Method for manufacturing blast waste and method for manufacturing metal raw materials for recycling

Abstract

The present invention aims to provide a technique for increasing the concentration rate of metal elements by magnetic separation in a method for recovering metal elements using a blast treatment method. [Solution] The blast scrap obtained by a method for producing blast scrap, which includes a step of blasting a laminate comprising a base material and a target metal-containing layer laminated on the base material using a magnetic blast material with a magnetic susceptibility higher than that of the target metals, can improve the concentration rate of metal elements by magnetic separation.

Description

Technical Field

[0001] The present invention relates to a technique for recovering metals from a laminate having a metal-containing layer on its surface.

Background Art

[0002] In industrial products, many functional members having a structure in which a layer containing a metal element is laminated on the surface are used. The metal element is often a valuable metal, and it is important to recover it from industrial products for recycling.

[0003] [[ID=Is known a blasting process in which particles called blasting materials or abrasives are sprayed as a method for removing the metal element-containing layer from a laminate having a metal element-containing layer on its surface. Further, a method for recovering target metals from blasting waste by magnetic separation has been proposed.

[0004] For example, in Patent Document 1, there is proposed a method for recovering particulate matter containing platinum group elements by magnetic separation, the method comprising a separation step of separating the particulate matter into magnetic and non-magnetic substances by magnetic separation, and a re-separation step of separating the non-magnetic substances obtained in the separation step into magnetic and non-magnetic substances by magnetic separation. In this technique, a non-magnetic material (alumina, silicon carbide, etc.) is used as the blasting material, and a magnetic material is used as the valuable metal. Since the blasting material after the blasting treatment is in a form in which the valuable metal is firmly bonded, the magnetic substances obtained by magnetic separation contain the blasting material to which the valuable metal is attached. Patent Document 1 specifically describes that by this technique, in a single magnetic separation of the blasting waste, for Pt, it is concentrated from 0.3% in the blasting waste to 3.5% in the magnetic substances, and for Ru, it is concentrated from 1.7% in the blasting waste to 19.1% in the magnetic substances.

[0005] Patent Document 2 proposes a method for recovering platinum and ruthenium, comprising the steps of: recovering the magnetically deposited material by magnetically separating the blast-treated material obtained by blast-treating the surface of a substrate to which platinum and ruthenium are attached using a non-magnetic blasting material; and recovering platinum and ruthenium from the magnetically deposited material. Patent Document 2 specifically states that, using this technology, the recovered magnetically deposited material contains 14.83 to 26.49% alumina, which is the blasting material, and the concentration ratio, which is the ratio of the content of magnetically deposited material to the content in the blast-treated material, is 5.5 to 31.3 times for Pt and 4.7 to 28.3 times for Ru. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-241247 [Patent Document 2] Japanese Patent Publication No. 2012-179554 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The methods described in Patent Documents 1 and 2 both use non-magnetic materials as the blasting material, and the target metal element is recovered as magnetic deposits while attached to the blasting material. In other words, in the magnetic deposits, which are the recovered fraction by magnetic separation, the target metal element is inevitably accompanied by the blasting material. For this reason, the concentration ratio, which is the metal element content in the recovered magnetic deposits relative to the metal element content in the blasting scrap before magnetic separation, is at most only a few tens of times.

[0008] However, methods that only yield a concentration of a few tens of times at best through magnetic separation cannot be said to have sufficient recovery efficiency.

[0009] Therefore, the object of the present invention is to provide a technique for increasing the concentration rate of metal elements by magnetic separation in a method for recovering metal elements using a blast treatment method. [Means for solving the problem]

[0010] As a result of diligent research, the inventors have discovered that by using a magnetic material with a higher magnetic susceptibility than the metals to be recovered as the blasting material used in blasting, the concentration rate of metals by magnetic separation in the resulting blasting waste can be dramatically improved. This invention was completed by further research based on this finding.

[0011] In other words, the present invention provides inventions in the following embodiments. Item 1. A method for producing blast scrap, comprising the step of blasting a laminate including a base material and a layer containing target metals laminated on the base material using a magnetic blasting material with a magnetic susceptibility higher than that of the target metals. Item 2. The manufacturing method described in Item 1, wherein the target metal is a catalyst. Item 3. The manufacturing method according to item 1 or 2, wherein the target laminate is an electrode. Item 4. The manufacturing method according to any one of items 1 to 3, wherein the metals include a metallic element selected from the group consisting of Au, Ag, Pt, Pd, Ir, Os, Ru, and Rh. Item 5. The manufacturing method according to any one of items 1 to 4, wherein the magnetic blast material is a soft magnetic material. Item 6. The manufacturing method according to any one of Items 1 to 5, wherein the magnetic blast material is magnetic stainless steel. Item 7. The manufacturing method according to any one of items 1 to 6, wherein the average particle size of the magnetic blast material is 100 to 800 μm. Item 8. The manufacturing method according to any one of items 1 to 7, wherein the average particle size of the blast debris is 100 to 800 μm. Item 9. A method for producing metal raw materials for recycling, comprising the step of separating the target metals and the magnetic blasting material by subjecting the blasting waste obtained by blasting a laminate including a base material and a layer containing target metals laminated on the base material using a magnetic blasting material with a magnetic susceptibility higher than that of the target metals to magnetic separation. [Effects of the Invention]

[0012] According to the present invention, a technique is provided for increasing the concentration rate of metal elements by magnetic separation in a method for recovering metal elements using a blast treatment method. [Modes for carrying out the invention]

[0013] [1. Method for manufacturing blast chips] The present invention relates to a method for manufacturing blast scrap, characterized by comprising the step of blasting a laminate, which includes a base material and a layer containing target metals laminated on the base material, using a magnetic blasting material with a magnetic susceptibility higher than that of the target metals. The present invention relates to a method for manufacturing blast scrap, and will be described in detail below.

[0014] [1-1. Laminates] The laminate includes a base material and a layer containing the target metals laminated on the base material.

[0015] The target metals can be any substance containing a metallic element, such as elemental metals, metal oxides, metal sulfides, or alloys. In the manufacturing method of the present invention, the target metals may be one of these forms alone or a combination of two or more.

[0016] The metal element is not particularly limited, as long as the magnetic susceptibility of the target metals containing the metal element is lower than the magnetic susceptibility of the blast material. Since the blast scrap obtained by the manufacturing method of the present invention has excellent concentration efficiency of metal elements, it is preferable that the metal element be a rare metal, specifically, gold (Au), silver (Ag), platinum (Pt), palladium (Pd), iridium (Ir), osmium (Os), ruthenium (Ru), and rhodium (Rh). The type of metal element contained in the blast scrap may be a single type or a combination of two or more types. Among these metal elements, gold, silver, platinum, iridium, osmium, ruthenium, and rhodium are preferred in terms of easily obtaining the effects of the present invention, gold, silver, iridium, osmium, and ruthenium are more preferred, and iridium is even more preferred.

[0017] Among these target metals, metal oxides are preferable, and iridium oxide is more preferable.

[0018] The target metals are not particularly limited in terms of their use, and examples include catalysts, circuits, etc. Among these uses, generally, the particles of the target metal are fine and exposed on the surface, and it is presumed that they can be easily peeled off from the base material by blasting and the adhesion to the blasting material or the base material can be suppressed. Therefore, a catalyst is preferably used. In the method for producing blast debris of the present invention, the target metals used as raw materials are usually in the form after their use. Therefore, as the target metals, usually, waste catalysts, waste circuits, and waste materials or scraps generated in their manufacturing processes are included, and waste catalysts are preferably included.

[0019] The mode in which the target metal-containing layer is supported on the base material is not particularly limited. Examples of the non-limited supporting methods include electroplating, dispersion plating, thermal spraying, thermal decomposition method (method by coating and firing), etc. That is, as the target metal-containing layer, an electroplated layer, a dispersion-plated layer, a thermal sprayed layer, a thermal decomposition layer, etc. are included. Among these target metal-containing layers, a thermal sprayed layer is preferably used.

[0020] The material of the base material is not particularly limited, and examples include titanium, titanium alloy, stainless steel (SUS), aluminum alloy, copper alloy, etc. Also, the shape of the base material is not particularly limited, and examples include sheet shape, plate shape, punching board shape, mesh shape, wire shape, rod shape, tubular shape, or a combination of these shapes.

[0021] The laminate is not particularly limited as long as the above-mentioned target metal-containing layer is laminated on the base material. Regarding the lamination mode of the laminate, another phase may be interposed between the surface of the base material and the target metal-containing layer, or may not be interposed. Furthermore, the position of the target metal-containing layer in the laminate is not particularly limited as long as it can be peeled off by the blasting material, and it may form the outermost layer of the laminate or the inner layer of the laminate.

[0022] Specific examples of laminates include electrodes and circuit boards. Specifically, catalytic electrodes are examples of electrodes. In addition, insoluble metal electrodes are examples of electrodes, specifically electrodes in which a titanium substrate is coated with an MMO (composite metal oxide), more specifically DSA (Dimensionally Stable Anode), DSE (Dimensionally Stable Electrode), and even more specifically electrodes in which iridium oxide or ruthenium oxide is coated on a titanium substrate as a target metal-containing layer. Furthermore, examples of electrodes include electrodes for industrial electrolysis, specifically electrodes for oxygen generation (inorganic acid (sulfuric acid, nitric acid, etc.) electrolysis, salt electrolysis, etc.), electrodes for electroplating, electrodes for electrodeposition coating, electrodes for electrolytic casting, electrodes for electrolytic refining, etc. It should be noted that the laminates used as raw materials in the blast scrap manufacturing method of the present invention are usually those that have finished their intended use. Therefore, examples of laminates are usually waste electrodes and waste circuit boards.

[0023] Among these laminates, preferably are electrodes, more preferably catalyst electrodes, even more preferably DSE electrodes, and even more preferably electrodes coated on a titanium substrate with iridium oxide as a target metal-containing layer. Particularly preferred are waste electrodes of these electrodes.

[0024] [1-2. Magnetic blasting materials] As the magnetic blasting material, a magnetic material with a higher magnetic susceptibility than the target metal is used. Here, magnetic susceptibility refers to mass magnetic susceptibility. The specific mass magnetic susceptibility (magnetic susceptibility at 20°C) of the magnetic blasting material is preferably that of a soft magnetic material. Generally, if the magnetic blasting material does not fall off even when vertically suspended after being magnetically attached to the magnetic separation means, it can be judged to have a sufficiently higher magnetic susceptibility than the target metal.

[0025] The specific material of the magnetic blasting material is not particularly limited as long as it satisfies the above-mentioned magnetic susceptibility conditions and has polishing properties. Examples include magnetic stainless steel, iron, nickel, cobalt, and alloys thereof. Furthermore, in this invention, even non-magnetic materials are included as magnetic blasting materials if they can be magnetized by a treatment or processing that imparts magnetism to them.

[0026] Examples of magnetic stainless steel include stainless steel grit [for example, those with a carbon content of 5% by weight or less (e.g., about 2% by weight), a chromium content of 35% by weight or less (e.g., about 30% by weight), and a nickel content of 1% by weight or less], chromium-based stainless steel, magnetic chromium-nickel stainless steel, and the like.

[0027] Examples of chromium-based stainless steels include ferritic stainless steels (those with a Cr content of approximately 18% by weight, more specifically the SUS400 series such as SUS405, SUS410L, SUS430, SUS430J1L, SUS434, etc.; SUH21, SUH409, SUH409L, SUH446, etc.) and martensitic stainless steels (those with a Cr content of approximately 13% by weight, more specifically SUS403, Examples of SUS400 series stainless steels include SUS410, SUS410J1, SUS416, SUS420J1, SUS436J1L, SUS431, SUS440A, SUS440C, etc.; SUH1, SUH3, SUH4, SUH11, SUH600, etc.), and precipitation-hardening stainless steels (compositions with a Cr content of about 17% by weight include SUS600 series stainless steels such as SUS630, SUS631, etc.; SUH616, etc.). Examples of magnetic chromium-nickel stainless steels include magnetic austenitic stainless steels (compositions with a Cr content of about 25% by weight and a Ni content of about 5% by weight include magnetic SUS300 series stainless steels such as SUS329J1, etc.).

[0028] These magnetic blasting materials may be used individually or in combination of two or more types. Among these magnetic blasting materials, magnetic stainless steel is preferred, and stainless steel grid is more preferred.

[0029] The particle size of the magnetic blasting material is not particularly limited, but for example, the average particle size can be 100 to 800 μm, preferably 150 to 650 μm, and more preferably 200 to 500 μm. Here, the average particle size is the 50% integrated value (D) obtained from the volume-based particle size distribution measured by laser diffraction-scattering. 50 ) refers to.

[0030] [1-3. Blasting] The specific method of blasting is not particularly limited, but one method is to blast the laminate with a blasting material, and examples include shot blasting and sandblasting, with sandblasting being preferred.

[0031] Furthermore, in blasting, the blasting material may be sprayed onto the laminate alone, or a combustion inhibitor (such as calcium carbonate) may be sprayed along with the blasting material as appropriate.

[0032] [1-4. Blast debris] The blasting debris obtained by the manufacturing method of the present invention includes peeling powder from the target metal-containing layer and used magnetic blasting material.

[0033] The average particle size of the blast debris obtained by the manufacturing method of the present invention is not particularly limited, but for example, it can be 100 to 800 μm, preferably 150 to 650 μm, more preferably 200 to 500 μm, and even more preferably 300 to 400 μm. Here, the average particle size is the 50% integrated value (D) obtained from the volume-based particle size distribution measured by laser diffraction-scattering. 50 ) refers to.

[0034] The particle size distribution width of the blast chips obtained by the manufacturing method of the present invention ((D 90 -D10 ) / D 50 While not particularly limited, examples include 0.1 to 1.5, preferably 0.4 to 1.2, and more preferably 0.6 to 0.9. 10 and D 90 These are the 10% and 90% integrated values, respectively, obtained from the volume-based particle size distribution measured by laser diffraction and scattering.

[0035] The manufacturing method of the present invention may further include a step of sieving the blast-treated material obtained in the blasting step in order to obtain blast scrap having the above-mentioned average particle diameter or particle size distribution width. A filter, mesh, or the like can be used for sieving. The sieving step may be performed by collecting dust in a bag filter installed in the blasting machine used in the blasting step. In this case, blast scrap can be obtained by removing the dust collected by the bag filter from the blast-treated material.

[0036] [2. Method for manufacturing metal raw materials for recycling] The blast scrap obtained by the method described in "1. Method for Manufacturing Blast Scrap" above has a high concentration rate of metal elements due to magnetic separation, making it suitable for the production of recycled metal raw materials containing said metal elements. Accordingly, the present invention also provides a method for manufacturing recycled metal raw materials using said blast scrap.

[0037] In other words, the present invention provides a method for producing recyclable metal raw materials, which includes a step of separating the target metals from the magnetic blasting material by subjecting a laminate, which comprises a base material and a layer containing target metals laminated on the base material, to magnetic separation. This process involves blasting the resulting blasting waste using a magnetic blasting material with a higher magnetic susceptibility than the target metals.

[0038] The blast scrap and the method for obtaining it are as described in "1. Method for Manufacturing Blast Scrap" above.

[0039] Regarding the magnetic separation method, a person skilled in the art can appropriately select a method in which used magnetic blasting material is magnetically attached to the blasting waste, while the detached powder from the target metal-containing layer is not magnetically attached. The strength of the magnetic force should be such that the used magnetic blasting material is magnetically attached, while the detached powder from the target metal-containing layer is not magnetically attached, and it is sufficient that the blasting material can be separated from the detached powder from the target metal-containing layer by magnetic attachment by bringing a magnet close to or in contact with the blasting waste.

[0040] The non-magnetic material obtained by magnetic separation can be used as a raw material for recycling because the target metals are highly concentrated compared to the blast waste before magnetic separation. [Examples]

[0041] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0042] [Test Example 1] A DSE electrode (waste electrode) was prepared, consisting of a 60cm x 60cm square perforated titanium substrate with a layer containing iridium oxide baked onto it. As the magnetic blasting material, stainless steel grid was prepared (with a composition of Cr content of 35% by weight or less (specifically about 30% by weight), C content of 5% by weight or less (specifically about 2% by weight), Mn content of 1% by weight or less, Si content of 1% by weight or less, Ni content of 1% by weight or less, and the remainder being Fe, with an average particle size of 200-500 μm, and confirmed to be held by magnetic force even when vertically suspended using the Maghand described below). Calcium carbonate was prepared as a combustion inhibitor. A Maghand (HMC-10, Kanetec) was prepared as the magnetic separation device.

[0043] Using a blasting machine (Newma Blaster SGF-4BS, Fuji Seisakusho), a mixture of magnetic blasting material and combustion inhibitor powder was blasted onto the waste electrode for sandblasting treatment. The sandblasting treatment was performed separately on the front side, which had a high iridium oxide coating, and the back side, which had a low iridium oxide coating.

[0044] Blasting debris (front-side blasted debris, back-side blasted debris) accumulated inside the blasting machine was collected from the blasted materials (front-side blasted materials, back-side blasted materials) within the blasting machine. Dust collected by the bag filter was not collected. The particle size of the obtained blasting debris was measured. The results are shown in Table 1.

[0045] [Table 1]

[0046] [Test Example 2] The blast debris (front-side blast debris and back-side blast debris) collected in a tray was magnetically separated by tracing it with the magnetic part of a magnetic separator to capture the magnetically attached materials. The magnetic separation was performed once for each of the front-side and back-side blast debris (i.e., no further magnetic separation was performed on non-magnetic materials or magnetically attached materials after magnetic separation).

[0047] The weights of the blasted debris before magnetic separation (front side blasted debris, back side blasted debris), the non-magnetic material remaining in the tray after magnetic separation, and the captured magnetic material after magnetic separation were measured. Each was then subjected to alkali fusion twice, and the iridium content was analyzed by ICP. The results are shown in Tables 2 and 3.

[0048] [Table 2]

[0049] [Table 3]

[0050] As shown in Tables 2 and 3, the magnetically deposited material obtained by magnetic separation did not contain iridium, thus completely separating the target metals into the non-magnetic material. Furthermore, magnetic separation resulted in iridium enrichment ratios of 60.5 and 163 times, achieving extremely high enrichment rates.

Claims

1. A method for producing blast scrap, comprising the step of blasting a laminate including a base material and a layer containing target metals laminated on the base material using a magnetic blasting material with a magnetic susceptibility higher than that of the target metals.

2. The manufacturing method according to claim 1, wherein the target metals are catalysts.

3. The manufacturing method according to claim 1, wherein the target laminate is an electrode.

4. The manufacturing method according to any one of claims 1 to 3, wherein the metals include a metallic element selected from the group consisting of Au, Ag, Pt, Pd, Ir, Os, Ru, and Rh.

5. The manufacturing method according to any one of claims 1 to 3, wherein the magnetic blast material is a soft magnetic material.

6. The manufacturing method according to any one of claims 1 to 3, wherein the magnetic blast material is magnetic stainless steel.

7. The manufacturing method according to any one of claims 1 to 3, wherein the average particle size of the magnetic blast material is 100 to 800 μm.

8. The manufacturing method according to any one of claims 1 to 3, wherein the average particle size of the blast debris is 100 to 800 μm.

9. A method for producing recyclable metal raw materials, comprising the step of separating the target metals and the magnetic blasting material by subjecting the blasting waste obtained by blasting a laminate including a base material and a layer containing target metals laminated on the base material using a magnetic blasting material with a magnetic susceptibility higher than that of the target metals to magnetic separation.

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