JPH0718023B2 - Copper sulfate recovery method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for etching an electric circuit board such as a printed wiring board by precipitating copper dissolved in an etching solution as crystals of copper sulfate pentahydrate by a cooling crystallization method. The present invention relates to a collecting method and an apparatus thereof.

[0002]

2. Description of the Related Art In manufacturing an electric circuit board such as a printed wiring board, an etching solution containing hydrogen peroxide and sulfuric acid or a mixed acid as a main component is used to remove a specific amount of copper or copper alloy. The etching process is performed while maintaining the temperature at about 45 to 50 ° C. In this etching solution,
Since copper melts and accumulates during use, in order to recover the excess without decomposing residual hydrogen peroxide,
This etching solution was cooled in a crystallization can and collected as crystals having a water temperature of copper sulfate of 5 (hereinafter simply referred to as copper sulfate). By the way, the copper sulfate crystals to be recovered are preferably in a state with as little liquid content as possible, and the copper sulfate slurry is taken out from the crystallizer and transferred to a solid-liquid separator to recover the copper sulfate crystals with less liquid content. It is preferable that the separated liquid component be returned to the etching step and reused as an etching liquid. However, the liquid that is returned to the etching process after the copper sulfate is recovered will continue to precipitate crystals even during the return process, and it may not be possible to force-return by the pump due to blockage of crystals in the return pipe, etc. It is known, for example, from Japanese Utility Model Application Laid-Open No. 64-7266 that the solution is once received in an intermediate tank, heated and then returned to the etching step. However, a heating means cannot be applied to the copper sulfate slurry transferred from the crystallizer to the solid-liquid separator due to the subsequent crystal recovery operation, and the copper sulfate slurry outlet of the crystallizer or In many cases, copper sulfate crystals were grown and precipitated also in the transfer pipe, and the outlets, transfer pipes, valves, etc. of these were blocked, making it impossible to transfer the copper sulfate slurry.

[0003]

DISCLOSURE OF THE INVENTION The present invention is directed to a solution in a copper sulfate recovery system for clogging of a copper sulfate slurry outlet of a crystallizer or a copper sulfate slurry transfer pipe to a solid-liquid separator with copper sulfate crystals. It is an object of the present invention to provide a method and an apparatus for effectively recovering copper sulfate and smoothly recovering copper sulfate.

[0004]

According to the present invention, crystals of copper sulfate pentahydrate are broken out by introducing an etching solution in which copper is dissolved into a crystallization can and cooling it, and sulfuric acid is discharged from the lower outlet of the crystallization can. In the method for recovering copper sulfate, the copper pentahydrate salt slurry is taken out and transferred to a solid-liquid separator to recover copper sulfate pentahydrate crystals, and the separated liquid is heated in an intermediate tank and returned to the etching step. Washing of the copper sulfate pentahydrate slurry transfer passage between the crystallizer and the solid-liquid separator and backwashing of the copper sulfate pentahydrate slurry outlet of the crystallizer are performed by the warming liquid in the intermediate tank. And a copper sulphate pentahydrate slurry outlet of a crystallizer for cooling and precipitating copper dissolved in an etching solution as crystals of copper sulphate pentahydrate by a transfer pipe. It is connected to the separator, and the separated liquid outflow part of the solid-liquid separator is connected to the etching tank. The intermediate tank for heating is further connected to the intermediate tank for heating via a washing pump so that the liquid in the intermediate tank for heating is supplied into the transfer pipe between the crystallizer and the solid-liquid separator. It is a copper sulfate recovery device characterized by being connected together.

[0005]

When the etching solution used in the etching process, in which copper is dissolved in a high concentration, is introduced into the crystallization can and cooled to about 15 ° C. with stirring, the copper dissolved in the solution is sulfuric acid having a uniform particle size. Precipitates as copper crystals and settles at the bottom of the crystallizer. The precipitated copper sulfate crystals are discharged together with the liquid as copper sulfate slurry from the outlet of the crystallizer, transferred to the solid-liquid separator through the transfer pipe, and the copper sulfate crystals are separated and recovered (see FIG. 2). On the other hand, the separated liquid separated by the solid-liquid separator once reaches the intermediate tank and is heated to a temperature of 30 to 40 ° C. and is smoothly returned to the etching step without observing the precipitation of crystals.
Since the etching process is performed at a temperature of about 45 to 50 ° C., it can be heated to a temperature suitable for the etching process in the intermediate tank. When such copper sulfate recovery is performed, the copper sulfate slurry outlet of the crystallizer and the transfer pipe to the solid-liquid separator are gradually blocked by the copper sulfate crystals, so the copper sulfate slurry flows out from the transfer pipe. Knowing the cleaning time by decreasing the amount, stop the transfer of copper sulfate slurry, and supply the heated etching solution in the intermediate tank into the transfer pipe to return the etching solution to the intermediate tank while cleaning the inside of the tube. When it is circulated, the inside of the pipe is effectively cleaned in a short time (Fig. 3).
reference). Regarding the copper sulfate slurry outlet of the crystallizer,
Cleaning is performed by backwashing in which the heated etching liquid in the intermediate tank is intermittently backflowed (see FIG. 4). When the cleaning of these transfer pipes and the backwashing of the crystallization can outlet are completed, the copper sulfate recovery operation is started again.

[0006]

EXAMPLE An example of the present invention will be described with reference to FIG. 1. Reference numeral 1 is a crystallization can for cooling and crystallizing copper sulfate crystals, and a stirrer or the like (not shown) is provided therein. The liquid in the can is cooled by the refrigerant sent from the chiller 2. An outlet 3 for copper sulfate slurry is provided at the bottom of the crystallization can 1 and is opened and closed by a slurry extraction valve 4. The slurry extraction valve 4 is connected to a centrifugal separator 8 by a transfer pipe 7 equipped with a slurry extraction pump 5, a backwash valve 6, and the like. The separated liquid outflow portion 9 of the centrifuge 8 is connected to the intermediate tank 10, and a heater such as an electric heater (not shown) is provided in the intermediate tank 10 to heat the liquid in the tank. The intermediate tank 10 is connected to the transfer pipe 7 via a cleaning pipe 13 including a cleaning pump 11, a cleaning valve 12 and the like. In addition, the intermediate tank 10 has an etching tank 15 via a return pump 14.
The overflow tank 16 connected to the pump 1 receives the etching solution overflowing from the etching tank 15
It is connected to the crystallization can 1 by a pipe 18 provided with 7.

Therefore, in this embodiment, the temperature is 45
The etching solution used in the etching tank 15 under the condition of ˜50 ° C., in which copper is dissolved in a high concentration, overflows to the overflow tank 16 and is guided to the crystallization can 1 by the pump 17 through the pipe 18 and the pipe 18. The etching liquid introduced into the crystallization can 1 is cooled to a temperature of 15 ° C. by a coolant such as brine sent from the chiller 2, and the copper dissolved in the liquid becomes copper sulfate crystals to form a crystal in the crystallization can 1. Settle to the bottom. At the high level (H level) of the crystallizer 1,
The slurry extraction valve 4 is opened, the centrifuge 8 is started, the slurry extraction pump 5 is operated, and the precipitated copper sulfate crystals are transferred together with the liquid as copper sulfate slurry from the outlet 3 to the centrifugal separator 8 via the transfer pipe 7. Then, the liquid is separated and copper sulfate crystals are recovered. The above crystal separation path is shown by the shaded area in FIG. The separated liquid separated by the centrifuge 8 is guided from the separated liquid outflow portion 9 to the intermediate tank 10, heated to a temperature of 30 to 40 ° C., and then smoothly returned to the etching tank 15 by the return pump 14 for etching. It is reused as a liquid.

While the above copper sulfate recovery operation is continued, the amount of copper sulfate slurry flowing out from the transfer pipe 7 decreases. If there is no abnormality in the equipment in the copper sulfate slurry transfer route, it is determined that copper sulfate crystals have accumulated in the outlet 3 of the crystallizer 1 and the transfer pipe 7, and these are cleaned. That is, when the liquid level of the crystallization can 1 is low (L level), the slurry extraction valve 4 is closed and the slurry extraction pump 5 is stopped.
Then, the washing valve 12 is opened to operate the washing pump 11,
The etching liquid at 30 to 40 ° C. in the intermediate tank 10 is supplied from the cleaning pipe 13 into the transfer pipe 7, and the crystals in the transfer pipe 7 are dissolved and allowed to flow out to the centrifuge 8 again.
And the transfer pipe 7 is washed for a certain period of time. The above-mentioned cleaning path of the transfer pipe 7 is shown by the hatched portion in FIG. After cleaning the transfer pipe 7, the backwash valve 6 is closed and the slurry extraction valve 4 is opened / closed, whereby the etching solution in the intermediate tank 10 intermittently flows back through the outlet 3, and the slurry outlet 3 of the crystallization can 1 is discharged. Backwash is performed. The above-mentioned cleaning route of the slurry outlet is shown by the hatched portion in FIG. After such washing, the washing pump 11 is stopped, the backwash valve 6 is opened, the washing valve 12 is closed, and copper sulfate is recovered again. The flow of each of the above steps is as shown in FIG.

[0009]

As described above, according to the present invention, when copper sulfate is recovered from the etching solution, the copper sulfate slurry is transferred from the crystallizer to the solid-liquid separator for solid-liquid separation. The copper sulphate crystals can be collected with maximum removal of the liquid content, and by heating the separated liquid and returning it to the etching process, it can be smoothly returned and easily reused as an etching liquid. Further, a part of the heated separation liquid is utilized to effectively wash the transfer route of the copper sulfate slurry in the crystallizer, whereby the copper sulfate can be recovered smoothly and efficiently.

[Brief description of drawings]

FIG. 1 is a system explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a crystal separation route of the present invention.

FIG. 3 is an explanatory diagram of a transfer pipe cleaning path of the present invention.

FIG. 4 is an explanatory diagram of a slurry outlet cleaning path of the present invention.

FIG. 5 is a flow chart of a process in an example of the present invention.

[Explanation of symbols]

 1 Crystallizer 2 Chiller 3 Outlet 4 Slurry extraction valve 5 Slurry extraction pump 6 Backwash valve 7 Transfer pipe 8 Centrifuge 9 Separation liquid outflow part 10 Intermediate tank 11 Wash pump 12 Wash valve 13 Wash pipe 14 Return pump 15 Etching tank 16 Overflow tank 17 Pump 18 Piping

Claims (2)

[Claims] 1. Crystals of copper sulfate pentahydrate are broken out by introducing an etching solution in which copper is dissolved into a crystallizer and cooling, and a copper sulfate pentahydrate slurry is taken out from the lower outlet of the crystallizer and solidified. In the copper sulfate recovery method in which crystals of copper sulfate pentahydrate are recovered by transferring to a liquid separator, and the separated liquid is heated in an intermediate tank and returned to the etching step, the heating solution in the intermediate tank is used. A copper sulfate pentahydrate slurry transfer passage between the crystallizer and the solid-liquid separator and a backwash of the copper sulfate pentahydrate slurry outlet of the crystallizer. Method. 2. Copper dissolved in an etching solution is replaced with copper sulfate 5
The copper sulfate 5 hydrate salt slurry outlet of a crystallizing can for cooling and precipitating as water salt crystals is connected to a solid-liquid separator by a transfer pipe, and the separated liquid outflow portion of the solid-liquid separator is connected to an etching tank for heating. The tank is connected to the tank, and the heating intermediate tank and the transfer pipe are connected via a washing pump so that the liquid in the heating intermediate tank is supplied into the transfer pipe between the crystallizer and the solid-liquid separator. A copper sulfate recovery device characterized in that