Method for dispersing release agent slurry and anode casting method using the same

Abstract

To provide a method for scattering release agent slurry capable of optionally changing the scattering amount of release agent slurry.SOLUTION: A method for scattering release agent slurry comprises: a step in which, by an outside circulation system that rises the pressure of release agent slurry taken out from the bottom part of a storage tank 10 of the release agent slurry and returns the same to the storage tank 10, the release agent slurry is circulated; and a step in which the release slurry taken out from the outside circulation system to a branched feed piping 14 is scattered from a nozzle 15 as scattering means provided at the tip part of the feed piping 14 over a cast C. The scattering amount of the release agent slurry is adjusted in accordance with the time during which an automatic valve 14a provided at the feed piping 14 is opened, and further, after the automatic valve 14a is closed, a gas for purge is introduced into the downstream side thereof to scatter the release agent slurry in the feed piping 14 from the scattering means.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for spraying a release agent slurry onto an anode mold used in casting an anode, which is handled as an intermediate product in a non-ferrous metal smelting process such as copper smelting, and a method for casting an anode using the same. [Background technology]

[0002] In the non-ferrous metal refining process, the grade of the molten non-ferrous metals is gradually increased by dry processing, and then the molten non-ferrous metals are finally subjected to electrolytic refining to produce high-purity non-ferrous metals. For example, in the electrolytic refining of copper, the molten refined blister copper with a purity of about 99.5% produced by oxidizing and reducing the blister copper in the previous refining furnace is cast into a roughly rectangular plate, and the resulting anode (hereinafter referred to as "anode") made of multiple copper plates and multiple separately prepared cathodes (hereinafter referred to as "cathode") are alternately arranged one by one and immersed in the electrolyte in an electrolytic cell, and a voltage is applied to them to produce electrolytic copper.

[0003] The above-mentioned copper electrolytic refining can be classified into a permanent cathode method (hereinafter referred to as the "PC method") and a conventional method (hereinafter referred to as the "seed plate method") depending on the type of cathode used. In the former PC method, a stainless steel thin 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.

[0004] In the above-mentioned copper electrolytic refining, in order to increase productivity, the anode and the cathode are arranged as close to each other as possible in the electrolytic cell, so if the surface of the anode body is uneven, the anode and the cathode may come into contact with each other and cause a short circuit. If a short circuit occurs in the electrolytic cell, the electrolytic efficiency decreases, so in the casting of the above-mentioned refined blister copper, it is desirable to mold a smooth anode without unevenness on its surface.

[0005] One of the reasons for the unevenness of the anode surface is thought to be the anode sticking to the mold during casting. As a countermeasure to this, Patent Document 1 discloses a technique for forming a layer of a mold release agent made of clay powder and water glass on the inner surface of the anode mold before pouring the molten metal. It is described that this prevents the anode from sticking during casting and allows the molding of a smooth anode with no unevenness on the surface. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 2896764 specification Summary of the Invention [Problem to be solved by the invention]

[0007] As shown in the above Patent Document 1, by forming a layer of a release agent (hereinafter referred to as "release layer") on the inner surface of the anode mold, it is possible to prevent problems such as seizure during casting and unevenness of the anode surface caused by it. However, since the release layer is formed by spraying a release agent slurry prepared by adding water to a release agent onto the anode mold, water may evaporate during casting, resulting in the formation of a blister-like convex portion (hereinafter referred to as "blister") formed of a thin film with a hollow interior on the surface of the anode. If such a blister occurs on the surface of the anode, the current is preferentially consumed in the blister during electrolysis, and as a result, some of the blister may break or peel off, which may cause the above-mentioned short circuit problem. In order to suppress the occurrence of this blister, it is desirable to spray an optimal amount of release agent slurry onto each anode mold.

[0008] The optimum amount of the release agent slurry to be sprayed can be determined based on criteria such as the releasability of the anode from the mold. Examples of the criteria include the wear of the inner surface of the mold and the mold temperature at the time of spraying the release agent slurry, and the optimum amount of spraying is adjusted based on these criteria. However, it is generally difficult to flexibly change the amount of spraying once it has been designed.

[0009] Therefore, the amount of release agent slurry sprayed onto the mold was prone to be excessive or insufficient. For example, if an excessive amount of release agent slurry is sprayed onto the mold, it takes too long for the moisture to evaporate from the inner surface of the mold, leaving some of the release agent slurry remaining. This may cause the molten blister copper poured into the mold to boil during casting, resulting in voids or the above-mentioned swelling of the anode. Conversely, if the amount of release agent slurry sprayed onto the mold is insufficient, the anode may not be peeled off well from the mold, and the anode may be deformed if it is forcibly peeled off. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for spraying a release agent slurry that allows the amount of release agent slurry sprayed to be freely changed. [Means for solving the problem]

[0010] The release agent slurry to be sprayed on the mold is usually prepared by adding water to a release agent made of clay powder in a preparation tank equipped with a stirrer so that the solid content concentration (i.e. the mass of the release agent per unit volume of the release agent slurry) is about 30 to 60 g / L. In order to spray the release agent slurry having such a relatively high solid content concentration on the mold as uniformly as possible, it is preferable to pressurize the release agent slurry extracted from the bottom of the preparation tank, where the suspension state is maintained by stirring, to a predetermined pressure by a pressure increasing means such as a slurry pump, and to spray it over a wide area through a spraying means such as a nozzle. In this case, when the pressure increase by the pressure increasing means is stopped, a part of the release agent slurry flowing in the supply pipe from the pressure increasing means to the spraying means is sprayed from the spraying means as it is due to inertia, but the remainder remains in the supply pipe due to a pressure decrease due to friction with the inner wall of the supply pipe or adhesion to the inner wall surface.

[0011] The present inventors have focused on the fact that the amount of the release agent slurry sprayed from the spraying means after the above-mentioned pressure increasing means is not constant but varies. The factors (disturbances) that cause the variation in the amount of the release agent slurry sprayed after the pressure increasing means is stopped include fluctuations in the liquid level of the release agent slurry in the preparation tank, fluctuations in the pressure of the utility air used for operating various devices in the factory, and a decrease in the pressure of the release agent slurry due to adhesion of the release agent in the supply pipe. Therefore, after repeated studies on methods to suppress the adverse effects of these disturbances, it was found that the amount of the release agent slurry sprayed on each anode mold can be stabilized by devising a method for spraying the release agent slurry, and this led to the completion of the present invention.

[0012] That is, the method for spraying a release agent slurry of the present invention comprises a step of circulating the release agent slurry by an external circulation system which pressurizes the release agent slurry extracted from the bottom of a storage tank of the release agent slurry and returns the pressurized release agent slurry to the storage tank, and a step of spraying the release agent slurry extracted into a supply pipe branching from the external circulation system onto a mold from a spraying means provided at the tip of the supply pipe, in which the amount of spraying of the release agent slurry is adjusted depending on the time during which an automatic valve provided in the supply pipe is in an open state, and after the automatic valve is closed, a purge gas is introduced downstream of the automatic valve to spray the release agent slurry in the supply pipe from the spraying means. The release agent slurry is sprayed onto the mold by introducing the purge gas into the supply pipe. It is characterized by the following. Effect of the Invention

[0013] According to the present invention, the amount of the release agent slurry to be sprayed can be changed as desired. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic flow diagram of a release agent slurry supply facility to which a release agent slurry spraying method according to an embodiment of the present invention is suitably applied. [Diagram 2] FIG. 2 is a schematic diagram of a specific example of a mechanism for scanning the nozzle for spraying the release agent slurry in FIG. 1. [Diagram 3] 1 is a timing chart showing the opening and closing operations of various valves of a release agent slurry supplying facility performed in accordance with a method for spraying a release agent slurry according to an embodiment of the present invention, and the corresponding operation modes. [Figure 4] FIG. 11 is a timing chart showing the opening and closing operations of various valves of a release agent slurry supplying facility performed in accordance with a method for spraying a release agent slurry according to another embodiment of the present invention, and the corresponding operation modes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The method for spraying a release agent slurry according to the embodiment of the present invention will be described below. First, a release agent slurry supplying facility to which the method for spraying a release agent slurry according to the embodiment of the present invention is suitably applied will be described with reference to FIG. The release agent slurry supplying equipment shown in Fig. 1 is composed of a storage tank 10 equipped with an agitator 10a that receives a release agent such as clay powder together with industrial water, adjusts the solid content concentration to preferably 20 to 120 g / L, more preferably 40 to 60 g / L, and stores the same, a slurry pump 12, preferably an air-driven diaphragm pump, that pressurizes the release agent slurry extracted from an extraction pipe 11 at the bottom of the storage tank 10, a return pipe 13 that returns the release agent slurry pressurized by the slurry pump 12 to the storage tank 10, a supply pipe 14 that branches off from a branch point P of the return pipe 13 in order to extract the release agent slurry pressurized by the slurry pump 12, and a nozzle 15 that is provided at the tip of the supply pipe 14 in order to spray the release agent slurry on the inner surface of a mold C on a turntable of an anode casting device (not shown). The preparation of the release agent slurry may be carried out in a preparation tank other than the storage tank 10. In this case, the release agent slurry prepared in the preparation tank is transferred to the storage tank 10 by using a slurry pump, gas pressure transfer, head difference, or the like.

[0016] The nozzle 15 is preferably a two-fluid nozzle that injects the release agent slurry and the dispersion gas in a mixed state. This allows the release agent slurry, which has a higher solid content concentration than a normal nozzle, to be almost uniformly sprayed onto the inner surface of the mold, making it possible to mold a high-quality anode with little bulging. This two-fluid nozzle is composed of a mixing section having a substantially cylindrical shape and an injection section having a substantially truncated cone shape provided at the tip of the mixing section, where the release agent slurry introduced from the side inlet and the dispersion gas introduced from the end inlet are mixed. For example, general purpose air is used as the dispersion gas, which is supplied via an injection gas supply pipe 17 branched off from the air header 16.

[0017] It is preferable that the nozzle 15 is unilaterally scanned along the bottom surface of the recess of the mold C. This can be realized, for example, by a mechanism shown in FIG. 2. Specifically, one end of a shaft portion 23 is supported so as to be able to swing at the tip of a piston 22 that is extended and retracted from a cylinder 21 by the operation of a servo motor 20, and the nozzle 15 is provided at the other end of the shaft portion 23, while the central portion in the longitudinal direction of the shaft portion 23 is supported by a fixed shaft. In this way, by reciprocating the piston 22 by the servo motor 20, it becomes possible to spray the release agent slurry over almost the entire inner surface of the mold C.

[0018] As described above, in the release agent slurry supply equipment, the release agent slurry extracted from the bottom of the storage tank 10 is circulated by using the external circulation system consisting of the extraction pipe 11, the slurry pump 12, and the return pipe 13. In cooperation with the agitator 10a, the release agent contained in the release agent slurry can be prevented from settling and separating due to gravity and accumulating on the bottom of the storage tank 10, and the solid content concentration of the release agent slurry in the storage tank 10 can be kept uniform. This makes it possible to keep the solid content concentration of the release agent slurry sprayed onto the anode mold uniform through the supply pipe 14 branched off from the branch point P of this external circulation system and the nozzle 15 provided at the tip of the supply pipe 14.

[0019] Meanwhile, a plurality of molds C are disposed at equal intervals in the circumferential direction on a disk-shaped turntable constituting the above-mentioned anode casting device, and with the intermittent rotation of the turntable, a cycle is repeated in each of the plurality of molds C, which includes pouring molten blister copper, cooling and solidifying the poured molten blister copper, peeling off the anode formed by the solidification, and spraying a release agent slurry onto the mold C after the peeling off.

[0020] Therefore, the release agent slurry needs to be sprayed intermittently to the plurality of molds C in sequence, and for this purpose, the supply pipe 14 is provided with a spray valve 14a that opens and closes automatically. This allows the release agent slurry to be sprayed in accordance with the timing of the intermittent rotation of the turntable. In addition, the amount of the release agent slurry extracted from the external circulation system can be adjusted by opening and closing the spray valve 14a, so that the amount of the release agent slurry introduced into the nozzle 15 through the supply pipe 14 can be adjusted according to the length of time that the spray valve 14a is open. In order to stabilize the extraction of the release agent slurry from the external circulation system, as shown in FIG. 1, a circulation cutoff valve 13a is provided downstream of the branch point P in the return pipe 13 that constitutes the external circulation system.

[0021] Incidentally, in order to stably inject the release agent slurry from the nozzle 15, the inlet pressure of the nozzle 15 may be maintained higher than a predetermined lower limit by setting the discharge pressure of the slurry pump 12 to an appropriate pressure. In this case, even if the spray valve 14a is switched from open to closed, the injection of the release agent slurry from the nozzle 15 does not immediately stop. However, after the spray valve 14a is switched from open to closed, the pressure and kinetic energy of the release agent slurry flowing in the supply pipe 14 gradually decrease due to friction with the inner wall surface of the supply pipe 14, and the pressure eventually decreases and the flow speed decelerates, so that the release agent slurry is no longer injected from the nozzle 15. As a result, a part of the release agent slurry remains in the supply pipe 14. In other words, the amount of the release agent slurry injected from the nozzle 15 after the spray valve 14a is closed is smaller than the amount of the release agent slurry present in the supply pipe 14 immediately after the spray valve 14a is closed in one cycle.

[0022] If a part of the release agent slurry remaining in the supply pipe 14 after the closure of the spray valve 14a is not discharged, it will be carried over to the spraying to the adjacent subsequent mold C on the turntable. That is, the amount of the release agent slurry sprayed to the subsequent mold C is the amount obtained by subtracting the amount of the release agent slurry remaining in the supply pipe 14 after the closure of the spray valve 14a in the same manner as above from the amount of the release agent slurry supplied from the external circulation system to the supply pipe 14 by opening the spray valve 14a at the time of spraying to the subsequent mold C, plus the amount of the release agent slurry carried over from the spraying to the preceding mold C.

[0023] The amount of the release agent slurry remaining in the supply pipe 14 after the closure of the spray valve 14a is largely dependent on the degree to which the kinetic energy and pressure of the release agent slurry flowing in the supply pipe 14 immediately after the spray valve 14a is switched from open to closed, is reduced due to the pressure loss in the supply pipe 14, as described above. Therefore, the amount of the release agent slurry sprayed onto the multiple molds C varies for each mold C. In order to suppress this variation, the method for spraying the release agent slurry according to the embodiment of the present invention introduces a purge gas into the supply pipe 14, so that the release agent slurry extracted from the external circulation system into the supply pipe 14 is sprayed onto the molds C through the nozzle 15.

[0024] Specifically, a purge gas supply pipe 18 for introducing a purge gas is connected to the supply pipe 14 in the immediate vicinity of the secondary side (downstream side) of the spray valve 14a. As a result, for example, in accordance with the timing when the spray valve 14a changes from open to closed, the purge gas valve 18a provided in the purge gas supply pipe 18, which opens and closes automatically, is opened from closed to open to introduce the purge gas into the supply pipe 14. As a result, most of the release agent slurry remaining in the supply pipe 14 after the spray valve 14a is closed can be sprayed from the nozzle 15 to the mold C.

[0025] As described above, by introducing the purge gas into the supply pipe 14, the amount of the release agent slurry introduced from the external circulation system into the supply pipe 14 and the amount of the release agent slurry sprayed from the supply pipe 14 through the nozzle 15 onto the molds C in one cycle of each mold C can be made substantially equal, so that it is possible to suppress the variation in the amount of the release agent slurry sprayed onto each mold C. In addition, since the open time of the spray valve 14a and the amount of the release agent slurry sprayed onto each mold C can be made directly proportional to each other, the amount of the release agent slurry sprayed (sprayed) can be precisely adjusted by simply increasing or decreasing the open time of the spray valve 14a.

[0026] In one cycle of pouring, cooling and solidifying, stripping, and spraying for each mold C, the amount and pressure of the purge gas to be introduced into the supply pipe 14 after the spraying may be such that almost all of the release agent slurry in the supply pipe 14 can be pushed out from the nozzle 15. The timing of introducing the purge gas into the supply pipe 14 in order to purge the release agent slurry in the supply pipe 14 is preferably a timing at which the withdrawal of the release agent slurry from the external circulation system to the supply pipe 14 is not hindered or a backflow does not occur, and it is desirable to open the purge gas valve 18a when the spray valve 14a is in a closed state.

[0027] Specifically, as shown in the timing chart of Fig. 3, which shows a series of steps performed when spraying the release agent slurry in each mold C, the spray valve 14a is first opened from closed to extract the release agent slurry from the external circulation system to the supply pipe 14 (steps No. 1 to 3). At this time, in order to perform more stable extraction, it is preferable to temporarily switch the external circulation valve 13a of the external circulation system from open to closed (step No. 2). Moreover, when a certain amount of the release agent slurry has been extracted, the injection gas valve 17a is switched from closed to open (step No. 3).

[0028] Next, the spray valve 14a is changed from open to closed, and at the same time, the purge gas valve 18a is changed from closed to open. This causes the release agent slurry to be sprayed from the nozzle 15 (steps No. 4 to 5). It is preferable to operate the cylinder 21 for the nozzle 15 a little while after the purge gas valve 18a is changed from closed to open (step No. 5). It is also preferable to keep the spray gas valve 17a and the purge gas valve 18a open for a while after almost all the release agent slurry in the supply pipe 14 has been sprayed from the nozzle 15, so as to clean the inside of the supply pipe 14 and the nozzle 15 (step No. 6). Finally, the spray gas valve 17a and the purge gas valve 18a are changed from open to closed, completing the spraying of the release agent slurry to one mold C (step No. 7).

[0029] The composition of the gas used for the purge gas is not particularly limited as long as it does not substantially cause a chemical reaction with the material of the liquid-contacting parts such as the supply pipe 14 and the mold release agent slurry, and for example, compressed air or compressed nitrogen can be used, with compressed air being more suitable from the viewpoint of low cost. Note that Fig. 1 shows a case where the purge gas supply pipe 18 is branched off from the air header 16 for the miscellaneous gas, similar to the above-mentioned dispersion gas.

[0030] As shown in Fig. 3, the supply pipe 14 is cleaned after each cycle of spraying the release agent slurry in each mold C, so that the problem of clogging due to the release agent in the supply pipe 14 can be prevented. When using utility air as the dispersion gas or purge gas as described above, it is preferable to provide a filter-equipped pressure regulator in each of the jet gas supply pipe 17 and the purge gas supply pipe 18 as shown in Fig. 1 in order to further stabilize the amount of release agent slurry sprayed in each cycle of spraying the release agent slurry in each mold C. Similarly, when the slurry pump 12 is an air-driven diaphragm pump, it is preferable to provide a filter-equipped pressure regulator in the drive air pipe 19.

[0031] In the above-mentioned release agent slurry supply equipment, the supply pipe 14 is structured to branch off from the external circulation system, but it is also possible to connect the supply pipe directly to the storage tank 10 and provide a supply slurry pump different from the slurry pump 12 of the external circulation system in the supply pipe, thereby introducing the pressurized release agent slurry into the nozzle 15. Moreover, since the introduction of the release agent slurry into the supply pipe 14 is performed intermittently, it is preferable that the position of the spray valve 14a provided in the supply pipe 14 is as close as possible to the branch point P so that the release agent in the release agent slurry does not settle and separate in the supply pipe 14 and clog the inside of the pipe.

[0032] Instead of providing the spray valve 14a and the circulation cutoff valve 13a in the supply pipe 14 and the return pipe 13, respectively, as described above, a three-way valve serving both functions may be provided at the branch point P between the return pipe 13 and the supply pipe 14. The opening and closing of the circulation cutoff valve 13a, the spray valve 14a, the injection gas valve 17a, and the purge gas valve 18a are generally controlled by a control means 30 such as a CPU (Central Processing Unit) or a PLC (Programmable Logic Controller).

[0033] When relatively heavy particles such as barium sulfate are used as the release agent, which is the raw material of the release agent slurry, or when the solid content of the release agent slurry is high, that is, when the ratio of the release agent to the dispersion medium such as water is high, the fluidity of the release agent slurry decreases and the release agent slurry is likely to remain in the piping. However, even in such cases, the problems caused by the decrease in fluidity can be prevented by selecting a slurry pump having an appropriate pump head (water head) and capacity and by appropriately setting the supply pressure of the purge gas.

[0034] As described above, in the method for spraying a release agent slurry according to the embodiment of the present invention, the release agent slurry introduced from the storage tank 10 to the supply pipe 14 by the slurry pump 12 is sprayed from the nozzle 15 using the pressure of the purge gas instead of the discharge pressure of the slurry pump 12. Therefore, it becomes possible to control the amount of the release agent slurry sprayed in one cycle of spraying the release agent slurry on each mold C with great accuracy.

[0035] Furthermore, various release agents can be used with various solid content concentrations, for example, a release agent that has the property of adhering to the inner wall of a pipe over time can be used, or a release agent slurry with a relatively high solid content concentration can be used. Specifically, the range of the solid content concentration of the release agent slurry can be significantly expanded from the conventional range of about 30 to 60 g / L to about 20 to 160 g / L. In addition, the range of the spray amount of the release agent slurry can be significantly expanded from the conventional range of about 1500 to 2200 mL to about 500 to 3600 mL.

[0036] As described above, since a release agent slurry having a wide range of solid content concentration can be used, the degree of freedom in the spraying method is increased, and the spraying conditions of the release agent slurry can be optimized for various casting devices, which makes it possible to reduce the operating costs required for casting and improve the quality of the anode. For example, instead of the two-fluid nozzle that sprays the release agent slurry together with the above-mentioned dispersion gas, it becomes possible to use a general nozzle that sprays only the release agent slurry without the dispersion gas.

[0037] Furthermore, since the amount of the release agent slurry to be sprayed can be precisely adjusted, the conditions for spraying the release agent slurry can be optimized according to various conditions during the casting of the anode, and as a result, a high-quality anode with almost no unevenness such as bulges can be manufactured. For example, in cases where the temperature of the mold C is lower than usual and the water is difficult to evaporate before pouring, it is possible to use a release agent slurry with a high solid content.

[0038] In addition, the pressure of compressed air (plant air) available in a general factory may fluctuate due to intermittent use in other facilities in the factory. Conventionally, the amount of release agent slurry sprayed may change due to this pressure fluctuation. In contrast, in the release agent slurry supply equipment shown in FIG. 1, for example, the measured value of a pressure gauge installed in the air header is input to the control means 30, so that the opening and closing time of various automatic valves can be controlled according to the pressure fluctuation of the compressed air, making it possible to keep the spray amount almost constant. As a result, it is no longer necessary to deal with the fluctuation in the spray amount by spraying more than the amount required, which has been conventionally done, so that it is possible to improve the anode quality and reduce the consumption of the release agent.

[0039] The method for spraying the slurry according to the embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment and can include various modifications and alternatives within the scope of the present invention. For example, in the method for spraying the slurry according to the above embodiment, when the spray valve 14a is open, the release agent slurry is not sprayed from the nozzle 15 and all of it temporarily stays in the supply pipe 14, and the release agent slurry is sprayed from the nozzle 15 by introducing a purge gas into the supply pipe 14 after the spray valve 14a is switched from open to closed. However, the present invention is not limited to this, and as shown in FIG. 4, the release agent slurry may be sprayed from the nozzle 15 by switching the spray valve 14a from closed to open, and the release agent slurry remaining in the supply pipe 14 may be discharged from the nozzle 15 by introducing a purge gas into the supply pipe 14 after the spray valve 14a is switched from open to closed. EXAMPLES

[0040] (Example) In a copper electrolytic anode casting apparatus that repeats a cycle of pouring molten blister copper into a plurality of molds that are arranged at equal intervals in the circumferential direction on an intermittently rotating turntable, cooling and solidifying the molten blister copper, stripping the anodes solidified by cooling from the molds, and spraying a release agent slurry onto the molds after stripping, a release agent slurry supplying device as shown in Fig. 1 was used to spray the release agent slurry. The solid content concentration of the release agent slurry was changed in various ways within the range of 20 to 160 g / L, and the quality of the stripped anodes was visually confirmed.

[0041] An air-driven diaphragm pump was used for the slurry pump 12, a two-fluid nozzle was used for the nozzle 15, and general-purpose air was used for the driving air of the diaphragm pump, the dispersion gas introduced into the nozzle 15, and the purge gas introduced into the supply pipe 14, with the pressure in the air header always kept at about 500 kPa or more. The circulation cutoff valve 13a, the spray valve 14a, the injection gas valve 17a, and the purge gas valve 18a were opened and closed based on the timing chart of FIG. 3. As a result, it was found that a high-quality anode without blistering on the surface could be molded by appropriately adjusting the opening time of the spray valve 14a and the injection gas valve 17a even if the solid content concentration of the release agent slurry was changed within the range of 20 to 160 g / L.

[0042] (Comparative Example) The release agent slurry was filled into the suction cup only by the head pressure of the preparation tank of the release agent slurry, and then the release agent slurry was sprayed onto the mold of the casting device for the electrolytic anode similar to the above-mentioned embodiment by pressure-feeding it with air. As a result, the spray amount fluctuated due to the fluctuation of the water level in the release agent tank. In addition, since the spray amount was determined by the volume of the suction cup, it was impossible to increase the spray amount beyond the volume of the suction cup. Furthermore, since the release agent was pressure-fed by air, it was not possible to pressure-feed all of the release agent in the suction cup to the mold when the air pressure decreased, and the spray amount of the release agent varied. [Explanation of symbols]

[0043] 10 Reservoir 11 Extraction piping 12 Slurry pump 13 Return pipe 13a Circulation shutoff valve 14 Supply piping 14a Spray valve 15 Nozzles 16 Air Header 17 Injection gas supply pipe 17a Injection gas valve 18 Purge gas supply piping 18a Purge gas valve 19 Drive air piping 20 Servo motor 21 Cylinder 22 Piston 23 Shaft section 30 Control Means C mold P branch point

Claims

1. A method for spraying a release agent slurry, comprising the steps of: circulating the release agent slurry extracted from the bottom of a storage tank of the release agent slurry by an external circulation system which pressurizes the release agent slurry and returns the release agent slurry to the storage tank; and spraying the release agent slurry extracted into a supply pipe branching from the external circulation system onto a mold from a spraying means provided at the tip of the supply pipe, characterized in that the amount of the release agent slurry to be sprayed is adjusted depending on the time during which an automatic valve provided in the supply pipe is in an open state, and after the automatic valve is closed, a purge gas is introduced into the downstream side of the automatic valve to spray the release agent slurry in the supply pipe from the spraying means, and the release agent slurry is sprayed onto the mold by introducing the purge gas into the supply pipe.

2. 2. The method for spraying a release agent slurry according to claim 1, wherein the external circulation is stopped while the automatic valve is in an open state.

3. 3. The method for spraying a release agent slurry according to claim 1, wherein a spray flow rate of the release agent slurry is controlled by a pressure of the purge gas.

4. 4. A method for casting an anode, comprising the steps of: spraying a release agent slurry onto the mold by the method for spraying a release agent slurry according to any one of claims 1 to 3; pouring molten blister copper into the mold; cooling and solidifying the molten blister copper in the mold; and peeling off the anode molded by the solidification.

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