JP7673422B2 - Release agent slurry spraying device and spraying method using the same - Google Patents

Description

The present invention relates to a release agent slurry spraying device and a method for spraying release agent slurry using the same, and in particular to a release agent slurry spraying device that is sprayed into a mold for casting an electrolytic anode used in the electrolytic refining process of non-ferrous metals, and a method for spraying release agent slurry using the same.

In non-ferrous metal smelting processes, the grade of non-ferrous metals is gradually increased through dry processing, and then electrolytic refining is finally performed to produce high-purity non-ferrous metals. For example, in the copper smelting process, blister copper is oxidized and reduced in a previous refining furnace to produce molten blister copper with a purity of about 99.5%, which is then cast into roughly rectangular plates. The resulting anodes (hereafter referred to as "anodes") made of multiple copper plates and multiple separately prepared cathodes (hereafter referred to as "cathodes") are then alternately arranged and immersed one by one in the electrolyte in an electrolytic cell, and a voltage is applied to them to produce electrolytic copper.

The above-mentioned copper electrolytic refining is classified into the permanent cathode method (hereinafter referred to as the "PC method") and the conventional method (hereinafter referred to as the "seed plate method") depending on the type of cathode used. In the former PC method, a thin stainless steel plate is used as the cathode, and the electrolytic copper electrodeposited on the thin plate is peeled off from the thin plate in a subsequent peeling process and shipped as a product, and the thin plate is reused. On the other hand, in the latter seed plate method, a thin plate-shaped seed plate made of high purity copper is used as the cathode, and the electrolytic copper electrodeposited on the seed plate is shipped as a product together with the seed plate.

The power used for the electrodeposition is applied from a power source through busbar electrodes made of conductive plates provided on the upper surfaces of both opposing side walls of the electrolytic cell. Therefore, each of the anodes and cathodes has a pair of electrode contacts that serve as a support for supporting the anode and a terminal that contacts the busbar electrodes to pass electricity. For example, a roughly rectangular plate-shaped anode has a pair of electrode contacts, also called ears, that protrude horizontally from both upper corners. These electrode contacts are placed on the busbar electrodes and are not immersed in the electrolyte, so their thickness does not change before and after electrolytic refining. Therefore, they only need to have the strength to support the rectangular plate portion of the anode in a suspended state, and the pair of electrode contacts are made smaller and thinner than the rectangular plate portion that is immersed in the electrolyte.

In casting the above anode, in order to easily peel off the anode with the characteristic shape from the mold without deforming it, and to protect the mold from the molten metal poured into the mold after peeling, a release agent slurry is sprayed into the mold before pouring. It is preferable to spray this release agent slurry uniformly over the entire inner surface of the mold. However, since the parts where the pair of electrode abutment parts are cast are located at both corners of the mold, it was difficult to spray the release agent slurry uniformly over the entire surface, including the both corners, without protruding from the mold. In addition, since the both corners where the pair of electrode abutment parts are cast are narrow and shallow, a small amount of release agent is sufficient, and excessive spraying of the release agent could have a negative effect on the shape (wall thickness, etc.) of the pair of electrode abutment parts. Therefore, as shown in Patent Document 1, when spraying the release agent slurry onto the mold, it was common practice not to spray the release agent slurry directly onto the two corners of the mold where the pair of electrode contact parts are cast.

JP 2016-107308 A

In the spraying method of Patent Document 1, the release agent slurry can be poured to a certain extent from the center of the mold to both corners, but as described above, the pair of electrode abutment parts is thinner than the rectangular plate-shaped part, so the bottom surface of the anode is higher at both corners than at the center. Therefore, if the amount of release agent slurry sprayed at the center of the mold increases or decreases, the amount of release agent slurry flowing into both corners may be excessive or insufficient. In particular, if the release agent slurry is insufficient, the mold may be damaged, or the anode may become difficult to peel off, resulting in a defective shape of the anode. The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a spraying method and a spraying device that can spray an appropriate amount of release agent slurry to both corners where the pair of electrode abutment parts are cast in the anode mold.

In order to achieve the above object, the spraying device of the present invention is a spraying device that sprays a release agent slurry into a mold for casting an anode consisting of a rectangular plate-shaped portion and a pair of electrode abutment portions protruding from both corners of one end of the rectangular plate-shaped portion, and has a first spraying portion and a second spraying portion that branch and spray a release agent slurry having a certain slurry concentration onto a center portion where the rectangular plate-shaped portion and the pair of electrode abutment portions are cast, and onto both corner portions that are shallower than the center portion, and the second spraying portion is characterized in that its two injection nozzles are directed in a direction facing each other from diagonally above the both corner portions and in a direction from the both corner portions toward the central portion.

According to the present invention, an appropriate amount of release agent can be sprayed onto both corners of the anode mold where a pair of electrode abutment parts are cast.

1 is a schematic plan view of an electrolytic anode casting apparatus to which the method for spraying a release agent slurry of the present invention is suitably applied. FIG. 2 is a plan view of an electrolytic anode produced by the electrolytic anode casting apparatus of FIG. 1 . FIG. 2 is a perspective view of an anode mold provided on a turntable of the electrolytic anode casting apparatus of FIG. 1. FIG. 2 is a schematic flow diagram of a spraying device for a release agent slurry according to an embodiment of the present invention. FIG. 5 is a schematic diagram of a specific example of a mechanism for scanning a first emission portion of the release agent slurry spraying device of FIG. 4 . 4 is a chart showing the operation timing of the automatic valve of the spraying device according to the embodiment of the present invention and the operation mode performed thereby. FIG. 2 is a flow diagram showing a state in which all automatic valves are closed in the spraying device for a release agent slurry of the present invention. FIG. 2 is a flow diagram showing a state in which the release agent slurry is extracted into a supply piping system in the release agent slurry spraying device of the present invention. FIG. 2 is a flow diagram showing a state in which the release agent slurry is extracted into a branch piping system in the release agent slurry spraying device of the present invention. FIG. 2 is a flow diagram showing a state in which the release agent slurry is sprayed toward the center of an anode mold in the release agent slurry spraying device of the present invention. FIG. 2 is a flow diagram showing a state in which the release agent slurry is sprayed toward both corners of an anode mold and a gas is blown toward both corners in the release agent slurry spraying device of the present invention. FIG. 2 is a flow diagram showing a state in which gas is sprayed toward both corners of an anode mold in the device for spraying a release agent slurry of the present invention.

1. Anode Casting Apparatus First, an anode casting apparatus for electrolytic refining in a copper smelting plant, to which the release agent spraying apparatus and the release agent spraying method using the same of the present invention are suitably used, will be described. As shown in Fig. 1, an anode casting device 10 for continuously producing electrolytic anodes from molten blister copper is mainly composed of a pair of disk-shaped turntables 11 that rotate intermittently in the direction of the white arrow, a plurality of anode molds 12 provided on each turntable 11 at equal intervals in the circumferential direction, a trough section 13 for sequentially pouring molten blister copper refined in a previous refining furnace into the plurality of anode molds 12, a cooling device 14 for cooling the molten blister copper cast into the anode molds 12, a stripper 15 for stripping the electrolytic anodes solidified by cooling in the cooling device 14 from the anode molds 12, and a release agent spraying section 16 for spraying a slurry release agent into the anode molds 12 in advance to improve the releasability during stripping. Note that Fig. 1 shows an example in which 18 anode molds 12 are provided on each turntable 11, but the number of anode molds is not limited to this.

The electrolysis anode manufactured by the above-mentioned anode casting device 10 is immersed in the electrolyte in the electrolytic cell in a suspended state in the next process of electrolytic refining, and therefore has a characteristic shape as shown in the front view of FIG. 2. Specifically, the electrolysis anode A shown in FIG. 2 is composed of a substantially rectangular plate-shaped portion A1 of about 1000 mm length x 1000 mm width, and a pair of electrode abutment portions A2 that protrude from both upper corners of the rectangular plate-shaped portion A1 to the left and right of the paper surface. These pair of electrode abutment portions A2 are placed on the bus bar electrodes provided on the upper surfaces of both opposing side walls of the electrolytic cell. As a result, power is applied from a power source to the rectangular plate-shaped portion A1 of the electrolysis anode immersed in the electrolyte in the electrolytic cell through the bus bar electrode and the pair of electrode abutment portions A2 that abut against it.

2. Manufacturing method of electrolytic anodes The manufacturing method of electrolytic anodes using the anode casting device 10 having the above structure repeats a casting cycle consisting of a casting process in which molten blister copper is successively cast into a plurality of anode molds 12 placed on a turntable 11 that rotates intermittently in the direction of the white arrow, a cooling process in which the molten blister copper cast into the anode mold is cooled, a stripping process in which the electrolytic anode A solidified by cooling in the cooling process is stripped from the anode mold 12, and a release agent spraying process in which a release agent slurry is sprayed into the anode mold 12 immediately after the electrolytic anode A is stripped. Each of the casting process, cooling process, stripping process, and release agent spraying process will be described in detail below.

2.1 Casting process In the casting process, refined breeze copper, which has been increased to a purity of about 99.5% in a previous refining furnace, is sequentially cast through the trough section 13 into the anode molds 12 which are transported one after another below the trough section 13 by the intermittent rotation of the turntable 11. This trough section 13 is generally composed of a flow trough 13a which sends the refined breeze copper discharged from the refining furnace to the turntable 11, a storage trough 13b which distributes the refined breeze copper supplied from the flow trough 13a to the left and right, and a metering trough 13c which measures the refined breeze copper distributed by the storage trough 13b and pours it into the anode mold 12. This makes it possible to cast a constant amount of refined breeze copper into each anode mold 12, and to manufacture electrolysis anodes A with little variation.

2.2 Cooling step In the cooling step, the anode mold 12 filled with the refined blister copper cast in the previous casting step is sequentially introduced into a hood-shaped cooling device 14 by the rotation of the turntable 11, and the refined blister copper is cooled by spraying cooling water preferably from above and below through cooling water spray piping. This cooling causes the refined blister copper to solidify in the mold 12, and the electrolysis anode A is formed. In this cooling step, the anode mold 12 is also cooled to an appropriate temperature at the same time as the refined blister copper is cooled.

2.3 Stripping process The stripping process is a process in which the electrolysis anode A molded by cooling in the previous cooling process is stripped from the anode mold 12. As shown in Fig. 3, the anode mold 12 generally has a structure in which push-up pins P protrude from the bottom of the central portion 12a of the mold 12, and the molded electrolysis anode A is pushed up on the pair of electrode abutment portions by the push-up pins P, and this pushed-up portion is hooked or gripped by a stripping machine 15, thereby being removed from the anode mold 12. Note that before the electrolysis anode A is stripped by this stripping machine 15, an irregular anode stripping device may be provided to strip off defective anodes that have been determined to be defective by visual inspection or the like.

2.4 Release Agent Spraying Step The release agent spraying step is a step of spraying a release agent slurry prepared to a predetermined slurry concentration into the anode mold 12 after the electrolytic anode A has been peeled off in the previous step. The moisture contained in the sprayed release agent slurry evaporates due to the heat storage held by the anode mold 12, thereby forming a release layer on the inner surface of the mold 12. In the casting step of the next casting cycle, refined crude copper is cast on this release layer, so that the releasability of the electrolytic anode A from the anode mold 12 can be improved. The evaporation of the moisture contained in the release agent slurry sprayed in this release agent spraying step needs to be completed between immediately after the electrolytic anode is peeled off in the previous peeling step and the start of the casting step of the next casting cycle. In this way, in order to quickly evaporate the moisture contained in the release agent slurry, it is desirable to set the temperature of the anode mold 12 immediately after the electrolytic anode is peeled off to 100°C or higher.

3. Release agent slurry spraying device Next, a release agent slurry spraying device according to an embodiment of the present invention used in the release agent spraying step will be described with reference to Fig. 4. The spraying device shown in Fig. 4 is a device for spraying a release agent slurry toward the anode mold 12 immediately after the electrolytic anode A has been peeled off, and includes a storage tank 20 equipped with an agitator 20a that receives a release agent raw material such as clay powder together with industrial water, adjusts the slurry concentration (also called solids concentration) to preferably 20 to 200 g/L, more preferably 100 to 150 g/L, and stores the slurry, a slurry pump 21 consisting of, for example, a diaphragm pump that pressurizes the release agent extracted from the bottom of the storage tank 20, and a pump 22 for pumping the slurry. The system is composed of a supply piping system 22 which delivers the release agent pressurized by a pump 21 to a spraying position, a first discharge section 23 which is provided at the tip of the supply piping system 22 and which sprays a release agent slurry onto the central section 12 a of the anode mold 12, a branch piping system 24 which branches off from the supply piping system 22, a second discharge section 25 which is provided at the tip of the branch piping system 24 and which sprays the release agent slurry onto both corner sections 12 b of the anode mold 12, and a gas discharge section 26 which blows a gas such as compressed air onto both corners 12 b of the anode mold 12.

The release agent slurry may be prepared in a preparation tank other than the storage tank 20. In this case, the release agent slurry prepared in the preparation tank is transferred to the storage tank 20 using a slurry pump, gas pressure, head difference, etc. As shown in FIG. 4, it is preferable to circulate the release agent slurry extracted from the bottom of the storage tank 20 using an external circulation system in which the discharge side piping of the slurry pump 21 returns to the storage tank 20 in addition to stirring with the agitator 20a. This more reliably prevents the release agent, which is a solid content contained in the release agent slurry, from settling and separating due to gravity and accumulating at the bottom of the storage tank 20, so that the slurry concentration of the release agent slurry in the storage tank 20 can be kept uniform. The supply piping system 22 is branched off from the discharge side piping of the slurry pump 21 constituting this external circulation system, so that the release agent slurry having a constant slurry concentration can be sprayed from the first discharge section 23 and the second discharge section 25.

The first discharge section 23 preferably uses a two-fluid nozzle that sprays a mixture of the release agent slurry and the dispersion gas. This allows the release agent slurry, which has a higher solids concentration than a normal nozzle, to be sprayed almost uniformly over the center 12a of the anode mold 12, making it possible to mold a high-quality electrolysis anode A. This two-fluid nozzle consists of a roughly cylindrical mixing section and a roughly truncated cone-shaped spray section provided at the tip of the mixing section, where the release agent slurry and the dispersion gas introduced from different inlets are mixed. For this dispersion gas, for example, utility air supplied via a spray gas supply pipe 27 branched from an air header using a compressor or pressure cylinder as a compressed air supply source is preferably used.

The first release section 23 is preferably moved unilaterally along the bottom surface of the anode mold 12. This can be achieved, for example, by the mechanism shown in FIG. 5. Specifically, one end of a shaft section 33 is supported so as to be able to swing at the tip of a piston 32 that moves in and out of a cylinder 31 by the operation of a servo motor 30, and the first release section 23 is provided at the other end of the shaft section 33, while the central section of the longitudinal direction of the shaft section 33 is supported by a fixed shaft. This makes it possible to spray the release agent slurry over almost the entire surface of the central section 12a of the anode mold 12 by reciprocating the piston 32 with the servo motor 30.

As described above, the spraying device for the release agent slurry according to the embodiment of the present invention has a second spraying section 25 in addition to the first spraying section 23 as a spraying means for the release agent slurry. The second spraying section 25 may be a general spray nozzle, and its two nozzles are directed in a direction facing both corners 12b of the anode mold 12 from diagonally above, and in a direction from both corners 12b toward the center 12a. This makes it possible to reliably spray the release agent slurry to both corners 12b of the anode mold 12, and even if the release agent slurry is sprayed excessively to both corners 12b of the anode mold 12 by the second spraying section 25, the excess release agent slurry can be quickly discharged from both corners 12b to the center 12a.

Furthermore, the spraying device for the release agent slurry according to the embodiment of the present invention has a gas discharge section 26 that blows gas such as compressed air toward both corners 12b of the anode mold 12. As described above, when spraying the release agent slurry by the second discharge section 25 that targets both corners 12b of the anode mold 12, the flow of the release agent slurry tends to be in only one direction, and there is a risk that the release agent slurry may not reach both corners 12b of the anode mold 12 sufficiently. However, by spraying gas from the two nozzles of the gas discharge section 26 toward both corners 12b of the anode mold during and after the spraying of the release agent slurry by the second discharge section 25, the small amount of release agent slurry sprayed on both corners 12b can be spread over almost the entire inner surface of both corners 12b by the sprayed gas.

In addition, when an excess of release agent slurry is sprayed on both corners 12b of the anode mold 12, some of the release agent adheres to the surface of both corners 12b, while others accumulate on the release agent. However, it is possible to blow the release agent that accumulates on the release agent out of both corners 12b. This makes it possible to prevent the shape (thickness, etc.) of the electrode contact portion A2 of the electrolytic anode A from varying. By timing the spraying of the gas during or immediately after spraying the release agent slurry, moisture can also be blown out of both corners 12b. Therefore, even if the release agent slurry is sprayed excessively on both corners 12b of the anode mold 12, the moisture in the release agent slurry can be easily evaporated before casting.

A general gas nozzle can be used for the gas discharge section 26. This gas nozzle is installed with its gas discharge port facing both corners 12b from above and tilted so that it discharges from both corners 12b toward the center section 12a, so that the release agent slurry blown away by the gas is less likely to scatter outside the anode mold 12 and can be effectively used in the center section 12a. For example, general purpose air supplied via a gas discharge pipe 29 branching off from the air header is used for the gas discharge section 26.

As described above, in each of the multiple anode molds 12 provided on the turntable constituting the anode casting device 10, a casting cycle consisting of a casting process, a cooling process, a stripping process, and a release agent spraying process is repeated by the intermittent rotation of the turntable 11. It is necessary to spray the release agent slurry intermittently in sequence to the multiple anode molds 12 in accordance with this casting cycle. For this reason, the supply piping system 22 and the branch piping system 24 of the spraying device of the embodiment of the present invention are provided with a spray valve 22a and a corner spray valve 24a, respectively, which are automatically opened and closed. This allows the release agent slurry to be sprayed in accordance with the timing of the intermittent rotation of the turntable 11.

The amount of release agent slurry extracted from the external circulation system can be adjusted by opening and closing the spray valve 22a. By appropriately changing the length of time that the spray valve 22a is open, the amount of release agent slurry sprayed from the first release section 23 to the center section 12a of the anode mold 12 can be adjusted. Similarly, by appropriately changing the length of time that the corner spray valve 24a is open, the amount of release agent slurry sprayed from the second release section 25 to both corner sections 12b of the anode mold 12 can be adjusted. In order to stabilize the flow rate of the release agent slurry extracted from the storage tank 20, including the external circulation system, a circulation shutoff valve may be provided downstream of the branch point of the supply piping system 22 in the external circulation system.

Furthermore, in the spraying device for release agent slurry according to the embodiment of the present invention, the downstream side of the spray valve 22a in the supply piping system 22 has a capacity capable of holding an amount of release agent slurry corresponding to the opening time of the spray valve 22a, and similarly, the downstream side of the corner spray valve 24a in the branch piping system 24 has a capacity capable of holding an amount of release agent slurry corresponding to the opening time of the corner spray valve 24a. Then, the release agent slurry is extracted from the external circulation system to the supply piping system 22 and the branch piping system 24 and temporarily held in both piping systems, and then a purge gas is introduced into the supply piping system 22 and the branch piping system 24, so that the extracted and held release agent slurry is sprayed onto the anode mold 12. This makes it possible to suppress variation in the amount of release agent slurry sprayed onto each anode mold 12.

If the release agent slurry is to be sprayed from the two-fluid nozzle of the first discharge section 23, for example, by using the discharge pressure of the slurry pump 21, it is necessary to set the discharge pressure of the slurry pump 21 higher so that the spray valve 22a is left open and the inlet pressure of the two-fluid nozzle is maintained higher than the lower limit required for stable spraying. In this case, even if the spray valve 22a is switched from open to closed, the spraying of the release agent slurry from the two-fluid nozzle does not immediately stop. However, the pressure and kinetic energy of the release agent slurry flowing in the supply piping system 22 gradually decrease due to friction with the inner wall surface of the supply piping system 22 after the spray valve 22a is switched from open to closed, so that the pressure eventually decreases and the flow rate slows down, and the release agent slurry is no longer sprayed from the two-fluid nozzle. As a result, some of the release agent slurry remains in the supply piping system 22.

As described above, the amount of release agent slurry remaining in the supply piping system 22 after the spray valve 22a is closed is greatly influenced by the degree to which the kinetic energy and pressure of the release agent slurry flowing through the supply piping system 22 immediately after the spray valve 22a is switched from open to closed, due to pressure loss and the like in the supply piping system 22. Therefore, the amount of release agent slurry sprayed may vary for each anode mold 12, which may cause variation in the quality of the electrolysis anode A.

In contrast, in the spraying device for the release agent slurry according to the embodiment of the present invention, a purge gas supply pipe 28 for introducing a purge gas is connected to the supply pipe system 22 immediately adjacent to the secondary side (downstream side) of the spray valve 22a. As a result, the purge gas is introduced into the supply pipe system 22 and the branch pipe system 24 by switching the purge gas valve 28a, which opens and closes automatically, from closed to open in accordance with the timing when the spray valve 22a switches from open to closed, for example. Therefore, the entire amount of the release agent slurry that has been extracted and held in the supply pipe system 22 and the branch pipe system 24 before the purge gas valve 28a switches from closed to open can be sprayed onto the anode mold 12.

In this way, by introducing a purge gas into the supply piping system 22, the amount of release agent slurry introduced from the external circulation system into the supply piping system 22 and the branch piping system 24 in one casting cycle of each anode mold 12 can be made substantially equal to the amount of release agent slurry sprayed from the supply piping system 22 and the branch piping system 24 onto the anode mold 12, thereby suppressing variation in the amount of release agent slurry sprayed for each anode mold 12. In addition, since the time during which the spray valve 22a is open can be made directly proportional to the amount of release agent slurry sprayed onto each anode mold 12, the amount of release agent slurry sprayed (sprayed) can be precisely adjusted by simply increasing or decreasing the time during which the spray valve 22a is open. The gases for purging, gas release, and the two-fluid nozzle are not particularly limited as long as they do not substantially cause a chemical reaction with the material of the liquid-contacting parts such as the supply piping system 22 and the mold release agent slurry. For example, compressed air or compressed nitrogen can be used, and compressed air is preferred from the viewpoint of low cost.

In one casting cycle consisting of the above-mentioned pouring (pouring), cooling, stripping, and spraying of the release agent in each anode mold 12, the amount and pressure of the purge gas introduced into the supply piping system 22 may be such that almost all of the release agent slurry in the supply piping system 22 can be pushed out from the first discharge section 23 and the second discharge section 25. The pressure of this purge gas is preferably higher than the pressure at which the release agent slurry is extracted from the external circulation system, so that all of the release agent slurry can be sprayed at the timing of the intermittent rotation of the turntable 11. In addition, the timing at which the purge gas is introduced into the supply piping system 22 to purge the release agent slurry in the supply piping system 22 is preferably such that the extraction of the release agent slurry from the external circulation system to the supply piping system 22 is not hindered or a backflow occurs, and it is preferable to open the purge gas valve 28a when the spray valve 22a is closed.

4. Method for spraying release agent slurry Next, the method for spraying release agent slurry according to the embodiment of the present invention will be described in detail with reference to the chart in Fig. 6, which shows the open/close states and operation modes of the automatic valves of the spraying device for release agent slurry described above, and the flow sheets in Figs. 7 to 12. In Figs. 7 to 12, the white valves indicate the closed state, and the black valves indicate the open state. For simplicity, the second discharge part 25 and the gas discharge part 26 each show only one of the two nozzles.

As shown in Fig. 7, in the spraying device, all the automatic valves are in a closed state. First, in step No. 1, the spray valve 22a is opened from closed to open, and the release agent slurry is extracted from the external circulation system to the supply piping system 22 as shown in Fig. 8. Next, in step No. 2, the spray valve 22a is left open, and the corner spray valve 24a is opened from closed to open, and the release agent slurry is extracted to the branch piping system 24 as shown in Fig. 9. Next, in step No. 3, the corner spray valve 24a is opened from open to closed while the spray valve 22a is left open, and then the spray gas valve 27a is opened from closed to open to introduce compressed gas into the first discharge part 23. Next, in step No. 4, the spray valve 22a is opened from open to closed, and at the same time the purge gas valve 28a is opened from closed to open, and the release agent slurry is sprayed from the first discharge part 23 as shown in Fig. 10. Next, in step No. 5, the servo motor 30 is operated to scan the first emission section 23 along the bottom surface of the anode mold 12.

Next, in step No. 6, almost all of the release agent slurry extracted into the supply piping system 22 is sprayed from the first discharge section 23, and only purge air is discharged from the first discharge section 23, so the operation of the servo motor 30 is stopped to stop the scanning of the first discharge section 23. In this way, by leaving the spray gas valve 27a and the purge gas valve 28a open for a while even after almost all of the release agent slurry in the supply piping system 22 has been sprayed from the first discharge section 23, the inside of the supply piping system 22 and the two-fluid nozzle can be cleaned.

Next, in step No. 7, as shown in FIG. 11, the corner spray valve 24a is opened while the purge gas valve 28a is left open, and the release agent slurry is sprayed from diagonally above by the second release section 25 in the direction from both corners 12b of the anode mold 12 toward the center 12a of the anode mold 12. Furthermore, the gas release valve 29a is opened, and compressed gas is sprayed from the gas release section 26 toward both corners 12b. This spreads the release agent slurry, so that the release agent slurry can be sprayed over the entire surfaces of both corners 12b.

Next, in step No. 8, the corner spray valve 24a is switched from open to closed, as shown in FIG. 12, to stop spraying the release agent slurry onto both corners 12b of the anode mold 12, and only the gas spray from the pair of gas discharge ports 26 is maintained onto both corners 12b. This allows excess release agent and moisture to be blown away, and an appropriate amount of release agent slurry can be applied to the inner surfaces of both corners 12b of the anode mold 12. Note that, even in steps No. 7 and No. 8, it is preferable to continue cleaning with gas by leaving the spray gas valve 27a and purge gas valve 28a open.

Finally, in step No. 9, the gas release valve 29a is changed from open to closed, and the spray gas valve 27a and the purge gas valve 28a are also changed from open to closed. As a result, all automatic valves are closed as shown in FIG. 7, and the spraying of the release agent slurry to one anode mold 12 is completed. The opening and closing of the spray valve 22a, both corner spray valves 24a, spray gas valve 27a, purge gas valve 28a, and gas release valve 29a is generally controlled by a control means such as a CPU (central processing unit) or a PLC (programmable logic controller).

As described above, the spraying device for release agent slurry according to the embodiment of the present invention and the spraying method using the same make it possible to spray an appropriate amount of release agent slurry to both corners 12b of the anode mold 12 where a pair of electrode abutment parts are cast. In addition, by separating the timing of drawing out the release agent slurry to the supply piping system 22 and the spraying of the release agent slurry temporarily held in the supply piping system 22 to the anode mold 12, it becomes possible to stably spray the release agent slurry to both the center 12a and both corners 12b without any particular adverse effect on the spraying of the release agent slurry to the center 12a, even though the line for spraying the release agent slurry to the center 12a of the anode mold 12 and the line for spraying the release agent slurry to the corners 12b are partially shared. Furthermore, since the release agent slurry remaining in the system after the spraying can be removed, the system is less likely to become clogged with the release agent.

In addition, since the release agent slurry is dispersed in the central portion 12a of the anode mold 12 by the dispersion gas, the release agent slurry can be widely dispersed on the inner surface of the central portion 12a of the anode mold 12. Since the dispersion gas plays a role in spreading the release agent slurry in place of water or in cooperation with water, the amount of water contained in the release agent slurry can be reduced as necessary. This allows the water contained in the release agent slurry to evaporate quickly, so that a smooth electrolytic anode with almost no blistering on the surface can be manufactured without causing the problem of burning in the mold. As a result, in the electrolytic refining process in the subsequent process, the occurrence rate of short circuits between the anode and the cathode due to unevenness such as blistering on the surface of the electrolytic anode can be reduced, and the productivity of the copper refining process can be significantly improved.

Furthermore, since the system can be cleaned with a purge gas after the release agent slurry has been sprayed, a variety of release agents can be used with various solids concentrations. For example, it is possible to use a release agent that has the property of easily adhering to the inner wall of the pipe over time, or a release agent slurry that has a high solids concentration and is likely to clog the inside of the pipe. Specifically, it is possible to significantly expand the range of solids concentration of the release agent slurry from the conventional range of about 30 to 60 g/L to about 20 to 160 g/L. Also, it is possible to significantly expand the range of spray amount of the release agent slurry from the conventional range of about 1500 to 2200 mL to about 500 to 3600 mL.

(Example)
A spraying device for the release agent slurry having an automatic valve as shown in Fig. 4 was opened and closed in accordance with the sequence shown in the chart of Fig. 6, to spray the release agent slurry to each anode mold of the anode casting facility as shown in Fig. 1. Specifically, in steps 1 to 3 shown in the chart of Fig. 6, the spray valve 22a was opened for a total of 3 seconds to extract and hold the release agent slurry in the supply piping system 22. During that time, the corner spray valve 24a was opened in step No. 2 to hold the release agent slurry in the branch piping system 24.

In the above steps 1 to 3, the release agent slurry was not sprayed from the first release section 23 and the second release section 25. In addition, by increasing or decreasing the open time of the spray valve 22a from the above 3 seconds, it was possible to adjust the spray time of the release agent slurry onto the anode mold in the subsequent step. From this, it was found that the amount of extraction to the supply piping system 22 can be adjusted by the time for which the spray valve 22a is open.

In steps 4 to 8, the release agent slurry extracted to the supply piping system 22 was pushed out by the pressure of compressed air by opening the purge gas valve 28a of the purge gas supply piping 28, and was stably sprayed from the two-fluid nozzle of the first discharge section 23. After the spraying of the release agent slurry from the two-fluid nozzle was almost completed, the corner spray valve 24a was opened again in step 7, and the release agent slurry held in the branch piping system 24 was pushed out by the pressure of compressed air introduced from the purge gas supply piping 28, and was sprayed from the second discharge section 25 to both corners 12b of the anode mold 12. In steps 7 and 8, the gas release valve 29a was opened, and compressed air was blown from the gas release section 26 to both corners 12b of the anode mold 12 during and after the spraying of the release agent slurry to the corners 12b.

Electrolytic anodes A were cast for half a year using the above-mentioned method for spraying the release agent slurry. As a result, the incidence of electrolytic anodes A with shape defects at the contact points of the pair of electrodes was extremely low at 0.001%. In addition, the anode mold required replacement only once a year due to damage to the corners where the contact points of the pair of electrodes were cast. Furthermore, visual inspection after operation by opening the mold for inspection revealed no particular residue or adhesion of release agent inside the piping system of the spraying device.

Comparative Example
An electrolysis anode A was cast in the same manner as in the above-mentioned Example, except that the release agent slurry was not directly sprayed onto both corners 12b of the anode mold 12 and gas was not released into the both corners 12b. As a result, the incidence rate of electrolysis anodes A having shape defects at the pair of electrode abutment parts was 0.01%, significantly higher than in the Examples. In addition, the frequency of replacement of the anode mold, which was required due to damage to the both corners where the pair of electrode abutment parts were cast, was 10 times per year, significantly higher than in the Examples.

(Reference example)
A release agent slurry spraying device that does not have the function of supplying compressed air for air purging to the supply piping system of the release agent slurry was used to cast the electrolytic anode A. Visual inspection by open inspection after operation revealed that the release agent remained inside the supply piping system. Casting was continued without cleaning by air purging, and as a result, the piping system became clogged after 3,000 casting cycles.

REFERENCE SIGNS LIST 10 Anode casting equipment 11 Turntable 12 Anode mold 12a Central portion 12b Both corner portions 13 Gutter portion 14 Cooling device 15 Stripping machine 16 Release agent spraying portion 20 Storage tank 20a Agitator 21 Slurry pump 22 Supply piping system 22a Spray valve 23 First discharge portion 24 Branch piping system 24a Corner spray valve 25 Second discharge portion 26 Gas discharge portion 27 Spray gas supply piping 27a Spray gas valve 28 Purge gas supply piping 28a Purge gas valve 29 Gas discharge piping 29a Gas discharge valve 30 Servo motor 31 Cylinder 32 Piston 33 Shaft portion A Electrolytic anode P Push-up pin

Claims (6)

A spraying device for spraying a release agent slurry into a mold for casting an anode comprising a rectangular plate-shaped portion and a pair of electrode abutment portions protruding from both corners of one end of the rectangular plate-shaped portion, the spraying device having a first release portion and a second release portion for branching and spraying a release agent slurry having a constant slurry concentration to a center portion where the rectangular plate-shaped portion and the pair of electrode abutment portions are cast and to both corner portions shallower than the center portion, the second release portion having two jet nozzles that are directed in a direction facing each other from obliquely above the both corner portions and in a direction from the both corner portions toward the central portion. The spraying device according to claim 1, characterized in that a gas supply pipe is connected to a piping system that supplies the release agent slurry to the second discharge section. The spraying device according to claim 1 or 2, further comprising a gas discharge section for blowing gas toward both corners so that the release agent slurry spreads thinly over the entire surfaces of both corners. A method for spraying a release agent slurry using the spraying device according to claim 3, characterized in that gas is sprayed from the gas release section both during and after spraying of the release agent slurry to both corners. A method for spraying a release agent slurry using the spraying device according to claim 2, characterized in that the release agent slurry is supplied to the second discharge section through a branch piping system branched from a main piping system that supplies the release agent slurry to the first discharge section, and the corner spray valve provided in the branch piping system opens for a certain period of time while the release agent slurry is being extracted to the main piping system, and then opens again when a purge gas is introduced into the main piping system. 6. The method for spraying a release agent according to claim 5, characterized in that the branch piping system has a capacity capable of holding an amount of release agent slurry corresponding to an opening time of the corner spray valve on the downstream side of the corner spray valve, and the purge gas has a pressure equal to or higher than a pressure required for spraying the held release agent slurry from the second release part.

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