Method for separating and recovering rare earth component and metal component from post-calcination waste of multilayer ceramic capacitor

Abstract

The present invention provides a method for separating and recovering a rare earth component and a metal component from a post-calcination waste. This separation and recovery method includes: (A) a step for preparing a post-calcination waste of a multilayer ceramic capacitor in which a ceramic layer, an internal electrode layer containing a first metal component that has magnetic properties, and a baked electrode layer containing a second metal component that does not have magnetic properties are sintered; (B) a step for refining the post-calcination waste; (C) a step for separating and recovering, with use of a magnet, a first separated material that contains a refined ceramic and a refined first metal, and a second separated material that contains a refined ceramic, a rare earth-containing material, and a refined second metal; (D) a step for dissolving the second separated material into a mineral acid that has no oxidizing power, and precipitating the refined ceramic and the refined second metal, thereby generating a rare earth component-containing solution in which the rare earth component in the rare earth-containing material is dissolved; and (E) a step for dissolving the precipitate in the second separated material into ammonia water, thereby generating a second metal solution in which the second metal component in the refined second metal is dissolved.

Description

Method for separating and recovering rare earth and metal components from post-firing waste of multilayer ceramic capacitors

[0001] The present invention relates to a method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors.

[0002] Significant demand is expected for multilayer ceramic capacitors (MLCCs) as electronic components for automobiles, mobile phones, and the like. A multilayer ceramic capacitor includes a laminate having internal electrode layers and ceramic layers, and an external electrode. The internal electrode layers contain a metal component such as Ni, and the ceramic layers are formed from BaTiO3, for example. Patent Documents 1 to 4 disclose methods for recovering Ni, which is primarily used in the internal electrode layers, and also disclose that BaTiO3 contained in the ceramic layers is separated during the Ni recovery process.

[0003] Japanese Patent Application Laid-Open No. 2003-253347 Japanese Patent Application Laid-Open No. 2003-268459 Japanese Patent Application Laid-Open No. 2003-277843 Japanese Patent Application Laid-Open No. 2003-277846

[0004] Here, some raw materials used to manufacture multilayer ceramic capacitors contain not only Ni but also rare earth elements. Patent Documents 1 to 4 disclose the recovery of Ni, but do not disclose the recovery of rare earth elements. However, it is desirable to be able to recover not only metal elements such as Ni but also rare earth elements.

[0005] Therefore, a primary object of the present invention is to provide a method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors.

[0006] The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to the present invention comprises: (A) a step of preparing post-sintering waste of multilayer ceramic capacitors, the post-sintering waste comprising a laminate including ceramic layers and internal electrode layers, and fired electrode layers disposed on the laminate as outermost layers and connected to the internal electrode layers, the ceramic layers comprising aggregates of a plurality of ceramic particles, rare earth-containing materials containing rare earth components being contained in grain boundaries between the plurality of ceramic particles, the internal electrode layers comprising a first metal component which is a magnetic base metal, the fired electrode layers comprising a second metal component which is a non-magnetic noble metal, and the ceramic layers, the internal electrode layers, and the fired electrode layers being sintered; (B) a step of pulverizing the post-sintering waste to obtain a ceramic pulverized material in which the ceramic layers are pulverized, the rare earth-containing material, a first metal pulverized material in which the internal electrode layers are pulverized, and a second metal pulverized material in which the fired electrode layers are pulverized; (C) using a magnet to separate and recover the fired waste after step (B) into a first separated product containing the ceramic finely divided product and the first metal finely divided product, and a second separated product containing the ceramic finely divided product, the rare earth-containing material, and the second metal finely divided product; (D) dissolving the second separated product after step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic finely divided product and the second metal finely divided product in the second separated product and producing a rare earth component-containing solution in which the rare earth component in the rare earth-containing material has dissolved; and (E) dissolving the ceramic finely divided product and the second metal finely divided product in the second separated product precipitated in step (D) in ammonia water, thereby precipitating the ceramic finely divided product in the second separated product and producing a second metal solution in which the second metal component contained in the second metal finely divided product has dissolved.

[0007] According to this invention, rare earth elements and metal elements can be separated and recovered from the post-sintering waste, particularly the first metal element contained in the internal electrode layer and the second metal element contained in the external electrode.

[0008] The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to the present invention includes: (A) a step of preparing post-sintering waste of multilayer ceramic capacitors, the post-sintering waste comprising a laminate including ceramic layers and internal electrode layers, fired electrode layers disposed on the laminate and connected to the internal electrode layers, and a first-stage plating layer disposed on the fired electrode layer as an outermost layer, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth-containing matter containing a rare earth component is contained in grain boundaries between the plurality of ceramic particles, the internal electrode layer contains a first metal component which is a magnetic base metal, the fired electrode layer contains a second metal component which is a non-magnetic noble metal, the first-stage plating layer contains the first metal component, and the ceramic layers, the internal electrode layer, and the fired electrode layer are sintered; (B) a step of pulverizing the fired waste to obtain a ceramic fine-grained product in which the ceramic layer has been pulverized, a rare earth-containing material, a first metal fine-grained product in which the internal electrode layer and the first-stage plating layer have been pulverized, and a second metal fine-grained product in which the baked electrode layer has been pulverized; (C) a step of using a magnet to separate and recover the fired waste after the step (B) into a first separated product containing the ceramic fine-grained product and the first metal fine-grained product, and a second separated product containing the ceramic fine-grained product, the rare earth-containing material, and the second metal fine-grained product; (D) a step of dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine-grained product and the second metal fine-grained product in the second separated product and producing a rare earth component-containing solution in which the rare earth component in the rare earth-containing material has been dissolved; (E) dissolving the ceramic finely divided substance and the second metal finely divided substance in the second separated product precipitated in step (D) in ammonia water to precipitate the ceramic finely divided substance in the second separated product and to produce a second metal solution in which the second metal component contained in the second metal finely divided substance is dissolved.

[0009] According to this invention, rare earth elements and metal elements can be separated and recovered from the post-sintering waste, particularly the first metal element contained in the internal electrode layer and the second metal element contained in the external electrode.

[0010] The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to the present invention includes: (A) a step of preparing post-sintering waste of multilayer ceramic capacitors, the post-sintering waste comprising: a laminate including ceramic layers and internal electrode layers; baked electrode layers disposed on the laminate and connected to the internal electrode layers; a first-stage plating layer disposed on the baked electrode layers; and a second-stage plating layer disposed on the first-stage plating layer as an outermost layer, the ceramic layers having aggregates of a plurality of ceramic particles, and rare earth-containing materials containing rare earth components are contained in grain boundaries between the plurality of ceramic particles; the internal electrode layers contain a first metal component which is a magnetic base metal; the baked electrode layers contain a second metal component which is a non-magnetic noble metal; the first-stage plating layer contains the first metal component; and the second-stage plating layer contains a third metal component, and the ceramic layers, internal electrode layers, and baked electrode layers are sintered; (K) removing at least the second-stage plating layer from the fired waste, of the first-stage plating layer and the second-stage plating layer; (B) micronizing the fired waste from which at least the second-stage plating layer has been removed by going through step (K) to obtain a ceramic micronized product in which the ceramic layer has been micronized, a rare earth-containing material, a first metal micronized product in which the internal electrode layer and the first-stage plating layer have been micronized, and a second metal micronized product in which the baked electrode layer has been micronized; (C) using a magnet to separate and recover the fired waste after going through step (B) into a first separated product containing the ceramic micronized product and the first metal micronized product, and a second separated product containing the ceramic micronized product, the rare earth-containing material, and the second metal micronized product. (D) a step of dissolving the second separated product after step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the finely divided ceramic material and the finely divided second metal material in the second separated product and producing a rare earth component-containing solution in which the rare earth component in the rare earth-containing material has dissolved; (E) a step of dissolving the finely divided ceramic material and the finely divided second metal material in ammonia water, thereby precipitating the finely divided ceramic material in the second separated product and producing a second metal solution in which the second metal component contained in the finely divided second metal material has dissolved;Equipped with.

[0011] According to this invention, rare earth elements and metal elements can be separated and recovered from the post-sintering waste, particularly the first metal element contained in the internal electrode layer and the second metal element contained in the external electrode.

[0012] According to the present invention, it is possible to provide a method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors.

[0013] The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention, which proceeds with reference to the accompanying drawings.

[0014] 1 is a flow chart showing a method for separating and recovering rare earth components and metal components from waste after firing of a multilayer ceramic capacitor (firing for firing electrode layers) according to a first embodiment of the present invention. 2 is a cross-sectional view taken along line III-III in FIG. 2. 3 is a schematic diagram showing the state of unfired ceramic layers and unfired internal electrode layers in a multilayer chip in a cross section parallel to a plane including the length direction and stacking direction. 4 is an enlarged view of a portion α in FIG. 3, showing the state of each layer after firing for firing electrode layers. 5 is a partial enlarged view of the ceramic layer in FIG. 6. 7 is a cross-sectional view (1) parallel to a plane including the length direction and stacking direction of a multilayer ceramic capacitor according to a second embodiment of the present invention. 8 is a cross-sectional view (2) parallel to a plane including the length direction and stacking direction of another aspect of a multilayer ceramic capacitor according to the second embodiment of the present invention. 9 is a flow chart showing a method for separating and recovering rare earth components and metal components from waste after firing of a multilayer ceramic capacitor (firing for firing electrode layers), including a plating removal step.

[0015] <First embodiment> 1. Separation and recovery method A method for separating and recovering rare earth components and metal components (first metal component and second metal component) from post-sintering waste of multilayer ceramic capacitors (sintering for fired electrode layers) according to a first embodiment of the present invention will be described.

[0016] 1 is a flow diagram showing a method for separating and recovering rare earth elements and metal elements from post-sintering waste (sintering for fired electrode layers) of multilayer ceramic capacitors according to a first embodiment of the present invention. In the separation and recovery method according to the first embodiment of the present invention, post-sintering waste (sintering for fired electrode layers) of multilayer ceramic capacitors is used as the starting point for separation and recovery. The post-sintering waste will now be described.

[0017] (1) Post-Firing Waste Before explaining the post-firing waste, the multilayer ceramic capacitor manufactured in the manufacturing process of the multilayer ceramic capacitor and the manufacturing process thereof will be explained below.

[0018] (1-1) Multilayer Ceramic Capacitor Fig. 2 is an external perspective view showing an example of a multilayer ceramic capacitor according to a first embodiment of the present invention. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Here, a two-terminal multilayer ceramic capacitor will be described as an example of the multilayer ceramic capacitor 10.

[0019] As shown in FIGS. 2 and 3 , the multilayer ceramic capacitor 10 includes, for example, a rectangular parallelepiped laminate 12 and external electrodes 30 disposed on both ends of the laminate 12 .

[0020] The laminate 12 has a plurality of stacked ceramic layers 14 and a plurality of internal electrode layers 16 stacked on the ceramic layers 14. Furthermore, the laminate 12 has a first main surface 12a and a second main surface 12b facing each other in a height direction (stacking direction) x, a first side surface 12c and a second side surface 12d facing each other in a width direction y perpendicular to the height direction x, and a first end surface 12e and a second end surface 12f facing each other in a length direction z perpendicular to the height direction x and the width direction y. The ceramic layers 14 and the internal electrode layers 16 are stacked in the height direction x.

[0021] The first internal electrode layer 16 a and the second internal electrode layer 16 b can be made of, for example, a conductive material containing a magnetic base metal, and the magnetic base metal may be a simple metal or an alloy. Examples of magnetic base metals include Ni and Fe. Here, a metal that has a higher ionization tendency than hydrogen is referred to as a base metal.

[0022] The ceramic layer 14 comprises an aggregate of multiple ceramic particles (BTs in FIG. 5 , which will be described later and are also referred to as ceramic sintered bodies). Each ceramic particle can be formed, for example, from a dielectric material. Examples of such dielectric materials include perovskite-type compounds containing BaTiO 3 , CaTiO 3 , SrTiO 3 , or CaZrO 3 as the main component and dielectric ceramics having a perovskite structure. When the dielectric material is the main component, a rare earth element is added to the dielectric material as an additive depending on the desired characteristics of the laminate 12. Examples of the added rare earth element include at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu. The dielectric material may also contain minor components, such as Mn compounds, Fe compounds, Cr compounds, Co compounds, and Ni compounds, in amounts less than the main components. At least one of Si, Mg, Ba, and Mn may also be added to the main components as an additive. However, because these minor components and additives may cause a decrease in the quality of the rare earth components during separation and recovery, these minor components and additives may be omitted.

[0023] As shown in FIGS. 2 and 3, external electrodes 30 are disposed on the first end face 12e side and the second end face 12f side of the laminate 12.

[0024] The external electrode 30 includes a first external electrode 30a and a second external electrode 30b. The first external electrode 30a is connected to the first internal electrode layer 16a and is disposed on at least the surface of the first end face 12e. The second external electrode 30b is connected to the second internal electrode layer 16b and is disposed on at least the surface of the second end face 12f.

[0025] The external electrode 30 includes a fired electrode layer 32. The first external electrode 30a includes a first fired electrode layer 32a. The second external electrode 30b includes a second fired electrode layer 32b. In this embodiment, the fired electrode layer 32 is the outermost layer of the multilayer ceramic capacitor 10. In other words, the fired electrode layer 32 is the outermost layer of the layers disposed on the laminate 12.

[0026] The baked electrode layer 32 may be formed from a baked layer containing a glass component and a second metal component, which is a non-magnetic precious metal. The second metal component of the baked layer includes, for example, at least one element selected from Cu, Ag, etc. The glass component of the baked layer includes, for example, an oxide containing at least one element selected from B, Si, Ba, Mg, Al, Li, etc. Here, a metal with a lower ionization tendency than hydrogen is defined as a precious metal.

[0027] (1-2) Method for Manufacturing the Multilayer Ceramic Capacitor Next, a method for manufacturing the multilayer ceramic capacitor 10 will be described.

[0028] (Step 1) First, a dielectric sheet for the ceramic layer and a conductive paste for the internal electrode layer are prepared. The dielectric sheet for the ceramic layer is formed from a dielectric slurry containing, for example, but not limited to, BaTiO3 as a main component and Dy as an additive. The conductive paste for the internal electrode layer is formed from, for example, but not limited to, Ni as a main component. The dielectric sheet and the conductive paste for the internal electrode layer contain a binder and a solvent. The binder and solvent are composed of a resin component, and various known thermosetting resins such as epoxy resin, phenoxy resin, phenolic resin, urethane resin, and polyimide resin can be used as the resin component.

[0029] (Step 2) Then, a conductive paste for the internal electrode layers is printed in a predetermined pattern on the dielectric sheet by, for example, screen printing, gravure printing, etc. In this way, a dielectric sheet on which the pattern of the first internal electrode layer is formed, and a dielectric sheet on which the pattern of the second internal electrode layer is formed are prepared.

[0030] Furthermore, with regard to the dielectric sheets, outer layer dielectric sheets on which no internal electrode layer patterns are printed are also prepared.

[0031] A predetermined number of dielectric sheets for outer layers, on which no pattern of internal electrode layers is printed, are stacked. A dielectric sheet on which a pattern of a first internal electrode layer is printed and a dielectric sheet on which a pattern of a second internal electrode layer is printed are sequentially stacked on top of the dielectric sheets to form a portion that will become an internal layer portion. A predetermined number of dielectric sheets for outer layers, on which no pattern of an internal electrode layer is printed, are stacked on top of the portion that will become an internal layer portion. This forms a laminated sheet having an internal layer portion and an external layer portion. The dielectric sheets may also be referred to as unfired ceramic layers, i.e., ceramic layers before firing of the laminated chip. The pattern of the internal electrode layers may also be referred to as unfired internal electrode layers, i.e., internal electrode layers before firing of the laminated chip.

[0032] (Step 3) Next, the laminated sheet is pressed in the lamination direction by means of a hydrostatic press or the like to produce a laminated block.

[0033] (Step 4) The laminated block is then cut to a predetermined size to produce laminated chips. FIG. 4 is a schematic diagram showing the state of the unfired ceramic layers and unfired internal electrode layers in a cross section of the laminated chip parallel to a plane including the longitudinal direction and the lamination direction. FIG. 4 shows a cross section of the laminated chip on which the external electrodes 30 have not yet been formed. The laminated chip in FIG. 4 is in a state prior to degreasing (step 5) and firing (step 6). The resin component contained in the laminated chip is not shown. As shown in FIG. 4, the laminated chip is formed by alternately stacking unfired internal electrode layers 16_U and unfired ceramic layers 14_U.

[0034] The laminated chip as a whole contains a first metal powder (Ni_P in FIG. 4), ceramic powders (BT_P, BT_P in FIG. 4), rare earth powder (Dy_P in FIG. 4), and a resin component. The first metal powder mainly constitutes the internal electrode layer 16_U when unsintered. The ceramic powder mainly constitutes the ceramic layer 14_U when unsintered.

[0035] The first metal powder is, for example, an aggregate of first metal atoms, which is the first metal component. As described above, the first metal powder can be composed of a conductive material containing a magnetic base metal, and the magnetic base metal can be a simple metal or an alloy. Examples of magnetic base metals include Ni and Fe.

[0036] The ceramic powder is an aggregate of dielectric materials. As described above, examples of the dielectric materials include BaTiO3, CaTiO3, SrTiO3, and CaZrO3. The ceramic powder includes a first ceramic powder and a second ceramic powder. The second ceramic powder has a smaller particle size than the first ceramic powder.

[0037] The rare earth powder is an aggregate of rare earth atoms, which are rare earth components. As described above, the rare earth atoms can be at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0038] The resin components are binders and solvents for producing conductive pastes for the dielectric sheets and internal electrode layers. The binders and solvents contain resin components, and various known thermosetting resins such as epoxy resins, phenoxy resins, phenolic resins, urethane resins, and polyimide resins can be used as the resin components.

[0039] The state of the powder in the laminated chip will be further explained using FIG. 4. The schematic diagram in FIG. 4 shows the state of various powders contained in the laminated chip before degreasing (step 5) and firing (step 6). Note that the resin component is omitted from FIG. 4. As shown in FIG. 4, in this embodiment, the unfired ceramic layer 14_U is primarily composed of a first ceramic powder (BT1_P in FIG. 4). Furthermore, in the unfired ceramic layer 14_U, the first ceramic powder and the rare earth powder (Dy_P in FIG. 4) are at least partially adhered to each other. As shown in the example in FIG. 4, the rare earth powder is primarily adhered to the surface of the first ceramic powder, and is not essentially chemically bonded to the interior of the first ceramic powder. Furthermore, in this embodiment, the unfired internal electrode layer 16_U is primarily composed of a first metal powder (Ni_P in FIG. 4). In the unsintered internal electrode layer 16_U, the first metal powder and the second ceramic powder (BT2_P in FIG. 4) are at least partially adhered to each other. As shown in the example of FIG. 4, the second ceramic powder is primarily adhered to the surface of the first metal powder, and is not essentially chemically bonded to the first metal powder by penetrating into the first metal powder. The term "adhered" may also include partial chemical bonding between powders such as the first metal powder, ceramic powder, and rare earth powder. Note that chemical bonding refers to bonding between multiple atoms, such as ionic bonds, covalent bonds, and metallic bonds, in which positive and negative charges attract and bind each other.

[0040] (Step 5) Next, the resin components in the stacked chips are removed. Hereinafter, the removal of the resin components in step 5 is a degreasing step in the manufacturing process. The degreasing temperature in step 5 is, for example, higher than 800°C and lower than 1000°C.

[0041] (Step 6) Next, the laminated chip is fired to produce the laminate 12. The firing temperature for the laminated chip depends on the materials of the ceramic layers and internal electrode layers, which are dielectrics, but is preferably, for example, higher than 1000°C and lower than 1400°C. Steps 1 to 6 constitute the laminate formation process. The firing in step 6 may also be referred to as firing the laminated chip. This firing turns the unfired laminated chip into the laminate 12. Furthermore, the unfired internal electrode layers 16_U and the unfired ceramic layers 14_U are fired to become the internal electrode layers 16 and the ceramic layers 14.

[0042] (Step 7) Next, a baked electrode layer paste containing a plurality of second metal powders (e.g., Cu powder) is applied to the first and second end faces 12e, 12f of the laminate 12 and fired to form baked electrode layers 32, which are external electrodes 30. The second metal powder is, for example, an aggregate of second metal atoms, which is the second metal component. Each second metal powder in the baked electrode layer paste is dispersed singly or in contact with other powders, including other second metal powders. In other words, each second metal powder in the baked electrode layer paste is not chemically bonded to other second metal powders or powders of other additives. The baked electrode layer paste is then fired, resulting in a sintered state of the second metal powders. The firing temperature of the baked electrode layer paste is preferably 700°C or higher and 900°C or lower. The firing in step 7 is sometimes referred to as firing for the baked electrode layer.

[0043] Next, the state of each layer of the multilayer ceramic capacitor 10 after firing for the fired electrode layers in (Step 7) will be described. Fig. 5 is an enlarged view of the a portion in Fig. 3, and is a schematic diagram showing the state of each layer after firing for the fired electrode layers. Fig. 6 is a partial enlarged view of the ceramic layer in Fig. 5. After firing for the fired electrode layers, the multilayer ceramic capacitor 10 is in a sintered state with each portion, such as the ceramic layers 14, internal electrode layers 16, and external electrodes 30.

[0044] In the ceramic layer 14, the ceramic powder (BT_P, BT_P in FIG. 4 ) undergoes firing to become ceramic particles BT (BT in FIG. 5 ) in a sintered state, as shown in FIG. 5 . The ceramic powder (BT_P, BT_P in FIG. 4 ) undergoes firing of the laminated chip, for example, in step 6, to form sintered ceramic particles BT. The sintered ceramic particles BT are sometimes referred to as ceramic sintered bodies BT. For example, firing of ceramic powders evolves the contact between the ceramic powder particles from point contact to surface contact. This promotes chemical bonding between the ceramic powder particles, forming integrated ceramic particles BT (ceramic sintered bodies BT). The ceramic particles BT may be formed by partial chemical bonding of the ceramic powder with the rare earth powder. In the example of FIG. 5 , the ceramic layer 14 includes an aggregate of multiple ceramic particles BT. Note that most of the first ceramic powder (BT1_P in FIG. 4) forms the ceramic layer 14, for example, by undergoing firing of the laminated chip in (Step 6). Also, most of the second ceramic powder (BT1_P in FIG. 4) adhering to the first metal powder (Ni_P in FIG. 4) forms the ceramic layer 14, for example, by undergoing firing of the laminated chip in (Step 6). At this time, most of the second ceramic powder (BT1_P in FIG. 4) is not basically bonded to the fired internal electrode layer 16, but is pushed out from the fired internal electrode layer 16, and is fired together with the first ceramic powder to form the ceramic layer 14.

[0045] Further describing the ceramic layer 14, each ceramic particle BT is formed of a core-shell 40 as shown in FIG. 6 . The core-shell 40 includes a core portion 42 including a central portion of the core-shell 40 and a shell portion 44 covering the surface of the core portion 42. The core portion 42 is primarily formed of a ceramic material. The shell portion 44 is formed by incorporating, for example, a rare earth component as an additive into the ceramic material. The shell portion 44 may also incorporate other minor components such as Mn compounds. Grain boundaries 50 exist at the boundaries between the ceramic particles BT. The grain boundaries 50 contain rare earth inclusions. The rare earth inclusions contain the rare earth component, for example, in the form of an oxide. An example of the oxide of the rare earth component is dysprosium oxide (DyO). The rare earth inclusions may also contain, for example, silicon dioxide (SiO), manganese dioxide (MnO), etc. Note that the above description has been given regarding the core-shell structure of each ceramic particle BT. However, each ceramic particle BT may have a structure in which the rare earth element or the like is incorporated up to the center of the ceramic particle BT. Furthermore, ceramic particles BT having such a structure and ceramic particles BT having a core-shell structure may be mixed in the ceramic layer 14.

[0046] The internal electrode layer 16 is formed by firing the first metal powder (Ni_P in FIG. 4 ) to form first metal particles (Ni in FIG. 5 ) in a sintered state as shown in FIG. 5 . The first metal powder (Ni_P in FIG. 4 ) is fired, for example, to form the sintered internal electrode layer 16 by firing the laminated chip (step 6). In FIG. 5 , Ni powder, which is the first metal powder, is sintered to form Ni particles (first metal particles). The sintered first metal particles are sometimes referred to as a first metal sintered body. For example, when the first metal powder is heated by firing, the contact between the first metal powder particles develops from point contact to surface contact. This progresses the bonding between the first metal powder particles, forming integrated first metal particles (first metal sintered body). In the example of FIG. 5 , the internal electrode layer 16 includes an aggregate of multiple first metal particles.

[0047] In the baked electrode layer 32 (external electrode 30), a second metal powder (e.g., Cu powder) undergoes firing for the baked electrode layer, becoming second metal particles (Cu in FIG. 5) in a sintered state as shown in FIG. 5 . In FIG. 5 , the Cu powder, which is the second metal powder, is sintered to become Cu particles (second metal particles). The second metal particles in a sintered state are sometimes referred to as second metal sintered bodies. For example, when the second metal powder is heated during firing for the baked electrode layer, contact between the second metal powder particles develops from point contact to surface contact. This progresses bonding between the second metal powder particles, forming integrated second metal particles (second metal sintered bodies). In the example of FIG. 5 , the baked electrode layer 32 includes an aggregate of multiple second metal particles.

[0048] The multilayer ceramic capacitor 10 is manufactured by the above-described manufacturing process.

[0049] Here, in the present embodiment, the post-firing waste refers to waste generated after the firing of the fired electrode layers in (step 7) when the multilayer ceramic capacitor 10 is manufactured by the above-described manufacturing method for the multilayer ceramic capacitor 10.

[0050] (2) Flow of Separation and Recovery Method The flow of the separation and recovery method according to the first embodiment of the present invention will be described with reference to Figure 1. The separation and recovery method of Figure 1 includes a common separation and recovery route, a separation and recovery route for rare earth components, a separation and recovery route for a first metal component, and a separation and recovery route for a second metal component. The separation and recovery route for the rare earth components and the separation and recovery route for the first metal component branch off from the common separation and recovery route. The separation and recovery route for the second metal component branches off from the separation and recovery route for the rare earth components.

[0051] The common separation and recovery route may include, for example, preparation of post-calcination waste in step (A), pulverization in step (B), and magnetic separation in step (C). After magnetic separation in step (C), the process branches into a separation and recovery route for the rare earth component and a separation and recovery route for the first metal component. The separation and recovery route for the rare earth component may include, for example, dissolution of the second separated material in step (D), and further include filtration in step (F) and neutralization in step (G). Furthermore, after filtration in step (F), the separation and recovery route for the second metal component branches off from the separation and recovery route for the rare earth component. The separation and recovery route for the second metal component may include, for example, dissolution of the undissolved material in step (E), and further include filtration in step (H). The separation and recovery route for the first metal component may include, for example, dissolution of the first separated material in step (I), and further include filtration in step (J).

[0052] (Step (A): Preparation of Firing Waste) In step (A), post-firing waste (firing for fired electrode layers) of a multilayer ceramic capacitor is prepared. The post-firing waste is as described above. The post-firing waste includes a laminate 12 including ceramic layers 14 and internal electrode layers 16, and fired electrode layers 32. The ceramic layers 14, internal electrode layers 16, and fired electrode layers 32 are in a sintered state.

[0053] (Step (B): Refining) In step (B), the fired waste is refined. For example, but not limited to, the fired waste is pulverized by pulverization. The pulverization can be performed by, but not limited to, a method of applying a pulverizing force by vibration to the object using a vibrating mill or the like, a method of grinding the object, a method of applying a pulverizing force by impact to the object, or the like. It is preferable to refine the fired waste to an extent that it can be easily separated in the magnetic separation in step (C) described below. By refining the fired waste, it is possible to obtain a ceramic refined product obtained by refining the sintered ceramic layer 14, a sintered rare earth-containing material, a first metal refined product obtained by refining the sintered internal electrode layer 16, and a second metal refined product obtained by refining the sintered baked electrode layer 32. The ceramic refined product includes, for example, a ceramic material such as BaTiO3, CaTiO3, SrTiO3, or CaZrO3. The rare earth-containing material may include, for example, dysprosium oxide (DyO), and may also include, for example, silicon dioxide (SiO), manganese dioxide (MnO). The first finely divided metal material may include, for example, a first metal component such as Ni and Fe. The second finely divided metal material may include, for example, a second metal component such as Cu. The average particle size of the post-calcination waste after being reduced in size is not limited. The average particle size can be determined, for example, using a sieve.

[0054] (Step (C): Magnetic Separation) In the magnetic separation of step (C), the post-sintered waste after being pulverized in step (B) is magnetically separated using a magnet. That is, by magnetic separation, the post-sintered waste is separated into a first separated product and a second separated product and recovered.

[0055] The first separated material includes a first metal fine particle (Ni in FIG. 1 ) and a ceramic fine particle (BT in FIG. 1 ). The first metal fine particle includes a first metal component, which is a magnetic base metal. On the other hand, the ceramic fine particle is not magnetic. By magnetic separation, the first separated material is separated as a magnetic substance. Specifically, in the first separated material, when the magnetic first metal fine particle is separated as a magnetic substance, the non-magnetic ceramic fine particle is caught in the first metal fine particle.

[0056] The second separated material includes a second metal fine particle (Cu in FIG. 1), a rare earth-containing material (Dy2O3 in FIG. 1), and a ceramic fine particle (BT in FIG. 1). The second metal fine particle contains a second metal component, which is a non-magnetic precious metal. The rare earth-containing material and the ceramic fine particle are non-magnetic. Therefore, the second metal fine particle, the rare earth-containing material, and the ceramic fine particle are separated as non-magnetic materials by magnetic separation.

[0057] Therefore, by this magnetic separation, the second separated material is removed from the post-sintering waste, and the first separated material containing the first metal fine particles can be separated and recovered as the first metal component. For example, the first metal fine particles are finely divided Ni (the first metal component) that constitutes the internal electrode layer 16 in a sintered state. In the present invention, the separation and recovery of the first metal component includes not only the separation and recovery of the first metal component itself, but also the separation and recovery of the first separated material containing the first metal fine particles as the first metal component.

[0058] The first metal component includes the first metal atom itself, a first metal component compound which is a reaction product of the first metal atom chemically reacting with other atoms, a solution of the first metal atom, a solution of the first metal component compound, etc. The state of the first metal component may be any of a liquid state, a solid state, or a mixed state of liquid and solid. The first metal component may be any of an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline.

[0059] In other words, by this magnetic separation, the second fine metal material and the rare earth-containing material can be separated and recovered from the post-burning waste, with the first separated material removed.

[0060] In addition, during magnetic separation, it is preferable to mix and disperse the post-calcination waste after being pulverized in step (B) with an aqueous solvent such as water to create a mixed state, and then separate it using a magnet.

[0061] When the pulverized calcined waste is mixed with an aqueous solvent to form a mixed state, i.e., a slurry state, the ceramic pulverized material, rare earth-containing material, first metal pulverized material, and second metal pulverized material contained in the pulverized calcined waste can be dispersed. Therefore, in step (C), the first separated material and the second separated material can be easily separated using a magnet. When the pulverized calcined waste is in a dry state, the first separated material and the second separated material tend to be less dispersed than when in a slurry state. Therefore, for example, when the first separated material is attracted to a magnet, the second separated material may become entangled in the first separated material and be attracted to the magnet, making it difficult to separate the first separated material and the second separated material.

[0062] (Step (D): Dissolution of Second Separation Product) In step (D), the second separation product separated and recovered in step (C) is dissolved in a mineral acid with no oxidizing power. This allows for the production of a rare earth component-containing solution in which the rare earth components of the rare earth-containing material contained in the second separation product are dissolved. Therefore, the rare earth component-containing solution can be separated and recovered as a rare earth component. At this time, the ceramic fine particles and the second metal fine particles in the second separation product are precipitated. The ceramic fine particles react with the mineral acid with no oxidizing power and precipitate as undissolved matter. Furthermore, the second metal fine particles, such as Cu, do not dissolve in the mineral acid with no oxidizing power because they have a lower ionization tendency than the hydrogen ions contained in the mineral acid with no oxidizing power. The mineral acid with no oxidizing power is, for example, at least one selected from the group including dilute sulfuric acid and hydrochloric acid.

[0063] As described above, the rare earth component is separated and recovered as a rare earth component-containing solution. In the present invention, the separation and recovery of the rare earth component includes not only the separation and recovery of the rare earth component itself, but also the separation and recovery of the rare earth component-containing solution as the rare earth component. In other words, the rare earth component includes rare earth atoms themselves, rare earth component compounds which are reaction products of rare earth atoms chemically reacting with other atoms, solutions of rare earth atoms, solutions of rare earth component compounds, etc. Furthermore, the rare earth component may be in any of a liquid state, a solid state, or a mixed state of liquid and solid. Furthermore, the rare earth component may be in any of an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline.

[0064] In step (D), it is preferable to adjust the pH of the rare earth component-containing solution to 1.5 or more and 2.5 or less by adding a mineral acid having no oxidizing power.

[0065] In step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or higher and 2.5 or lower using a non-oxidizing mineral acid, thereby dissolving mainly the rare earth components in the rare earth-containing material in the non-oxidizing mineral acid. Furthermore, adjusting the pH to a stronger acid than the above range may result in the ceramic fine particles being dissolved in the non-oxidizing mineral acid, so it is preferable to adjust the pH to within the above range. More preferably, the rare earth component-containing solution is adjusted to a pH of 2 by adding a non-oxidizing mineral acid.

[0066] When the post-calcination waste in a slurry state is subjected to magnetic separation in step (C), the separated second separated material is in a slurry state with a pH of about 7. By adding a mineral acid with no oxidizing power to this slurry, it is also possible to produce a rare earth component-containing solution with an adjusted pH of 1.5 or more and 2.5 or less. However, the second separated material after magnetic separation does not need to be in a slurry state and may be in a dry state.

[0067] When the ceramic fine particles contained in the second separated material are, for example, BaTiO3, dilute sulfuric acid is preferably used as the non-oxidizing mineral acid. When dilute sulfuric acid is used, insoluble BaSO4 is formed on the surface of the BaTiO3 ceramic fine particles, allowing the ceramic fine particles to precipitate. Note that second metal fine particles, such as Cu, have a lower ionization tendency than the hydrogen ions contained in the non-oxidizing mineral acid and therefore do not dissolve in the non-oxidizing mineral acid. On the other hand, rare earth powder can be dissolved in dilute sulfuric acid. Specifically, for example, when a second separated material mainly containing Cu second metal fine particles, a rare earth-containing material such as DyO3, and a BaTiO3 ceramic fine particle is dissolved in dilute sulfuric acid, BaTiO3 precipitates and Cu does not dissolve. Meanwhile, a dysprosium sulfate (Dy(SO)3) solution, in which Dy from the rare earth-containing material is dissolved in dilute sulfuric acid, is produced as a rare earth component-containing solution.

[0068] As mentioned above, hydrochloric acid or the like can be used as the non-oxidizing mineral acid in addition to dilute sulfuric acid. However, if hydrochloric acid is used as the non-oxidizing mineral acid, soluble BaCl is formed on the surface of the finely divided ceramic material, BaTiO. Therefore, it is preferable to precisely adjust the pH of the hydrochloric acid or the like so as to precipitate the finely divided ceramic material and dissolve the rare earth-containing material while leaving the finely divided second metal material undissolved.

[0069] (Step (F): Filtration) In step (F), the rare earth component-containing solution containing the precipitated ceramic fine particle and the undissolved second metal fine particle produced in step (D) is filtered to separate the undissolved ceramic fine particle and the second metal fine particle from the rare earth component-containing solution. By this solid-liquid separation, the rare earth component-containing solution from which the undissolved ceramic fine particle and the second metal fine particle have been removed can be separated and recovered as rare earth components from the rare earth component-containing solution containing the undissolved ceramic fine particle and the second metal fine particle.

[0070] For example, in step (D), BaTiO is precipitated, and the finely divided second metal particles such as Cu are not dissolved, and a dysprosium sulfate (Dy(SO)) solution containing Dy dissolved in dilute sulfuric acid is produced as a rare earth component-containing solution. In this case, the dysprosium sulfate solution from which BaTiO and Cu have been removed can be separated and recovered as rare earth components by filtration in step (F).

[0071] The filtration can be carried out using filter paper (filter cloth). The mesh size of the filter paper (filter cloth) is preferably such that the undissolved ceramic fine product and the second metal fine product do not pass through the filter paper (filter cloth).

[0072] The rare earth component-containing solution containing the undissolved ceramic fine product and the second metal fine product produced in step (D) can be solid-liquid separated, and the solid-liquid separation is not limited to filtration, and can be performed by any known method appropriately selected from decantation, centrifugation, etc. Filtration is more preferred.

[0073] (Step (G): Neutralization) In step (G), the rare earth component-containing solution obtained in step (F) is neutralized to precipitate and recover the rare earth component. The precipitated rare earth component is separated and recovered, for example, by filtering the neutralized rare earth component-containing solution. At this time, the rare earth component is separated and recovered as a rare earth component compound (e.g., Dy(OH)3, etc.) by neutralization. In the present invention, separation and recovery of the rare earth component includes not only the separation and recovery of the rare earth component itself, but also the separation and recovery of a rare earth component compound, which is a reaction product of a chemical reaction of the rare earth component, as the rare earth component.

[0074] An alkali is used for neutralization. Examples of alkalis include sodium hydroxide and potassium hydroxide. Although the pH range in which rare earth components precipitate can change when the redox potential changes, using these alkalis can stabilize the pH range in which rare earth components precipitate.

[0075] In the neutralization step (G), the rare earth component is recovered by adjusting the pH of the rare earth component-containing solution to a value between 6 and 9. This allows the precipitate resulting from the neutralization reaction to be efficiently separated and recovered as the rare earth component. More preferably, the rare earth component-containing solution is adjusted to a pH of 8 by adding an alkali.

[0076] For example, when a dysprosium sulfate solution from which BaTiO3, Cu, and the like have been removed is obtained in the filtration of step (F), dysprosium hydroxide (Dy(OH)3) is obtained as a rare earth component compound by neutralization with sodium hydroxide. That is, since the dysprosium sulfate solution is acidic, neutralization with an alkali allows the rare earth component dysprosium to precipitate as dysprosium hydroxide (Dy(OH)3), which can be separated and recovered. Here, dysprosium hydroxide (Dy(OH)3) can be separated and recovered by filtering the dysprosium sulfate solution neutralized with an alkali. In addition to filtration, known methods such as decantation and centrifugation can also be used.

[0077] Note that some metal components (so-called contaminants) are not separated as the first separated product in the magnetic separation in step (C) but are entrained in the second separated product. Therefore, the rare earth component-containing solution produced by dissolving the second separated product in step (D) may contain contaminating metal components. These metal components include, for example, Ti, Mn, and Ni. Then, in step (G), Ti, Mn, and the like can be separated and recovered by adding an alkali to the rare earth component-containing solution to adjust the pH to, for example, between 3 and 5, preferably about 4. In this case, Ti precipitates as, for example, Ti(OH)4, and Mn precipitates as, for example, Mn(OH)2. Therefore, Ti(OH)4, Mn(OH)2, and the like are recovered by filtering the rare earth component-containing solution adjusted to about pH 4.

[0078] Thereafter, an alkali is further added to the solution containing the rare earth elements from which Ti, Mn, etc. have been separated, and the pH is adjusted to between 6 and 9, preferably about 8, as described above, to separate and recover the rare earth elements.

[0079] Thereafter, Ni and other components can be separated and recovered by adding an alkali to the solution from which Ti, Mn, rare earth components, etc. have been separated, and adjusting the pH to, for example, more than pH 9 but not more than pH 11, preferably about pH 10. In this case, Ni precipitates as, for example, Ni(OH)2. The solution adjusted to about pH 10 is filtered to recover Ni(OH)2 and other components.

[0080] By repeating stepwise neutralization and filtration in this manner, various components (contaminants, rare earth components, etc.) contained in the rare earth component-containing solution can be separated and recovered.

[0081] Furthermore, in the stepwise neutralization of the rare earth component-containing solution as described above, the rare earth component-containing solution is neutralized to a pH of 3 or more and 5 or less, preferably about pH 4, before separating the rare earth component. This allows contaminants such as Ti and Mn to be first removed from the rare earth component-containing solution. Since contaminants such as Ti and Mn have been removed from the rare earth component-containing solution in this manner, it is possible to further facilitate separation of the rare earth component using the rare earth component-containing solution in a state in which these contaminants have been removed.

[0082] (Step (E): Dissolution of Undissolved Material) In step (E), the finely divided ceramic material and the finely divided second metal material removed by filtration in step (F) are dissolved in ammonia water. This produces a second metal solution in which the second metal component contained in the finely divided second metal material is dissolved. Therefore, the second metal component can be separated and recovered from the second metal solution. At this time, the finely divided ceramic material is precipitated.

[0083] Specifically, a second metal fine particle containing a second metal component such as Cu and a ceramic fine particle of BaTiO are dissolved in ammonia water. 2+ A second metal solution containing ammine copper complexes such as BaTiO3 precipitates in the second metal solution.

[0084] As described above, the second metal component is separated and recovered as a second metal solution. In the present invention, separation and recovery of the second metal component includes not only the separation and recovery of the second metal component itself, but also the separation and recovery of the second metal component solution as the second metal component. Here, the second metal component includes the second metal component itself, a second metal component compound which is a reaction product of the second metal component chemically reacting with other atoms, a solution of the second metal component, a solution of the second metal component compound, etc. Furthermore, the state of the second metal component may be any of a liquid state, a solid state, or a mixed state of liquid and solid. Furthermore, the second metal component may be any of an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline.

[0085] In step (E), it is preferable to adjust the second metal solution to a pH of 9 or more and a pH of 10 or less by adding aqueous ammonia. By adjusting the second metal solution to a pH of 9 or more and a pH of 10 or less in step (E), the second metal solution can be efficiently separated and recovered as the second metal component. More preferably, the second metal solution is adjusted to a pH of 9.5 by adding aqueous ammonia.

[0086] Furthermore, when the undissolved ceramic fine particles and the second metal fine particles extracted in step (F) are dissolved in ammonia water, it is preferable to add an ammonium salt, such as ammonium sulfate, to the ammonia water. Here, the ammonia water serves as a source of ammonia for forming an ammine complex, such as a copper ammine complex, with the second metal component, such as Cu. The ammonium salt also provides a counterion to the ammine complex, such as a copper ammine complex. For example, an ammonium salt, such as ammonium sulfate, can be used to dissolve [Cu(NH3)4] 2+ The copper ammine complex is treated with SO4 as a counter ion. 2- Even if the concentration of ammonia decreases, salts such as CuSO4 are formed, suppressing the deposition of Cu ions.

[0087] (Step (H): Filtration) In step (H), the second metal solution containing the precipitated ceramic microparticles produced in step (E) is filtered to separate the precipitated ceramic microparticles from the second metal solution. This solid-liquid separation allows the second metal solution, from which the precipitated ceramic microparticles have been removed, to be separated and recovered as a second metal component.

[0088] For example, in step (E), in a state where BaTiO3 is precipitated, a second metal solution is generated in which a second metal component such as Cu is dissolved in ammonia water. The second metal solution may be, for example, [Cu(NH3)4] 2+ In this case, the second metal solution containing the copper ammine complex from which BaTiO3 has been removed by filtration in step (H) can be separated and recovered as the second metal component.

[0089] Filtration can be carried out using filter paper (filter cloth). The mesh size of the filter paper (filter cloth) is preferably such that the precipitated ceramic microparticles do not pass through the filter paper (filter cloth). In addition, the solid-liquid separation of the second metal solution containing the precipitated ceramic microparticles produced in step (E) is not limited to filtration, and solid-liquid separation can be carried out by a method appropriately selected from known methods such as decantation and centrifugation. Filtration is more preferred.

[0090] (Step (I): Dissolution of First Separation Product) In step (I), the first separation product separated and recovered in step (C) is dissolved in a mineral acid. The first separation product contains a first metal finely divided product and a ceramic finely divided product. By dissolving the first separation product in the mineral acid, the ceramic finely divided product contained in the first separation product is precipitated as an undissolved product, and a first metal solution is produced in which the first metal finely divided product in the first separation product is dissolved. At this time, the first metal component contained in the first metal finely divided product is separated and recovered as a first metal solution. In the present invention, separation and recovery of the first metal component includes not only the separation and recovery of the first metal component itself, but also the separation and recovery of the first metal solution as the first metal component. The mineral acid is, for example, at least one selected from the group including sulfuric acid, nitric acid, and hydrochloric acid. The mineral acid may be either a mineral acid with or without oxidizing power. In the present embodiment, the term "mineral acid" simply refers to both mineral acids that have oxidizing power and mineral acids that do not have oxidizing power.

[0091] In step (I), it is preferable to adjust the pH of the first metal solution to 1.5 or more and 2.5 or less by adding a mineral acid.

[0092] In step (I), the first metal solution is adjusted to a pH of 1.5 or higher and a pH of 2.5 or lower using a mineral acid, thereby dissolving the first metal component in the first metal fine powder in the mineral acid. Furthermore, adjusting the pH to a stronger acid than the above range may result in the ceramic fine powder dissolving in the mineral acid, so it is preferable to adjust the pH to within the above range. More preferably, the first metal solution is adjusted to a pH of 2 by adding a mineral acid.

[0093] When the post-calcination waste in a slurry state is subjected to magnetic separation in step (C), the separated first separated material is in a slurry state with a pH of about 7. By adding a mineral acid to this slurry, it is also possible to produce a first metal solution with an adjusted pH of 1.5 or more and 2.5 or less. However, the first separated material after magnetic separation does not need to be in a slurry state and may be in a dry state.

[0094] When the ceramic fine particles contained in the first separated material are, for example, BaTiO3, sulfuric acid is preferably used as the mineral acid. When sulfuric acid is used, insoluble BaSO4 is formed on the surface of the BaTiO3 ceramic fine particles, thereby precipitating the ceramic fine particles. Meanwhile, a first metal fine particle such as Ni can be dissolved in sulfuric acid. Specifically, for example, by dissolving a first separated material mainly containing Ni first metal fine particles and BaTiO3 ceramic fine particles in sulfuric acid, BaTiO3 is precipitated, and a nickel sulfate (NiSO4) solution in which Ni is dissolved in sulfuric acid is produced as the first metal solution.

[0095] As mentioned above, the mineral acid may be other than sulfuric acid, such as hydrochloric acid. However, if hydrochloric acid is used as the mineral acid, soluble BaCl is formed on the surface of the finely divided ceramic material, BaTiO. Therefore, it is preferable to precisely adjust the pH of the hydrochloric acid or the like so as to precipitate the finely divided ceramic material and dissolve the first finely divided metal material.

[0096] (Step (J): Filtration) In step (J), the first metal solution containing the precipitated fine ceramic material produced in step (I) is filtered to separate the precipitated fine ceramic material from the first metal solution. By this solid-liquid separation, the first metal solution from which the precipitated fine ceramic material has been removed can be separated and recovered as a first metal component from the first metal solution containing the precipitated fine ceramic material.

[0097] For example, in step (I), BaTiO is precipitated and a nickel sulfate (NiSO) solution in which Ni is dissolved in sulfuric acid is produced as the first metal solution. In this case, the nickel sulfate solution from which BaTiO has been removed can be obtained by filtration.

[0098] Filtration can be performed using filter paper (filter cloth). The mesh size of the filter paper (filter cloth) is preferably such that the precipitated fine ceramic material does not pass through the filter paper (filter cloth). In addition, the first metal solution containing the precipitated fine ceramic material produced in step (I) can be solid-liquid separated, and the solid-liquid separation is not limited to filtration, and can be performed by any known method appropriately selected from decantation, centrifugation, etc. Filtration is more preferred.

[0099] Alternatively, instead of or in addition to the filtration in step (J), treatments such as crystallization and neutralization can be performed. The first metal solution obtained by the filtration can then be treated to separate and recover the first metal component, for example, as a first metal component compound (e.g., NiSO, NiCl, etc.). In the present invention, the separation and recovery of the first metal component includes not only the separation and recovery of the first metal component itself, but also the separation and recovery of the first metal component compound, which is a reaction product of a chemical reaction of the first metal component, as the first metal component.

[0100] (3) Effects and Effects According to the above separation and recovery method, it is possible to separate and recover the first metal component constituting the internal electrode layer 16, the second metal component constituting the external electrode 30, and the rare earth component contained in the ceramic layer 14 from post-sintering waste of multilayer ceramic capacitors. This will be explained in detail below.

[0101] The present inventors have considered the effective utilization of various components contained in waste after firing of multilayer ceramic capacitors (firing of fired electrode layers). In the post-firing waste, various components are in a sintered state due to the firing process. For example, the internal electrode layers are formed containing first metal particles (first metal sintered compacts) formed by firing a first metal powder such as Ni. Furthermore, for example, the ceramic layers are formed containing ceramic particles (ceramic sintered compacts) formed by firing a ceramic powder such as BaTiO. Furthermore, for example, the external electrodes are formed containing second metal particles (second metal sintered compacts) formed by firing a second metal powder such as Cu. The inventors have discovered that even when each part of a multilayer ceramic capacitor is in a sintered state, various components contained in the multilayer ceramic capacitor can be separated and recovered by devising a separation and recovery method.

[0102] Furthermore, by pulverizing the fired waste in step (B), it is possible to obtain a ceramic finely divided product, a rare earth-containing material, a first metal finely divided product, and a second metal finely divided product. Then, in step (C), the pulverized fired waste can be separated into a first separated product and a second separated product by separating the first separated product using a magnet. The first separated product includes the ceramic finely divided product and the first metal finely divided product. The second separated product includes the ceramic finely divided product, the rare earth-containing material, and the second metal finely divided product. Therefore, by separating and recovering the first separated product in step (C), it is possible to remove the second separated product from the fired waste, and to separate and recover the first separated product containing the first metal finely divided product as the first metal component.

[0103] Then, in step (D), the second separated material is dissolved in a non-oxidizing mineral acid to produce a rare earth component-containing solution in which the rare earth components in the rare earth powder-containing material are dissolved. This allows the rare earth component-containing solution to be separated and recovered as a rare earth component. At this time, the finely divided ceramic material and the finely divided second metal material are precipitated. The finely divided ceramic material reacts with the non-oxidizing mineral acid to become an undissolved material and precipitate. Furthermore, the finely divided second metal material, such as Cu, does not dissolve in the non-oxidizing mineral acid because it has a lower ionization tendency than the hydrogen ions contained in the non-oxidizing mineral acid.

[0104] Thereafter, the finely divided ceramic particles and the finely divided second metal particles in the second separated product extracted in step (D) are dissolved in ammonia water to produce a second metal solution in which the second metal components, such as Cu, in the finely divided second metal particles are dissolved. This allows the second metal solution to be separated and recovered as the second metal components. At this time, the finely divided ceramic particles in the second separated product do not dissolve in the ammonia water but remain precipitated.

[0105] By carrying out the separation and recovery method including steps (C), (D), and (E), rare earth components can be separated and recovered as a rare earth component-containing solution from the post-calcination waste after pulverization, and the second metal solution can be separated and recovered as a second metal component. Furthermore, as each step is carried out, the proportion of the rare earth component in the material containing the rare earth component and the proportion of the second metal component in the material containing the second metal component increase. Therefore, rare earth components such as Dy and second metal components such as Cu can be recovered at high quality.

[0106] The separation and recovery method of the above embodiment further includes step (I). In step (I), the first separated product is dissolved in a mineral acid to produce a first metal solution in which the first metal component contained in the first metal fine product is dissolved. In step (I), the ceramic fine product contained in the first separated product reacts with the mineral acid to become an undissolved substance and precipitate, so that the ceramic fine product and the first metal component contained in the first separated product are separated.

[0107] Therefore, by carrying out the separation and recovery method including steps (C) and (I), the first metal solution can be separated and recovered as the first metal component from the post-calcination waste after the fine particle size reduction. Furthermore, the proportion of the first metal component in the material containing the first metal component increases as each step is carried out. Therefore, the first metal component, such as Ni, can be recovered at a high quality.

[0108] As described above, the first metal component, the second metal component, the rare earth component, and the like are separated and recovered using post-sintering waste from multilayer ceramic capacitors. Therefore, the post-sintering waste can be used as a resource rather than being discarded as waste, thereby reducing the environmental load.

[0109] 2. Experimental Example Hereinafter, an experimental example will be described in which metal components and rare earth components were recovered from post-burning waste.

[0110] [Example] 10 g of fired waste was prepared. The 10 g of fired waste contained 35% by mass (3.5 g) of Ni, a first metal component, 7% by mass (0.7 g) of Cu, a second metal component, 54% by mass (5.4 g) of ceramic particles (ceramic sintered body) of BaTiO3, 2% by mass (0.2 g) of Dy, a rare earth component, and 2% by mass (0.2 g) of contaminants such as Mg, Mn, and SiO2 (step (A)). This fired waste was pulverized and refined (step (B)). The pulverized fired waste was mixed with 100 ml of water to prepare a slurry. This slurry was subjected to magnetic separation using a magnet. 4.5 g of a first separated product and 4.6 g of a second separated product were separated and recovered by this magnetic separation (step (C)). Then, 100 ml of water was added to 4.6 g of the second separated material, and 1 mol% sulfuric acid was added little by little to adjust the pH to 2. This precipitated the ceramic fine particles (BaTiO3) and the second metal fine particles (Cu) in the second separated material, and the Dy contained in the rare earth-containing material was dissolved in the sulfuric acid solution (step (D)). The solution in which the ceramic fine particles (BaTiO3) and the second metal fine particles (Cu) precipitated and the Dy dissolved in the sulfuric acid solution was filtered to obtain 90 ml of dysprosium sulfate (Dy2(SO4)3) solution (step (F)). 1 mol% caustic soda solution was added little by little to the 90 ml of dysprosium sulfate solution as an alkali, and the pH was adjusted to 8 (step (G)). This solution was filtered, and 0.1 g of Dy(OH)3 was separated and recovered. Therefore, by going through this process, approximately 40% of the Dy contained in the post-calcination waste was recovered.

[0111] In addition, 100 ml of water and 2 g of ammonium sulfate were added to 4.1 g of the filtered product of the ceramic fine powder (BaTiO3) and the second metal fine powder (Cu) recovered in step (F), and 1 mol% ammonia water was gradually added to adjust the pH to 9.5. This caused the ceramic fine powder (BaTiO3) to precipitate, and the second metal fine powder (Cu) was dissolved in ammonia water (step (E)). This solution was filtered, and 90 ml of [Cu(NH3)4] 2+Thus, by going through this process, approximately 60% of the Cu contained in the waste after calcination was recovered.

[0112] In addition, 100 ml of water was added to 4.5 g of the first separated material recovered in step (C), and 1 mol% sulfuric acid was added little by little to adjust the pH to 2. This precipitated the ceramic fine particles (BaTiO3) in the first separated material, and the first metal fine particles (Ni) were dissolved in the sulfuric acid solution (step (I)). The solution in which the ceramic fine particles (BaTiO3) precipitated and the first metal fine particles (Ni) were dissolved in the sulfuric acid solution was filtered to obtain 90 ml of nickel sulfate (Ni(SO4)) solution (step (J)). 1 mol% caustic soda solution was added little by little to the 90 ml of nickel sulfate solution as an alkali to adjust the pH to 10. This solution was filtered, and 4.4 g of Ni(OH)2 was separated and recovered. Therefore, by going through this process, approximately 80% of the Ni contained in the post-calcination waste was recovered.

[0113] [Experimental Results] From the above experiments, it has been found that the separation and recovery method according to the present embodiment uses post-sintering waste of multilayer ceramic capacitors as a starting material, and by undergoing processes such as magnetic separation and leaching by neutralization, it is possible to easily separate and refine high-quality rare earth components such as Dy, Ni, and Cu, a first metal component, and a second metal component.

[0114] Second Embodiment In the first embodiment described above, the external electrodes 30 include baked electrode layers 32. The baked electrode layers 32 are the outermost layers of the multilayer ceramic capacitor 10 (FIG. 3). However, the configuration of the external electrodes 30 is not limited to this. In the second embodiment, the external electrodes 30 include baked electrode layers 32 and plated layers. The plated layers are the outermost layers of the multilayer ceramic capacitor. Descriptions of the same content as in the first embodiment will be omitted or simplified.

[0115] Fig. 7 is a cross-sectional view (1) parallel to a plane including the length direction and stacking direction of a multilayer ceramic capacitor according to a second embodiment of the present invention, and Fig. 8 is a cross-sectional view (2) parallel to a plane including the length direction and stacking direction of another multilayer ceramic capacitor according to the second embodiment of the present invention.

[0116] Multilayer ceramic capacitors 10A (FIG. 7) and 10B (FIG. 8) according to the second embodiment include a laminate 12 similar to that of the first embodiment, and further include an external electrode 30 disposed on the laminate 12. The external electrode 30 includes a baked electrode layer 32 and a plating layer 34 disposed on the baked electrode layer 32. The plating layer 34 is the outermost layer of the multilayer ceramic capacitors 10A and 10B. The configuration other than the plating layer 34 is the same as that of the first embodiment. The plating layer 34 is formed, for example, containing at least one selected from Ni, Sn, Cu, Ag, etc. Note that the multilayer ceramic capacitor 10 according to the first embodiment does not include a plating layer (FIG. 3).

[0117] The multilayer ceramic capacitors 10A and 10B according to the second embodiment are formed by performing the steps 1 to 7 of the first embodiment described above, followed by a step (step 8) of disposing a plating layer 34 on the baked electrode layer 32. In step 8, a plating process is performed to form a first plating layer 34a (first lower-layer plating layer 34a1, first upper-layer plating layer 34a2) on the first baked electrode layer 32a, and a second plating layer 34b (second lower-layer plating layer 34b1, second upper-layer plating layer 34b2) on the second baked electrode layer 32b. The plating layer 34 is formed, for example, by barrel plating. Either electrolytic plating or electroless plating may be used for the plating process. However, electroless plating has the disadvantage of requiring pretreatment using a catalyst or the like to improve plating deposition speed, which complicates the process. Therefore, electrolytic plating is usually preferred.

[0118] The multilayer ceramic capacitors 10A, 10B having the plating layer 34 according to the second embodiment are also included in the post-sintering (sintering for fired electrode layers) waste, similar to the multilayer ceramic capacitor 10 according to the first embodiment (sometimes referred to as the multilayer ceramic capacitor 10 without the plating layer 34). Depending on the material constituting the plating layer 34, the multilayer ceramic capacitors 10A, 10B having the plating layer 34 may be introduced into the separation and recovery method shown in Fig. 1 described above, or into the separation and recovery method shown in Fig. 9 described below. The separation and recovery method shown in Fig. 1 does not include a step of removing the plating layer 34, but the separation and recovery method shown in Fig. 9 includes a step of removing the plating layer 34 (step (K)).

[0119] The plating layer 34 may be formed from a single plating layer (FIG. 7) or may be formed by laminating multiple plating layers (FIG. 8). Below, a multilayer ceramic capacitor 10A in which the plating layer 34 is a single plating layer and a multilayer ceramic capacitor 10B in which the plating layer 34 is a multiple plating layer will be described. In addition, a method for separating and recovering rare earth components and metal components from post-sintering waste will be described for each of the multilayer ceramic capacitors 10A and 10B.

[0120] 1. Multilayer Ceramic Capacitor Including a Single Plating Layer (1) Configuration In the multilayer ceramic capacitor 10A shown in FIG. 7, the external electrode 30 includes a baked electrode layer 32 and a plating layer 34 disposed on the baked electrode layer 32. The plating layer 34 is formed of a single plating layer. In the example shown in FIG. 7, the plating layer 34 includes a first lower-layer plating layer (first first-stage plating layer) 34a1 and a second lower-layer plating layer 34b1 (second first-stage plating layer). The first external electrode 30a includes a first baked electrode layer 32a and a first lower-layer plating layer 34a1 on the first baked electrode layer 32a. The second external electrode 30b includes a second baked electrode layer 32b and a second lower-layer plating layer 34b1 on the second baked electrode layer 32b. The first and second lower plating layers 34a1, 34b1 are the outermost layers of the layers disposed on the laminate 12. The baked electrode layer 32 serves as a base for the plating layer 34, and is therefore sometimes referred to as a base electrode layer.

[0121] (2) Separation and Recovery Method (2-1) Overview of Separation and Recovery Method As in the first embodiment, the multilayer ceramic capacitor 10A having the plating layer 34 is included in the post-sintering waste (sintering for the fired electrode layer). Therefore, the multilayer ceramic capacitor 10A having the plating layer 34 can be input into the separation and recovery method of FIG. 1 described in the first embodiment. That is, in the preparation of the post-sintering waste in step (A), the multilayer ceramic capacitor 10A having the plating layer 34 can be prepared as the post-sintering waste. Thereafter, by going through the separation and recovery method described in FIG. 1, the first metal component, the second metal component, and the rare earth component can be separated and recovered from the multilayer ceramic capacitor 10A having the plating layer 34.

[0122] However, it is also possible to recover the first metal component, the second metal component, and the rare earth component from the multilayer ceramic capacitor 10A after removing the plating layer 34 from the multilayer ceramic capacitor 10A. Figure 9 is a flow diagram showing a method for separating and recovering rare earth components and metal components from post-fired multilayer ceramic capacitor waste (firing for fired electrode layers), including a plating removal step. The separation and recovery method of Figure 9 differs from the separation and recovery method of Figure 1 in that it includes a plating removal step (K) for removing the plating layer 34 between the post-fired waste preparation step (A) and the pulverization step (B). The separation and recovery method of Figure 9 is the same as the separation and recovery method of Figure 1, except for the inclusion of step (K).

[0123] In the separation and recovery of various components from the multilayer ceramic capacitor 10A having the plating layer 34, whether to use the separation and recovery method of FIG. 1 which does not include a plating removal step or the separation and recovery method of FIG. 9 which includes a plating removal step can be divided, for example, as follows:

[0124] (2-2) When a separation and recovery method (FIG. 1) not including a plating removal step is used In a multilayer ceramic capacitor 10A having a plating layer 34, the metal component contained in both the first and second lower plating layers 34a1, 34b1 is the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 1 and is further processed in each step from step (B) onward of the separation and recovery method shown in FIG. 1. For example, when the first metal component is contained in both the first and second lower plating layers 34a1, 34b1, the first metal component of the plating layer 34 can be separated and recovered together with the first metal component contained in the internal electrode layer 16. Furthermore, for example, when the second metal component is contained in both the first and second lower plating layers 34a1, 34b1, the second metal component of the plating layer 34 can be separated and recovered together with the second metal component contained in the baked electrode layer 32. It is also possible to separate and recover rare earth components from the ceramic layer 14.

[0125] A more specific example will be described. For example, assume that both the first and second lower plating layers 34a1, 34b1 are plating layers primarily composed of Ni. Furthermore, assume that the internal electrode layer 16 contains Ni as the first metal component. In this case, the multilayer ceramic capacitor 10A is prepared as post-sintering waste in step (A) of FIG. 1 without removing the first and second lower plating layers 34a1, 34b1. Thereafter, by undergoing each step from step (B) onward in the separation and recovery method of FIG. 1, the first metal component, Ni, can be separated and recovered from the first and second lower plating layers 34a1, 34b1 and the internal electrode layer 16. Note that the second metal component can be separated and recovered from the fired electrode layer 32, and the rare earth component can be separated and recovered from the ceramic layer 14.

[0126] As another example, assume that both the first and second lower plating layers 34a1, 34b1 are plating layers primarily composed of Cu. Furthermore, assume that the baked electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10A is prepared as post-sintering waste in step (A) of FIG. 1 without removing the first and second lower plating layers 34a1, 34b1. Thereafter, by undergoing step (B) and subsequent steps of the separation and recovery method of FIG. 1, the second metal component, Cu, can be separated and recovered from the first and second lower plating layers 34a1, 34b1 and the baked electrode layer 32. The first metal component can be separated and recovered from the internal electrode layer 16, and the rare earth component can be separated and recovered from the ceramic layer 14.

[0127] (2-3) Separation and Recovery Method Including a Plating Removal Step (FIG. 9) In a multilayer ceramic capacitor 10A having a plating layer 34, the metal components contained in both the first and second lower plating layers 34a1, 34b1 are different from both the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32. In other words, the metal component (third metal component) contained in the first and second lower plating layers 34a1, 34b1 is different from both the first metal component and the second metal component. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9. Then, the first and second lower plating layers 34a1, 34b1 are removed by plating removal in step (K). Thereafter, the multilayer ceramic capacitor 10A from which the plating layer 34 has been removed is further processed in step (B) and subsequent steps of the separation and recovery method shown in FIG. 9. This allows the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14 to be separated and recovered from the multilayer ceramic capacitor 10A from which the plating layer 34 has been removed.

[0128] A more specific example will be described. For example, suppose both the first and second lower plating layers 34a1, 34b1 are plating layers primarily composed of Sn (an example of a third metal component). Furthermore, suppose the internal electrode layer 16 contains Ni as the first metal component, and the fired electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9 . Then, in step (K) of FIG. 9 , the first and second lower plating layers 34a1, 34b1 primarily composed of Sn are removed. The first and second lower plating layers 34a1, 34b1 primarily composed of Sn can be removed by immersing the multilayer ceramic capacitor 10A having the plating layer 34 in an alkaline solution other than ammonia water, such as sodium hydroxide or potassium hydroxide. In this case, the fired electrode layer 32 primarily composed of Cu is exposed to the alkaline solution after the plating layer 34 is removed. However, the baked electrode layer 32, which is mainly composed of Cu, is not easily corroded by the alkaline solution. Here, the alkaline solution other than ammonia water is adjusted to, for example, a pH of about 12. Thereafter, by going through each step from step (B) of the separation and recovery method in Figure 9 onwards, it is possible to separate and recover the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14.

[0129] In the above example, the Sn-based plating layer 34 is removed using an alkaline solution other than ammonia water. However, the Sn-based plating layer 34 can also be removed using an acidic solution with no oxidizing power, such as hydrochloric acid or dilute sulfuric acid. In this case, the Cu-based baked electrode layer 32 is exposed to the acidic solution when the plating layer 34 is removed. However, the Cu-based baked electrode layer 32 is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to, for example, a pH of approximately 2.

[0130] Note that even when the metal components contained in both the first and second lower plating layers 34a1, 34b1 are the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32, the multilayer ceramic capacitor 10A having the plating layer 34 may be prepared as waste after firing in step (A) of Fig. 9. Then, the first and second lower plating layers 34a1, 34b1 may be removed by plating removal in step (K).

[0131] For example, suppose both the first and second lower plating layers 34a1, 34b1 are Ni-based. Furthermore, suppose the internal electrode layer 16 contains Ni as the first metal component, and the baked electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9 . Then, in step (K) of FIG. 9 , the Ni-based first and second lower plating layers 34a1, 34b1 are removed. The Ni-based first and second lower plating layers 34a1, 34b1 can be removed by immersing the multilayer ceramic capacitor 10A having the plating layer 34 in a non-oxidizing acidic solution, such as hydrochloric acid or dilute sulfuric acid. In this case, the Cu-based baked electrode layer 32 is exposed to the acidic solution after the plating layer 34 is removed. However, the baked electrode layer 32, which is primarily composed of Cu, is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to, for example, a pH of about 2. Thereafter, by going through each step from step (B) of the separation and recovery method in Figure 9 onwards, it is possible to separate and recover the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14.

[0132] 2. Multilayer Ceramic Capacitor Including Multiple Plating Layers (1) Configuration In a multilayer ceramic capacitor 10B shown in FIG. 8 , the external electrode 30 includes a baked electrode layer 32 and a plating layer 34 disposed on the baked electrode layer 32. The plating layer 34 is formed from multiple plating layers. In the example of FIG. 8 , the plating layer 34 is formed from two plating layers. Specifically, the plating layer 34 includes a first lower-layer plating layer (first first-stage plating layer) 34a1 and a second lower-layer plating layer (second first-stage plating layer) 34b1, as well as a first upper-layer plating layer (first second-stage plating layer) 34a2 and a second upper-layer plating layer (second second-stage plating layer) 34b2. The first external electrode 30a includes a first baked electrode layer 32a, a first lower-layer plating layer 34a on the first baked electrode layer 32a, and a first upper-layer plating layer 34a on the first lower-layer plating layer 34a. The second external electrode 30b includes a second baked electrode layer 32b, a second lower-layer plating layer 34b on the second baked electrode layer 32b, and a second upper-layer plating layer 34b on the second lower-layer plating layer 34b. The first upper-layer plating layer 34a and the second upper-layer plating layer 34b are the outermost layers arranged on the laminate 12.

[0133] The multilayer ceramic capacitor 10B having the plating layer 34 is formed by carrying out the steps (Step 1) to (Step 7) of the first embodiment described above, followed by a step (Step 8) of disposing the plating layer 34 on the baked electrode layer 32. In (Step 8), a plating process is carried out to sequentially form a first lower-layer plating layer 34a1 and a first upper-layer plating layer 34a2 on the first baked electrode layer 32a, and a second upper-layer plating layer 34b2 on the second lower-layer plating layer 34b1 on the second baked electrode layer 32b.

[0134] (2) Separation and Recovery Method (2-1) Overview of Separation and Recovery Method As in the first embodiment, the multilayer ceramic capacitor 10B having the plating layer 34 is included in the post-sintering waste (sintering for the fired electrode layer). Therefore, the multilayer ceramic capacitor 10B having the plating layer 34 can be input into the separation and recovery method of FIG. 1 described in the first embodiment. That is, in the preparation of the post-sintering waste in step (A), the multilayer ceramic capacitor 10B having the plating layer 34 can be prepared as the post-sintering waste. Thereafter, by going through the separation and recovery method described in FIG. 1, the first metal component, the second metal component, and the rare earth component can be separated and recovered from the multilayer ceramic capacitor 10B having the plating layer 34.

[0135] However, it is also possible to remove the plating layer 34 from the multilayer ceramic capacitor 10B having the plating layer 34, and then recover the first metal component, the second metal component, and the rare earth component from the multilayer ceramic capacitor 10B.

[0136] In the separation and recovery of various components from the multilayer ceramic capacitor 10B having the plating layer 34, whether to use the separation and recovery method of FIG. 1 which does not include a plating removal step or the separation and recovery method of FIG. 9 which includes a plating removal step can be divided, for example, as follows:

[0137] (2-2) When a Separation and Recovery Method (FIG. 1) Not Including a Plating Removal Step is Used In a multilayer ceramic capacitor 10B having a plating layer 34, the metal components contained in the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 are the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the baked electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as waste after firing in step (A) of FIG. 1 and treated by the separation and recovery method shown in FIG. 1. For example, the metal components of the first and second lower plating layers 34a1, 34b1 may be the same as the first metal component contained in the internal electrode layer 16. Furthermore, the metal components of the first and second upper plating layers 34a2, 34b2 may be the same as the second metal component contained in the baked electrode layer 32. Alternatively, for example, the metal components of the first and second lower plating layers 34a1, 34b1 may be the same as the second metal component contained in the baked electrode layer 32. Furthermore, the metal components of the first and second upper plating layers 34a2, 34b2 may be the same as the first metal component contained in the internal electrode layer 16. In this case, the first and second metal components of the plating layer 34 can be separated and recovered together with the first metal component contained in the internal electrode layer 16 and the second metal component contained in the baked electrode layer 32. Note that rare earth components can be separated and recovered from the ceramic layer 14.

[0138] A further specific example will be given. For example, suppose the first and second lower plating layers 34a1, 34b1 are plating layers primarily composed of Ni (or Cu). Furthermore, suppose the first and second upper plating layers 34a2, 34b2 are plating layers primarily composed of Cu (or Ni). Furthermore, suppose the internal electrode layer 16 contains Ni as a first metal component. Furthermore, suppose the baked electrode layer 32 contains Cu as a second metal component. In this case, the multilayer ceramic capacitor 10B is prepared as post-firing waste in step (A) of FIG. 1 without the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 being removed. 1 , by going through each step from step (B) onwards, it is possible to separate and recover Ni, which is the first metal component, and Cu, which is the second metal component, from the first and second lower plating layers 34a1, 34b1, the first and second upper plating layers 34a2, 34b2, the internal electrode layer 16, and the baked electrode layer 32. It is also possible to separate and recover rare earth components from the ceramic layer 14.

[0139] (2-3) Separation and Recovery Method Including Plating Removal Step (FIG. 9) As an example, in a multilayer ceramic capacitor 10B having a plating layer 34, the metal component (third metal component) contained in the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 is different from both the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9. Then, the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 are removed by plating removal in step (K). Thereafter, the multilayer ceramic capacitor 10B from which the plating layer 34 has been removed is further processed in step (B) and subsequent steps of the separation and recovery method shown in FIG. 9. This allows the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14 to be separated and recovered from the multilayer ceramic capacitor 10B from which the plating layer 34 has been removed.

[0140] As another example, in a multilayer ceramic capacitor 10B having a plating layer 34, the (third metal component) contained in the first and second upper plating layers 34a, 34b is different from both the first metal component contained in the internal electrode layer 16 and the second metal component contained in the baked electrode layer 32. Meanwhile, the metal components contained in the first and second lower plating layers 34a, 34b are the same as either the first metal component contained in the internal electrode layer 16 or the second metal component contained in the baked electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9 . Then, the first and second upper plating layers 34a, 34b are removed by plating removal in step (K). The multilayer ceramic capacitor 10B from which the first and second upper plating layers 34a, 34b have been removed is then further processed in step (B) and subsequent steps of the separation and recovery method shown in FIG. 9 . As a result, from the multilayer ceramic capacitor 10B from which the first and second upper plating layers 34a2, 34b2 have been removed, it is possible to separate and recover the metal components (first metal component or second metal component) contained in the first and second lower plating layers 34a1, 34b1, the first metal component constituting the internal electrode layer 16, the second metal component constituting the fired electrode layer 32, and the rare earth component contained in the ceramic layer 14.

[0141] The above-mentioned other example will be further described with a specific example. For example, suppose the metal component contained in the first and second upper plating layers 34a2, 34b2 is a plating layer containing Sn (an example of a third metal component) as the main component. Also, suppose the metal component contained in the first and second lower plating layers 34a1, 34b1 is a plating layer containing Ni (or Cu) as the main component. Furthermore, suppose the internal electrode layer 16 contains Ni as the first metal component, and the fired electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as waste after firing in step (A) of FIG. 9 . Then, in step (K) of FIG. 9 , the first and second upper plating layers 34a2, 34b2 containing Sn as the main component are removed. The first and second upper plating layers 34a, 34b, primarily composed of Sn, can be removed by immersing the multilayer ceramic capacitor 10B having the plating layers 34 in an alkaline solution other than aqueous ammonia, such as sodium hydroxide or potassium hydroxide. In this case, the first and second lower plating layers 34a, 34b, primarily composed of Ni (or Cu), are exposed to the alkaline solution as the first and second upper plating layers 34a, 34b are removed. However, the first and second lower plating layers 34a, 34b, primarily composed of Ni (or Cu), are not easily corroded by the alkaline solution. Furthermore, the baked electrode layer 32, primarily composed of Cu, is also not easily corroded by the alkaline solution. The alkaline solution other than aqueous ammonia is adjusted to, for example, a pH of approximately 12. 9 , the first metal component Ni and the second metal component Cu can be separated and recovered from the first and second lower plating layers 34a1, 34b1, the internal electrode layer 16, and the baked electrode layer 32. Rare earth components can also be separated and recovered from the ceramic layer 14.

[0142] In the above example, only the first and second upper plating layers 34a, 34b are removed in step (K). However, both the first and second upper plating layers 34a, 34b and the first and second lower plating layers 34a, 34b may be removed. For example, suppose the metal component contained in the first and second upper plating layers 34a, 34b is primarily Sn (an example of a third metal component). Also, suppose the metal component contained in the first and second lower plating layers 34a, 34b is primarily Ni rather than Cu. Furthermore, suppose the internal electrode layer 16 contains Ni as the first metal component, and the fired electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9 . Then, in step (K) of FIG. 9 , the first and second upper plating layers 34a2, 34b2, primarily composed of Sn, and the first and second lower plating layers 34a1, 34b1, primarily composed of Ni, are removed. The first and second upper plating layers 34a2, 34b2, primarily composed of Sn, and the first and second lower plating layers 34a1, 34b1, primarily composed of Ni, can be removed by immersing the multilayer ceramic capacitor 10B having the plating layers 34 in a non-oxidizing acidic solution, such as hydrochloric acid or dilute sulfuric acid. In this case, the baked electrode layer 32, primarily composed of Cu, is exposed to the acidic solution as the plating layers 34 are removed. However, the baked electrode layer 32, primarily composed of Cu, is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to, for example, a pH of approximately 2. 9 , the first metal component Ni and the second metal component Cu can be separated and recovered from the internal electrode layer 16 and the fired electrode layer 32. The rare earth component can be separated and recovered from the ceramic layer 14.

[0143] In the above process, the first and second upper plating layers 34a, 34b, each primarily composed of Sn, and the first and second lower plating layers 34a, 34b, each primarily composed of Ni, are simultaneously removed using a non-oxidizing acidic solution. However, they may also be removed sequentially. First, the multilayer ceramic capacitor 10B is immersed in an alkaline solution (e.g., about pH 12) other than aqueous ammonia, such as sodium hydroxide or potassium hydroxide, to remove the first and second upper plating layers 34a, 34b. Then, the multilayer ceramic capacitor 10B is immersed in a non-oxidizing acidic solution (e.g., about pH 2), such as hydrochloric acid or dilute sulfuric acid, to remove the first and second lower plating layers 34a, 34b, each primarily composed of Ni. 9 , the first metal component Ni and the second metal component Cu can be separated and recovered from the internal electrode layer 16 and the fired electrode layer 32. The rare earth component can be separated and recovered from the ceramic layer 14.

[0144] 1 or 9 can be used to separate and recover the first metal component constituting the internal electrode layer 16, the second metal component constituting the external electrode 30, and the rare earth component contained in the ceramic layer 14 from the multilayer ceramic capacitors 10A, 10B according to the second embodiment having the plating layer 34, as in the first embodiment. Furthermore, by employing a separation and recovery method suitable for separating and recovering the metal components from the plating layer 34, it may also be possible to recover the first metal component and the second metal component from the plating layer 34.

[0145] As described above, although the embodiments of the present invention have been disclosed in the above description, the present invention is not limited thereto. In other words, various modifications can be made to the above-described embodiments in terms of mechanism, shape, material, quantity, position, arrangement, etc., without departing from the scope of the technical idea and purpose of the present invention, and such modifications are included in the present invention.

[0146] <Other Modifications>

[0147] (1) Generation of Slurry Using an Aqueous Solvent in Step (B) In the first and second embodiments described above, the post-calcination waste is pulverized and refined in step (B). However, as long as the post-calcination waste can be refined, the post-calcination waste may be dispersed in a solvent (e.g., a solvent such as an aqueous solvent) to form a slurry, in addition to or instead of the refinement in step (B) (particularly, refinement by pulverization), and refined. Here, the refinement in which the post-calcination waste is mixed with a solvent to form a slurry is called wet refinement. Furthermore, among wet refinement, the refinement in which the post-calcination waste is pulverized in a slurry formed by mixing the post-calcination waste with a solvent is called wet grinding. Note that, for example, water can be used as the aqueous solvent.

[0148] Furthermore, in the first and second embodiments described above, during magnetic separation in step (C), the calcined waste after being pulverized in step (B) can be mixed with and dispersed in an aqueous solvent such as water to form a slurry. However, as described above, when the calcined waste is pulverized using an aqueous solvent in addition to or instead of pulverization in step (B), the slurried calcined waste may be magnetically separated in step (C). In other words, the effort of generating a slurry in the magnetic separation in step (C) can be omitted.

[0149] It is also possible to prepare a slurry of the post-calcination waste using an organic solvent. However, when the post-calcination waste is prepared in a slurry form using an organic solvent, a step of removing the organic solvent is required in the separation and recovery method. Therefore, it is preferable to prepare a slurry of the post-calcination waste using an aqueous solvent such as water.

[0150] (2) Other Examples of Post-Firing Waste In the first and second embodiments described above, the post-firing waste refers to waste that has undergone the firing for the fired electrode layers in (Step 7). However, the post-firing waste is not limited to this. The post-firing waste may also include waste that has not yet undergone the firing for the fired electrode layers and that has been fired before being input into the separation and recovery methods of FIGS. 1 and 9. In this case, the firing is preferably carried out at the firing temperature used in the firing for the fired electrode layers.

[0151] Examples of waste before firing for the fired electrode layers include waste discharged in (Step 1) to (Step 6). Furthermore, waste before firing for the fired electrode layers may include waste after the paste for the fired electrode layers has been applied to the laminate 12 in (Step 7) but before firing for the fired electrode layers has been performed. Specifically, examples of waste before firing for the fired electrode layers include waste of dielectric slurry and conductive paste for the internal electrode layers in (Step 1), waste of dielectric sheets on which the patterns of the internal electrode layers have been formed and dielectric sheets on which the patterns of the internal electrode layers are not printed in (Step 2), excess laminate blocks such as scraps of laminate blocks discharged after cutting the laminate blocks in (Step 4), and defective laminate chips after cutting, waste after degreasing in (Step 5), and waste after firing of the laminate chips in (Step 6).

[0152] (3) Other Multilayer Ceramic Capacitors for Which Post-Firing Waste is Discharged In the above first and second embodiments, a two-terminal multilayer ceramic capacitor having two terminals, a first external electrode 30a and a second external electrode 30b, has been described as the multilayer ceramic capacitor to be manufactured. However, the scope of application of the present invention is not limited to post-firing waste from two-terminal multilayer ceramic capacitors. The present invention is applicable to post-firing waste from multilayer ceramic capacitors having internal electrode layers containing a first metal component such as Ni, external electrodes containing a second metal component such as Cu, and ceramic layers containing a dielectric material such as BaTiO3 and a rare earth component as an additive such as Dy. Therefore, the present invention may also be applied to post-firing waste from three-terminal multilayer ceramic capacitors, for example.

[0153] For example, a three-terminal multilayer ceramic capacitor includes a laminate 12 similar to those in the first and second embodiments and first to fourth external electrodes. The internal electrode layers 16 include a first internal electrode layer extending to the first end face 12e and the second end face 12f, and a second internal electrode layer extending to the first side face 12c and the second side face 12d. A first external electrode is disposed on the first end face 12e of the laminate 12. The first external electrode is electrically connected to the first internal electrode layer exposed at the first end face 12e of the laminate 12. A second external electrode is disposed on the second end face 12f of the laminate 12. The second external electrode is electrically connected to the first internal electrode layer exposed at the second end face 12f of the laminate 12. A third external electrode is disposed on the first side face 12c of the laminate 12. The third external electrode is electrically connected to the second internal electrode layer exposed at the first side surface 12c of the laminate 12. A fourth external electrode is disposed on the second side surface 12d of the laminate 12. The fourth external electrode is electrically connected to the second internal electrode layer exposed at the second side surface 12d of the laminate 12. The first to fourth external electrodes may include only baked electrode layers, or may include baked electrode layers and plated layers.

[0154] (4) Regarding the filtration in step (F): When the second separated material is dissolved in a non-oxidizing mineral acid in step (D), the ceramic fine particles contained in the second separated material react with the non-oxidizing mineral acid to form undissolved particles and precipitate. Furthermore, the second metal fine particles, such as Cu, have a lower ionization tendency than the hydrogen ions contained in the non-oxidizing mineral acid and therefore do not dissolve in the non-oxidizing mineral acid. Meanwhile, the rare earth components in the rare earth-containing material dissolve to produce a rare earth component-containing solution. The rare earth component-containing solution containing the undissolved particles can also be recovered as the rare earth components. In this case, the solid-liquid separation step (F), such as filtration, can be omitted.

[0155] (5) Omission of Neutralization in Step (G) In the first and second embodiments described above, the rare earth components can be separated and recovered as a rare earth component-containing solution in the dissolution of the second separated product in Step (D), so the neutralization in Step (G) can be omitted.

[0156] (6) Omission of Various Treatments in Steps (I) and (J) In the first and second embodiments described above, in the magnetic separation in step (C), the first separated material containing the first metal microparticles can be separated and recovered as the first metal component. Therefore, steps (I) and (J) can be omitted. Furthermore, in the dissolution of the first separated material in step (I), the first metal solution can be separated and recovered as the first metal component. Therefore, the filtration in step (J) can be omitted.

[0157] (7) Other methods for separating and recovering rare earth components In the first and second embodiments described above, rare earth component compounds such as Dy(OH) are separated and recovered as rare earth components in the neutralization step (G). However, the method for separating and recovering rare earth components is not limited to this. For example, the rare earth components can be recovered as follows.

[0158] (a) The rare earth component compound obtained by the neutralization in step (G) is heat-treated to produce an oxide, which can be recovered as a rare earth component. For example, if the rare earth component compound obtained after the neutralization in step (G) is Dy(OH), dysprosium oxide (DyO) can be recovered as a rare earth component by heat-treating Dy(OH).

[0159] (b) The rare earth component compound obtained by the neutralization in step (G) is dissolved in hydrochloric acid to produce a chloride, which can be recovered as a rare earth component. For example, if the rare earth component compound obtained after the neutralization in step (G) is Dy(OH), a dysprosium chloride (DyCl) solution is produced by dissolving Dy(OH) in hydrochloric acid. The dysprosium chloride solution is distilled off to evaporate the solvent, and dysprosium chloride hexahydrate (DyCl.6H0) can be recovered as a rare earth component.

[0160] (c) As in (b) above, a dysprosium chloride solution is produced by dissolving Dy(OH)3, the rare earth component compound obtained after neutralization in step (G), in hydrochloric acid. This can then be further purified to recover a high-purity rare earth component. For example, the dysprosium chloride solution produced as described above can be purified by solvent extraction, and a high-purity dysprosium chloride solution can be recovered as a rare earth component. Solvent extraction is a separation and purification method that utilizes solute partitioning, in which a solute dissolved in one of the immiscible liquids, an oil phase and an aqueous phase, is transferred to the other. Methods other than solvent extraction, such as an ion exchange resin method, can also be used.

[0161] (d) High-purity dysprosium oxide (DyO) can also be recovered from the high-purity dysprosium chloride solution obtained by the solvent extraction described in (c) above. In this case, for example, oxalic acid is first added to the high-purity dysprosium chloride solution to precipitate dysprosium oxalate. This is then filtered to recover high-purity dysprosium oxalate hexahydrate (Dy(C0)6H0). By heat-treating this high-purity dysprosium oxalate hexahydrate, high-purity dysprosium oxide (DyO) can be recovered as a rare earth component.

[0162] (e) High-purity dysprosium chloride hexahydrate can also be recovered from the high-purity dysprosium chloride solution obtained by the solvent extraction described in (c) above. In this case, for example, high-purity dysprosium chloride hexahydrate is recovered by distilling off the high-purity dysprosium chloride solution and evaporating the solvent.

[0163] (f) State of Rare Earth Component The recovered rare earth component may be in a liquid state, a solid state, or a mixture of liquid and solid. The crystal lattice of the rare earth component may be in an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

[0164] (8) Other methods for separating and recovering the first metal component In the first and second embodiments described above, the first metal fine particles are dissolved in a mineral acid in the dissolution of the first separated product in step (I). The first metal solution is then separated and recovered as the first metal component. Furthermore, in the subsequent filtration step (J), the first metal solution containing the precipitated ceramic fine particles is filtered, and the first metal solution from which the ceramic fine particles have been removed is separated and recovered as the first metal component. However, the separation and recovery of the first metal component is not limited to this. For example, the first metal component can be recovered as follows.

[0165] (a) The first metal component compound can be recovered as the first metal component by crystallizing the first metal solution. For example, if the first metal solution obtained after dissolving the first finely divided metal in step (I) is a nickel sulfate (NiSO4) solution, nickel sulfate hexahydrate (NiSO4.6H2O) can be recovered as the first metal component by crystallizing and filtering the nickel sulfate solution.

[0166] (b) A high-purity first metal component can be recovered by purifying the first metal solution obtained after dissolving the first finely divided metal product in step (I). For example, a nickel sulfate (NiSO4) solution, which is the first metal solution, can be purified by an ion exchange resin method, a solvent extraction method, or the like, and a high-purity nickel sulfate solution can be recovered as the first metal component.

[0167] (c) The high-purity nickel sulfate solution recovered in (b) above is crystallized and filtered to recover nickel sulfate hexahydrate (NiSO4.6H2O) as the first metal component.

[0168] (d) A high-purity first metal component can be recovered by purifying the first metal solution obtained after dissolving the first metal fine particles in step (I) by a method different from the above-mentioned (b). For example, high-purity solid Ni can be precipitated from a nickel sulfate solution, which is the first metal solution, by a method of precipitating a solid dissolved in the solution, such as electrolytic deposition, and recovered as the first metal component.

[0169] (e) By processing the high-purity Ni recovered in (d) above, nickel chloride hexahydrate (NiCl.6H0) can be recovered as the first metal component. For example, by dissolving the high-purity Ni recovered in (d) above in hydrochloric acid, a high-purity nickel chloride (NiCl) solution is produced. By spray-drying the nickel chloride solution, high-purity nickel chloride hexahydrate is produced. By further drying the high-purity nickel chloride hexahydrate with hot air, even higher-purity nickel chloride hexahydrate can be recovered as the first metal component.

[0170] (f) The first metal solution obtained after dissolving the first finely divided metal in step (I) can be neutralized to produce chlorides, which can then be recovered as the first metal component. For example, the first metal solution, a nickel sulfate solution, is neutralized by adjusting the pH to, for example, about pH 10 (pH 9 or higher and pH 11 or lower) with an alkali such as sodium hydroxide or potassium hydroxide, thereby precipitating nickel hydroxide (Ni(OH)). The precipitated nickel hydroxide (Ni(OH)) can be separated and recovered, for example, by filtration. Furthermore, nickel hydroxide is dissolved in hydrochloric acid to produce a nickel chloride (NiCl) solution. Next, nickel chloride hexahydrate (NiCl.6H0) can be recovered as the first metal component by distilling off the nickel chloride solution and evaporating the solvent.

[0171] (g) State of the First Metal Component The recovered metal component may be in a liquid state, a solid state, or a mixture of liquid and solid. The crystal lattice of the metal component may be in an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

[0172] (9) Other Manufacturing Processes for Multilayer Ceramic Capacitors In the first and second embodiments described above, the manufacturing method for the multilayer ceramic capacitor 10 includes, in order, forming a laminate block (step 3), cutting into laminated chips (step 4), degreasing (step 5), firing the laminated chips (step 6), and applying and firing a baking electrode layer paste (step 7). However, the manufacturing method for the multilayer ceramic capacitor 10 is not limited to this. For example, before the degreasing (step 5) and before the firing (firing of the laminated chips) (step 6), a baking electrode layer paste may be applied to the unfired laminated chips, followed by degreasing and firing of the baking electrode layers. That is, first, a baking electrode layer paste containing Ni, glass components, resin components, etc. is applied to the laminated chips before degreasing (step 5). Next, the laminated chips coated with the baking electrode layer paste are degreased, and then the baking electrode layers are fired. The temperature during degreasing is preferably, for example, higher than 800°C and lower than 1000°C. The firing temperature for the fired electrode layers is preferably, for example, higher than 1000° C. and not higher than 1400° C. These steps are performed after cutting into laminated chips in step 4 of the above-mentioned manufacturing method and before the plating step in step 8. In these steps, the firing of the laminated chips in step 6 and the firing of the paste for the fired electrode layers in step 7 are performed in a single firing.

[0173] <1> (A) a step of preparing fired waste of a multilayer ceramic capacitor, the fired waste comprising a laminate including ceramic layers and internal electrode layers, and fired electrode layers disposed on the laminate as outermost layers and connected to the internal electrode layers, the ceramic layers having aggregates of a plurality of ceramic particles, a rare earth-containing material containing a rare earth component being present at grain boundaries between the plurality of ceramic particles, the internal electrode layers containing a first metal component which is a magnetic base metal, the fired electrode layers containing a second metal component which is a non-magnetic noble metal, and the ceramic layers, the internal electrode layers, and the fired electrode layers being sintered; (B) a step of micronizing the fired waste to obtain a ceramic micronized material obtained by micronizing the ceramic layers, the rare earth-containing material, a first metal micronized material obtained by micronizing the internal electrode layers, and a second metal micronized material obtained by micronizing the fired electrode layers; (C) using a magnet to separate and recover the fired waste after the step (B) into a first separated product containing the ceramic finely divided product and the first metal finely divided product, and a second separated product containing the ceramic finely divided product, the rare earth-containing material, and the second metal finely divided product; (D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic finely divided product and the second metal finely divided product in the second separated product and producing a rare earth component-containing solution in which the rare earth component in the rare earth-containing material is dissolved; (E) dissolving the ceramic finely divided product and the second metal finely divided product in the second separated product precipitated in the step (D) in ammonia water, thereby precipitating the ceramic finely divided product in the second separated product and producing a second metal solution in which the second metal component contained in the second metal finely divided product is dissolved; The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors comprises:

[0174] <2> (I) The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to <1>, further comprising the step of dissolving the first separated product after the step (C) in at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, thereby precipitating the ceramic fine particles in the first separated product and producing a first metal solution in which the first metal component contained in the first metal fine particles in the first separated product is dissolved.

[0175] <3> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to <1> or <2>, wherein in the step (C), the post-sintering waste pulverized in the step (B) is mixed with an aqueous solvent to produce a slurry, and then the first separated matter and the second separated matter are recovered using the magnet.

[0176] <4> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <3>, wherein in the step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or more and 2.5 or less by adding the mineral acid having no oxidizing power.

[0177] <5> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <4>, wherein in the step (E), the second metal solution is adjusted to a pH of 9 or more and 10 or less by adding the ammonia water.

[0178] <6> The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <5>, wherein the first metal element is Ni.

[0179] <7> The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <6>, wherein the second metal element is Cu.

[0180] <8> The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <7>, wherein the ceramic particles are BaTiO3.

[0181] <9> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <8>, wherein the rare earth component is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0182] <10> (A) a step of preparing fired waste of a multilayer ceramic capacitor, the fired waste comprising: a laminate including ceramic layers and internal electrode layers; fired electrode layers disposed on the laminate and connected to the internal electrode layers; and a first-stage plating layer disposed on the fired electrode layer as an outermost layer, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth-containing materials containing rare earth components are contained in grain boundaries between the plurality of ceramic particles; the internal electrode layers contain a first metal component which is a magnetic base metal; the fired electrode layers contain a second metal component which is a non-magnetic noble metal; the first-stage plating layer contains the first metal component; and the ceramic layers, the internal electrode layers, and the fired electrode layers are sintered; (B) a step of pulverizing the fired waste to obtain a ceramic fine-grained product in which the ceramic layer has been pulverized, a first metal fine-grained product in which the rare earth-containing material, the internal electrode layer, and the first-stage plating layer have been pulverized, and a second metal fine-grained product in which the baked electrode layer has been pulverized; (C) a step of using a magnet to separate and recover the fired waste after the step (B) into a first separated product containing the ceramic fine-grained product and the first metal fine-grained product, and a second separated product containing the ceramic fine-grained product, the rare earth-containing material, and the second metal fine-grained product; (D) a step of dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine-grained product and the second metal fine-grained product in the second separated product and producing a rare earth component-containing solution in which the rare earth component in the rare earth-containing material has been dissolved; (E) dissolving the ceramic microparticles and the second metal microparticles in the second separated product that have precipitated in step (D) in ammonia water to precipitate the ceramic microparticles in the second separated product and to produce a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

[0183] <11> (A) a step of preparing fired waste of a multilayer ceramic capacitor, the fired waste comprising: a laminate including ceramic layers and internal electrode layers; fired electrode layers disposed on the laminate and connected to the internal electrode layers; a first-stage plating layer disposed on the fired electrode layers; and a second-stage plating layer disposed on the first-stage plating layer as an outermost layer, the ceramic layers having aggregates of a plurality of ceramic particles, and rare earth-containing substances containing rare earth components are contained in grain boundaries between the plurality of ceramic particles; the internal electrode layers contain a first metal component which is a magnetic base metal; the fired electrode layers contain a second metal component which is a non-magnetic noble metal; the first-stage plating layer contains the first metal component; the second-stage plating layer contains a third metal component; and the ceramic layers, the internal electrode layers, and the fired electrode layers are sintered; (K) removing at least the second-stage plating layer from the fired waste, of the first-stage plating layer and the second-stage plating layer; (B) micronizing the fired waste from which at least the second-stage plating layer has been removed by passing through the step (K) to obtain a ceramic micronized product in which the ceramic layer has been micronized, the rare earth-containing material, a first metal micronized product in which the internal electrode layer and the first-stage plating layer have been micronized, and a second metal micronized product in which the baked electrode layer has been micronized; (C) using a magnet to separate and recover the fired waste after passing through the step (B) into a first separated product containing the ceramic micronized product and the first metal micronized product, and a second separated product containing the ceramic micronized product, the rare earth-containing material, and the second metal micronized product. (D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic finely divided product and the second metal finely divided product in the second separated product and generating a rare earth component-containing solution in which the rare earth component in the rare earth-containing product is dissolved;(E) dissolving the ceramic microparticles and the second metal microparticles in the second separated product that have precipitated in step (D) in ammonia water to precipitate the ceramic microparticles in the second separated product and to produce a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

[0184] 10: Multilayer ceramic capacitor 12: Laminate 12a: First main surface 12b: Second main surface 12c: First side surface 12d: Second side surface 12e: First end surface 12f: Second end surface 14: Ceramic layer 14_U: Unsintered ceramic layer 16: Internal electrode layer 16_U: Unsintered internal electrode layer 16a: First internal electrode layer 16b: Second internal electrode layer 30: External electrode 30a: First external electrode 30b: Second external electrode 32: Baked electrode layer 32a: First baked electrode layer 32b: Second baked electrode layer 34: Plating layer 34a: First plating layer 34b: Second plating layer 34a1 : First lower plating layer 34a2 : First upper plating layer 34b1 : Second lower plating layer 34b2 : Second upper plating layer x : Height direction y : Width direction z : Length direction

Claims

1. (A) A post-firing waste of a multilayer ceramic capacitor comprising a laminate including a ceramic layer and an internal electrode layer, and a sintered electrode layer disposed on the laminate as the outermost layer and connected to the internal electrode layer, wherein the ceramic layer has aggregates of a plurality of ceramic particles, the grain boundaries between the plurality of ceramic particles contain rare earth components, the internal electrode layer contains a first metal component which is a base metal having magnetism, the sintered electrode layer contains a second metal component which is a noble metal that does not have magnetism, and the ceramic layer, the internal electrode layer and the sintered electrode layer are sintered, a step of preparing post-firing waste of a multilayer ceramic capacitor, (B) A step of obtaining a ceramic granule in which the ceramic layer has been granulated, a first metal granule in which the rare earth-containing material and the internal electrode layer have been granulated, and a second metal granule in which the baked electrode layer has been granulated, by granulating the waste after firing, (C) A step of separating and recovering the post-fired waste after going through step (B) using a magnet into a first separated material containing the ceramic granules and the first metal granules, and a second separated material containing the ceramic granules, the rare earth-containing material and the second metal granules, (D) A step of dissolving the second separated product after step (C) in at least one mineral acid selected from the group including dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second separated product and generating a rare earth component-containing solution in which the rare earth components in the rare earth-containing product are dissolved, (E) A step of dissolving the ceramic microparticles and the second metal microparticles in the second separated material that have precipitated in step (D) in aqueous ammonia, thereby precipitating the ceramic microparticles in the second separated material and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved, A method for separating and recovering rare earth and metal components from waste materials after firing of multilayer ceramic capacitors, comprising the following:

2. A method for separating and recovering rare earth components and metal components from waste materials after firing of multilayer ceramic capacitors according to claim 1, further comprising the step of (I) dissolving the first separated material after step (C) in at least one mineral acid selected from the group including sulfuric acid, nitric acid, and hydrochloric acid, thereby precipitating the ceramic microparticles in the first separated material and generating a first metal solution in which the first metal component contained in the first metal microparticles in the first separated material is dissolved.

3. The method for separating and recovering rare earth components and metal components from post-firing waste of multilayer ceramic capacitors according to claim 1 or 2, wherein in step (C), the post-firing waste that has been pulverized in step (B) is mixed with an aqueous solvent to produce a slurry, and then the first separated material and the second separated material are recovered using the magnet.

4. The method for separating and recovering rare earth components and metal components from waste materials after firing of multilayer ceramic capacitors according to claim 1 or 2, wherein in step (D), the solution containing rare earth components is adjusted to have a pH of 1.5 or higher and a pH of 2.5 or lower by adding the mineral acid that does not have oxidizing power.

5. The method for separating and recovering rare earth components and metal components from waste materials after firing of multilayer ceramic capacitors according to claim 1 or 2, wherein in step (E), the second metal solution is adjusted to have a pH of 9 or higher and a pH of 10 or lower by adding the ammonia water.

6. The method for separating and recovering rare earth components and metal components from waste materials after firing of multilayer ceramic capacitors according to claim 1 or 2, wherein the first metal component is Ni.

7. The method for separating and recovering rare earth components and metal components from waste materials after firing of multilayer ceramic capacitors according to claim 1 or 2, wherein the second metal component is Cu.

8. The ceramic particles are BaTiO 3 A method for separating and recovering rare earth components and metal components from waste materials after firing of multilayer ceramic capacitors according to claim 1 or 2.

9. The method for separating and recovering rare earth components and metal components from waste materials after firing of multilayer ceramic capacitors according to claim 1 or 2, wherein the rare earth component is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

10. (A) Waste after firing of a multilayer ceramic capacitor comprising a laminate including a ceramic layer and an internal electrode layer, a baked electrode layer disposed on the laminate and connected to the internal electrode layer, and a first-stage plating layer disposed on the baked electrode layer as the outermost layer, wherein the ceramic layer has aggregates of a plurality of ceramic particles, the grain boundaries between the plurality of ceramic particles contain rare earth components, the internal electrode layer contains a first metal component which is a base metal having magnetism, the baked electrode layer contains a second metal component which is a noble metal that does not have magnetism, the first-stage plating layer contains the first metal component, and the ceramic layer, the internal electrode layer and the baked electrode layer are sintered, a step of preparing waste after firing of a multilayer ceramic capacitor, (B) A step of obtaining a ceramic micronized material in which the ceramic layer has been micronized, a first metal micronized material in which the rare earth-containing material, the internal electrode layer and the first-stage plating layer have been micronized, and a second metal micronized material in which the baked electrode layer has been micronized, by micronizing the waste after firing, (C) A step of separating and recovering the post-fired waste after going through step (B) using a magnet into a first separated material containing the ceramic granules and the first metal granules, and a second separated material containing the ceramic granules, the rare earth-containing material and the second metal granules, (D) A step of dissolving the second separated product after step (C) in at least one mineral acid selected from the group including dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second separated product and generating a rare earth component-containing solution in which the rare earth components in the rare earth-containing product are dissolved, (E) A step of dissolving the ceramic microparticles and the second metal microparticles in the second separated material that have precipitated in step (D) in aqueous ammonia, thereby precipitating the ceramic microparticles in the second separated material and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved, A method for separating and recovering rare earth and metal components from waste materials after firing of multilayer ceramic capacitors, comprising the following:

11. (A) Waste after firing of a multilayer ceramic capacitor comprising a laminate including a ceramic layer and an internal electrode layer, a baked electrode layer disposed on the laminate and connected to the internal electrode layer, a first-stage plating layer disposed on the baked electrode layer, and a second-stage plating layer disposed on the first-stage plating layer as the outermost layer, wherein the ceramic layer has aggregates of a plurality of ceramic particles, the grain boundaries between the plurality of ceramic particles contain rare earth components, the internal electrode layer contains a first metal component which is a base metal having magnetism, the baked electrode layer contains a second metal component which is a noble metal that does not have magnetism, the first-stage plating layer contains the first metal component, the second-stage plating layer contains a third metal component, and the ceramic layer, the internal electrode layer and the baked electrode layer are sintered, a step of preparing waste after firing of a multilayer ceramic capacitor, (K) A step of removing at least the second plating layer from the first plating layer and the second plating layer in the waste after firing, (B) A step of micronizing the post-fired waste from which at least the second-stage plating layer has been removed by going through the above step (K), thereby obtaining a first metal micron product in which the ceramic layer has been micronized, the rare earth-containing material, the internal electrode layer and the first-stage plating layer have been micronized, and a second metal micron product in which the baked electrode layer has been micronized, (C) A step of separating and recovering the post-fired waste after step (B) using a magnet into a first separated material containing the ceramic granules and the first metal granules, and a second separated material containing the ceramic granules, the rare earth-containing material and the second metal granules, (D) A step of dissolving the second separated product after step (C) in at least one mineral acid selected from the group including dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second separated product and generating a rare earth component-containing solution in which the rare earth components in the rare earth-containing product are dissolved, (E) A step of dissolving the ceramic microparticles and the second metal microparticles in the second separated material that have precipitated in step (D) in aqueous ammonia, thereby precipitating the ceramic microparticles in the second separated material and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved, A method for separating and recovering rare earth and metal components from waste materials after firing of multilayer ceramic capacitors, comprising the following: