovery rate is improved and the problem of environmental pollution due to the discharged metal is also reduced.

The waste printed circuit board processing method according to claim 3, wherein the waste printed circuit board is roughly crushed to 10 cm or less using a biaxial shear crusher or an impact crusher, so that it is transported or processed in a rotary kiln. And subsequent handling becomes easy.

In the method for treating a waste printed board according to claim 4, since the temperature of the superheated steam is 350 to 800 ° C. and the treatment time is 5 to 60 minutes, the waste printed board can be carbonized with a small heat source. Is not heated to a high temperature, and continuous operation is possible.

The waste printed circuit board processing method according to claim 5, because the carbonized waste printed circuit board is crushed by an impact crusher before being applied to a grinder, so that a substrate made of glass epoxy remains in the waste printed circuit board. Even if it is, the glass fiber after carbonization can be loosened and broken apart by impact, and the efficiency of the grinding treatment can be increased.

The waste printed circuit board processing method according to claim 6, wherein the weight of the granular material is A, the weight of the powder is B, and the price per unit weight of the granular material and the powder varies depending on the contained metal. In the case of P and Q, the grinding process time is adjusted so that the raw material of the same weight is within the range of 0.97 to 1 of the maximum value of AP + BQ. It is possible to sell waste printed circuit board processing products at a higher price than sales.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
FIG. 1 is a flowchart showing a waste printed circuit board processing method according to an embodiment of the present invention.

As shown in FIG. 1, waste printed circuit boards are collected from various places (step S1). There are various types of waste printed boards, such as power boards, communication circuit boards, and PC boards, but there are also large ones, so about 10 cm (more preferably 5 cm, more preferably with a biaxial shear crusher or impact crusher). More preferably, it is roughly crushed to 3 cm) or less (step S2). As a biaxial shear crusher, for example, as described in JP-A-7-155630, JP-A-2002-355575, JP-A-2005-270838, etc., two crushing members are provided. There are those that are arranged with their axes facing each other, and a waste printed circuit board is placed in an intermediate position to be crushed.

Thereafter, the roughly crushed waste printed board is subjected to a magnetic separator to remove magnetic deposits (mainly iron), and then to an eddy current separator to remove copper and aluminum debris. In this case, it is preferable that the magnetic field of the magnetic separator and the eddy current separator is appropriately reduced so that iron, aluminum and copper to which the resin is adhered are not removed. That is, it is preferable to select in advance only a single metal such as iron, copper, or aluminum. Since this process is optional, it is not shown in FIG.

Next, the roughly crushed waste printed circuit board is placed in a rotary kiln and heated at 350 to 800 ° C. using superheated steam as a heat source for 5 to 60 minutes. As the rotary kiln, for example, the one described in Japanese Patent No. 3602504 is used (step S3). Japanese Patent No. 3602504 discloses a first rotary kiln for drying a processed raw material, and a second rotary kiln for subjecting a processed raw material dried by the first rotary kiln to a dry distillation process using high-temperature superheated steam. However, since the waste printed circuit board is usually dry, only the second rotary kiln is used. This heating is preferably performed in an oxygen-free or diluted oxygen state (for example, 5% by volume or less, preferably 3% by volume or less, and further 1% by volume or less) in the rotary kiln.

The discharge mechanism of this rotary kiln (second rotary kiln in the same patent) has a discharge screw conveyor (an example of a cooling means), and the processed raw material is flowed from the inlet side of this discharge screw conveyor. In addition, the superheated steam or saturated steam filled in the rotary kiln is caused to flow through the screw conveyor to be in an oxygen-free state. And when it is humidified and comes out of the exit of the screw conveyor for discharge | emission in the process which is flowing through the inside of a screw conveyor, it is cooled to 100 degrees C or less.

Thereby, after the treated carbide is discharged, it is not reburned and the heated metal is not oxidized. Further, since there is no metal oxidation even in the rotary kiln, it hardly flies as an oxide. As a result, most of the metal contained in the waste printed board can be recovered. In addition, when the roughly crushed waste printed circuit board, which is a raw material in a rotary kiln, is pyrolyzed, for example, 60 to 70% by mass becomes volatiles with respect to the whole (waste printed circuit board 100%), and the remaining 30 to 40 mass % Is recovered.

In the process of step S3, a large amount of exhaust gas is generated, but since it is processed with high-temperature steam, the generation of dioxin is reduced. Gas with a high calorific value can be obtained, and there is also a part that liquefies and becomes oil. Therefore, the exhaust gas can be used effectively as a fuel.

The processed product (carbonized waste printed circuit board) discharged from the rotary kiln (specifically, the screw conveyor for discharge) is crushed by an impact crusher, and the sieve etc. is +0.5 mm min. .Classified to 5 mm. As this impact crusher, for example, a rotary impact crusher described in Japanese Patent No. 2909503 (RIM in Examples described later) can be used. As a result, in addition to the crushing effect, the effect of rounding the shape of the metal can be added, so that the metal (copper wire or the like) does not pierce the mesh during subsequent sieving, and the efficiency can be increased.
Here, +0.5 mm portion refers to a sieved product when sieved with a sieve having an opening degree (opening) of 0.5 mm, and −0.5 mm component refers to a sieved product (accordingly, powder). Glass fibers remain even if the substrate such as glass epoxy resin is steamed and baked in a rotary kiln. However, when crushed by this impact crusher, the fiber components fall apart (step S4, crushing step). In addition, the +0.5 mm portion is a granular material mainly containing metals.

Next, the +0.5 mm granular material, that is, the crushed product is ground (pulverized) by a pulverizer such as a pole mill or a rod mill. As a result, the ceramics contained in the granular material, the glass formed into a cotton shape in the crushing process, or the fibrous glass is also powdered (step S5, grinding process). Next, classification is performed using a sieve or the like, and the product is classified into a +0.5 mm sieved product (granular material) and a -0.5 mm sieved product (powder) (step S6). In addition, the granular material here includes not only a lump but also a flat shape.
By this pulverization treatment, carbides, glass and ceramics adhering to the periphery of the metal are also almost completely removed, and most of the particulate matter (for example, 80% or more) becomes a metal component.

Thereafter, the granular material is applied to a magnetic separator to remove the magnetized metal (step S7), and further applied to an eddy current separator to select a highly conductive metal such as copper or aluminum and other metals (step S8). In this embodiment, a sieve having an opening degree of 0.5 mm is used for classification, but it is preferable to use a sieve having an opening (classification point) of about 0.1 to 0.8 mm.

In step S5, when the treatment time is lengthened, more precious metals such as gold, silver, and palladium move to the powder side. This is because these precious metals are joined by being plated on a base metal (for example, copper or a copper alloy), so in the stage of crushing with an impact crusher etc. However, when grinding with a ball mill or the like is continued, it gradually peels off and moves to the powder side.

The price of the powder and the granular material varies depending on the content of the noble metal. In addition, if the pulverization by the ball mill is continued, the operation cost increases and the price on the granule side also decreases. Therefore, considering these points, the processed product (powder and granular material) has the maximum price. It is preferable to do so. The powder (mainly carbide) generated in Steps S4 and S5 is shipped after granulation and molding in consideration of subsequent handling (Step S9).

Next, examples performed to confirm the operation and effect of the present invention will be described.
When the raw material just before putting into the rotary kiln of step S3 of FIG. 1 was 100 mass%, the recovered material (processed material) was 36.3% by mass, and the volatile matter was 63.7 mass%. When this recovered material is subjected to the crushing and classification processes in steps S4 and S5, the +0.5 mm sieved product (granular material) is 22.3% by mass, and the −0.5 mm sieved product (powder). Was 14% by mass. Table 1, Table 2, and Table 3 show industrial analysis of the noble metals, ordinary metals, and powders in these granular materials and powders.

In Table 3, [T. C] represents the total carbon content, [VM] represents the volatile matter, and [T-Cl] represents the total chlorine content.

Next, Table 4 shows the distribution on the sieve and under the sieve, the quality, the evaluation price, and the sales when the crushing conditions and the grinding conditions are changed in the steps S4, S5, and S6. Sales are prices converted per ton of raw material.

In Table 4, (1) RIM-1 and (2) RIM-2 represent a processed product discharged from the rotary kiln (components are different in each case) and a rotary impact crusher (for example, Japanese Patent No. 2909503). The crushing time is about 15 minutes for RIM-1 and about 30 minutes for RIM-2. Longer time increases the amount of sieving and the amount of precious metal under the sieving also increases. In (3), the processed product is pulverized only by a ball mill. (4) and (5) are processed by RIM-1 and RIM-2 and then pulverized by a ball mill. In addition, the ball mill uses iron balls and the processing time is 15 minutes.

As is clear from the above experiments, when the pulverization and pulverization are made longer, more noble metals such as Au and Ag move to the powder side. The evaluation price varies depending on the contents of copper and noble metals. When the weight of the granular material is A, the weight of the powder is B, and the prices per unit weight of the granular material and the powder that vary depending on the metal contained are P and Q, It is preferable to set the maximum value of AP + BQ. Since it is difficult to find the maximum value, it is preferable to adjust the time of the grinding (pulverization) step so that the maximum value is in the range of 0.97 to 1.

It is a flowchart of the processing method of the waste printed circuit board which concerns on one embodiment of this invention.

Claims (6)

A first step of putting a waste printed circuit board, which is a raw material roughly crushed in advance, into a rotary kiln, heating it with superheated steam, and carbonizing a part other than the contained metal,
A second step of crushing the waste printed circuit board processed in the first step to form a powder comprising carbide and ceramics and a granular material made of other metals;
A method for treating a waste printed circuit board, comprising: a third step of separating the granular material generated in the second step and the powder. The waste printed circuit board processing method according to claim 1, wherein a cooling means for cooling and discharging the processed material in the first step in an oxygen-free state is provided on the discharge side of the rotary kiln. A method for processing waste printed circuit boards. The waste printed circuit board processing method according to any one of claims 1 and 2, wherein the waste printed circuit board is roughly crushed to 10 cm or less using a biaxial shear crusher or an impact crusher. A method for treating a waste printed circuit board. The waste printed circuit board processing method according to any one of claims 1 to 3, wherein the temperature of the superheated steam is in the range of 350 to 800 ° C, and the processing time is 5 to 60 minutes. To process waste printed circuit boards. The waste printed circuit board processing method according to any one of claims 1 to 4, wherein the crushing of the second step includes a crushing step of separating glass fiber materials contained by an impact crusher, and the impact crushing. And a grinding process of grinding the crushed material crushed by a machine with a ball mill or a rod mill. The waste printed circuit board processing method according to claim 5, wherein the weight of the granular material is A, the weight of the powder is B, and the granular material varies according to the metal contained and per unit weight of the powder. Waste printing characterized by adjusting the time of the grinding process so that the maximum value of AP + BQ is in the range of 0.97 to 1 for raw materials of the same weight when the prices are P and Q Substrate processing method.

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