Method and apparatus for recycling ruthenium-containing sputter target scrap

Abstract

The application provides a comprehensive recovery method and device for a ruthenium-containing sputtering target waste material, and specifically comprises the following steps: (1) uniformly crushing and mixing a ruthenium-containing sputtering target waste material, a collector, an FeO source and a slagging agent; (2) smelting the mixture to obtain a platinum group metal-rich alloy, a smelting slag and fumes, cooling the fumes and collecting coarse RuO2 and RuO4 in the fumes; and (3) electrolyzing the platinum group metal-rich alloy to obtain anode sludge of the platinum group metal-rich alloy, and further purifying the anode sludge to obtain a platinum group metal-rich material, wherein the platinum group metal-rich material comprises ruthenium metal. The application can efficiently collect ruthenium in the ruthenium-containing sputtering target waste material, and can simultaneously recycle and reuse other platinum group noble metals in the ruthenium-containing sputtering target waste material, and is suitable for comprehensive recycling of valuable metals in industrial waste.

Description

Technical Field

[0001] This invention belongs to the field of solid waste recycling, and in particular relates to a method and apparatus for recycling sputtering target waste. Background Technology

[0002] Platinum group metals (Ru, Rhodium, Pd, Osmium, Irium, and Pt) are widely used in automotive catalysts, petrochemical catalysts, and target materials due to their stable physicochemical properties and unique catalytic performance. However, platinum group metal resources are extremely scarce and sparsely distributed. Currently, the world's proven reserves of platinum group metals are only about 70,000 tons, and 90% of platinum group metal ores are concentrated in South Africa. In my country, platinum group metals are even scarcer, mostly occurring as associated with other metal ores. Extracting platinum group metals from primary ore presents challenges such as low grade, high extraction difficulty, and high cost.

[0003] On the other hand, my country's chemical and other industries generate a large amount of industrial solid waste every year, which urgently needs to be treated. At the same time, this industrial solid waste is also a secondary resource of platinum group metals (PGMs), and the grade of PGMs in the waste is much higher than that in the primary ore. Therefore, recovering PGMs from secondary resources is of great significance for building a resource-recycling society.

[0004] Ruthenium, the least abundant platinum group metal, has an abundance of only 10 in the Earth's crust. -9 Ruthenium is a raw material for chemical synthesis catalysts and electronic devices such as hard disk drives and precious metal sputtering targets. Similar to other platinum group metals, ruthenium extraction tends to focus on recycling secondary resources such as spent catalysts and sputtering targets. The molten oxidative distillation method is currently the mainstream method for ruthenium recovery, mainly including steps such as pretreatment, alkali fusion, oxidative distillation, concentration and drying, and hydrogen reduction. The pretreated waste is added to an alkali fusion agent (KOH + KClO3 / NaOH + NaNO3 / Na2O2) and fused at 650℃. The melt is then leached with boiling water to obtain a filtrate, which is acidified to yield ruthenium salts in solution, where ruthenium exists in the form of RuO4. 2- RuO4 is obtained by oxidizing and distilling with an oxidizing agent such as Cl2 / NaClO+H2SO4 / MnO2+HCl / KMnO4+NaBiO3; then by atmospheric / vacuum distillation, absorption with hydrochloric acid, and drying to obtain RuCl3·3H2O; finally, ruthenium powder is obtained by hydrogen reduction. This method mainly utilizes the volatile property of RuO4 (boiling point is only 40℃). However, RuO4 is highly toxic and irritating, posing safety hazards to this method, which is only suitable for processing raw materials that are easily dissolved by wet methods.

[0005] There is an urgent need for an efficient and safe method to recover ruthenium metal from industrial solid waste. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that the RuO4 obtained by the existing molten oxidation distillation method for recovering ruthenium from industrial solid waste is highly toxic and has poor safety. To overcome the shortcomings and defects mentioned in the background technology, the present invention provides a comprehensive method and device for the recycling of ruthenium-containing sputtering target waste.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] A method for comprehensive recycling of ruthenium-containing sputtering target waste, characterized in that the method specifically includes the following steps:

[0009] (1) Crushing and mixing the ruthenium-containing sputtering target waste, collector, FeO source and slagging agent;

[0010] (2) The mixture obtained in step (1) is smelted to obtain a platinum group metal alloy, slag and dust. The dust is cooled and the crude RuO2 and RuO4 in the dust are collected.

[0011] (3) Electrolyze the platinum group metal alloy obtained in step (2) to obtain platinum group metal anode mud, and further purify it to obtain platinum and ruthenium metals.

[0012] The recycling method of the present invention recovers ruthenium from ruthenium-containing sputtering target waste through two parts:

[0013] (i) Ruthenium metal obtained by electrolysis: A collector and FeO source are added for smelting. The slag-forming agent and FeO source are used to reduce the melting point and viscosity of the ruthenium-containing sputtering target waste, promote the enrichment of platinum group metals in it by the collector, and facilitate the obtaining of platinum group metal-rich alloys. The platinum group metal-rich alloys are electrolyzed to obtain platinum group metal-rich anode mud, which is further purified to obtain high-purity platinum group metal-rich ruthenium metal. When the sputtering target waste contains other platinum group metals, it will also contain precious metals such as platinum.

[0014] (ii) Ruthenium oxides volatilized during smelting: By cooling the flue gas, the crude RuO2 and RuO4 volatilized during smelting can be collected, which can not only prevent the escape of toxic gases, but also improve the recovery rate of ruthenium metal.

[0015] Preferably, the ruthenium-containing sputtering target waste is alumina-based, the alumina matrix content in the ruthenium-containing sputtering target waste is >30wt.%, and the ruthenium content in the ruthenium-containing sputtering target waste is 100-1,000,000 g / t.

[0016] Table 1. Main components of alumina-based sputtering target powder

[0017]

[0018] Table 1 shows the main components of alumina-based sputtering target powder waste. The valuable components are mainly platinum group metals platinum and ruthenium. If a traditional wet recycling process is used, the alumina matrix will encapsulate the platinum group metals (e.g., platinum and ruthenium). Figure 2 As shown in the figure, this leads to a decrease in the leaching rate of platinum group metals, and the large amount of waste acid and waste liquid generated will increase costs.

[0019] This smelting and recycling method solves the problem of low precious metal recovery rate in the wet recovery of alumina-based sputtering target powder. Considering the high melting point of alumina, separate processing requires heating to over 2000℃, resulting in high energy consumption and high recovery costs. The present invention mixes alumina with an FeO source and a slagging agent. Based on the distribution of the liquid phase region in the CaO-SiO2-Al2O3-(FeO) phase diagram, an optimal ratio exists that can lower the melting point of the mixture to approximately 1350℃, achieving low-temperature smelting. During the smelting process, the melting of alumina eliminates its encapsulation of platinum group metals, improving the recovery rate of platinum group metals.

[0020] Alumina-based sputtering target powder waste is not limited to this type of industrial solid waste, but also includes one or more catalysts for automotive exhaust purification and petrochemical industries, thus broadening the scope of recycling.

[0021] More preferably, the ruthenium-containing sputtering target waste contains platinum group metals, including platinum 100-1000000 g / t, palladium 100-9000 g / t, rhodium 100-6000 g / t and ruthenium 100-1000000 g / t; the platinum-rich group metals in step (3) include platinum, palladium, rhodium and ruthenium.

[0022] Ruthenium-containing sputtering target waste often also contains platinum group metals other than ruthenium, and the other platinum group metals are more expensive. The processing solution of this invention can recover ruthenium while also recovering the other platinum group metals, and has a high recovery rate for the other platinum group metals.

[0023] Preferably, the collector in step (1) includes copper. Copper is chosen as the platinum group metal collector because it has a low melting point, which can reduce the energy consumption of the collection process. At the same time, the alloy obtained from copper collection can be used in existing copper electrolysis equipment in smelters to obtain anode mud, which can further enrich the platinum group metals.

[0024] The FeO source includes industrial waste containing FeO, wherein the FeO mass content is 60-99 wt.% of the FeO source, and the slag-forming agent includes limestone and / or silica sand. The resulting slag system is CaO-SiO2-Al2O3-FeO. Using the CaO-SiO2-Al2O3 ternary phase diagram, the following proportions of slag have relatively low melting points: In the CaO-Al2O3-SiO2 ternary slag system, the contents of CaO, SiO2, and Al2O3 are 39% CaO, 44% SiO2, and 17% Al2O3, respectively. Adding a certain amount of FeO to this ternary slag system can further reduce the slag melting point and viscosity.

[0025] The FeO-containing industrial waste includes one or more of the following: slag obtained from steelmaking furnace dust treatment, rotary kiln slag, or converter slag. Using FeO-containing industrial waste allows for the production of slag containing a certain amount of FeO even after smelting, lowering the slag's melting point and viscosity, promoting the enrichment of platinum group metals in the slag towards copper, and increasing the collection rate of platinum group metals.

[0026] Preferably, the amount of collector added is 0.2-5.0 times the mass of the ruthenium-containing sputtering target waste. If the amount of collector is too small, the contact area between the collector and the platinum group metals is too small, resulting in a low collection rate of the platinum group metals; if the amount of collector is too large, subsequent processes require separation of the collector from the platinum group metals, increasing the separation burden and costs of those processes. Controlling the mass ratio as described above can better balance these factors.

[0027] More preferably, the mass of the collector is 0.5-2 times the mass of the ruthenium-containing sputtering target waste; even more preferably, the mass of the collector is 0.5 times the mass of the ruthenium-containing sputtering target waste.

[0028] Preferably, the slag described in step (2) is mixed with copper concentrate for smelting to further recover the platinum group metals involved in the slag.

[0029] The dust obtained in step (2) of this invention also contains some precious metals, which can be returned to the smelting step for recycling.

[0030] Preferably, the slag comprises CaO, SiO2, Al2O3, and FeO, wherein the mass percentage of CaO is 30-50% of the total mass of the three metal oxides, the mass percentage of SiO2 is 30-50% of the total mass of the three metal oxides, the mass percentage of Al2O3 is 10-40% of the total mass of the three metal oxides, and the mass percentage of FeO is 2-20% of the total mass of the slag.

[0031] The determination of the above-mentioned slag can yield slag with low melting point and low viscosity, which is beneficial for the efficient capture of platinum group metals.

[0032] Preferably, the melting temperature in step (2) is 1300-1600℃ and the melting time is 1-4h.

[0033] More preferably, when the collector is a copper collector, the smelting temperature is 1300-1450℃.

[0034] More preferably, when the collector is an iron collector, the smelting temperature is 1500-1600℃.

[0035] Under the same technical concept, the present invention also provides a comprehensive recycling device for ruthenium-containing sputtering target waste. The recycling device includes a smelting device, a collecting device, and a ventilation device. The smelting device includes a heating device and a reaction vessel disposed inside the heating device. The collecting device is disposed above the reaction vessel, and the ventilation device is disposed above the heating device.

[0036] The reason for adding collection and ventilation devices is that ruthenium oxides (RuO2 or RuO4) are generated during the smelting process. Ruthenium oxides are extremely irritating and toxic; RuO4, in particular, has a boiling point of only 40°C and is highly volatile during the smelting process, leading to safety accidents. Therefore, it is necessary to collect the volatile RuO4. The collection device is used to cool and crystallize the volatile RuO4 on the inner wall of the device (the product is RuO4 and / or RuO4), thereby improving the overall recovery rate of ruthenium. At the same time, the ventilation device is used to treat the fumes and dust, preventing the escape of toxic and harmful ruthenium oxides.

[0037] Preferably, the heating device includes an induction furnace, the reaction vessel includes a graphite crucible, and the collection device includes an oxide crucible, more preferably an alumina and / or zirconium oxide crucible. The oxide crucible is placed upside down above the graphite crucible. The reason for using an oxide ceramic crucible is that this type of material is not induction heated and can maintain a low temperature, which is conducive to cooling and collecting ruthenium oxide in the flue gas. The recovery device is also equipped with an electrolysis device, and the recovered platinum group metal alloy is sent to the electrolysis device for electrolysis.

[0038] The reason why this invention preferably uses a graphite crucible for induction heating is that the graphite crucible does not require the addition of a carbonaceous reducing agent and does not require the introduction of gases such as argon or nitrogen, and can also form a weak reducing atmosphere in the furnace. On the one hand, this facilitates the reduction of trace amounts of platinum group metal oxides in the waste, ensuring that the platinum group metals are in contact with the collector in a metallic state, thereby improving the collection rate; on the other hand, the weak reducing atmosphere can prevent the excessive reduction of FeO in the slag, reducing the Fe impurity content in the alloy, while ensuring that the slag contains a certain amount of FeO, lowering the melting point and viscosity of the slag, promoting the enrichment of platinum group metals in the slag into the collector, and improving the collection rate.

[0039] The electrolysis device can be directly connected to the conventional equipment in the copper electrolysis industry, which has the following advantages: First, the electrolysis device can not only electrolyze the anode mud obtained in steps (1) and (2), but also obtain platinum group precious metals such as platinum, palladium, and rhodium that can be obtained in conventional electrolysis treatment during the electrolysis process, so as to realize the comprehensive recovery of metal elements; Second, it is compatible with conventional electrolysis devices, which is convenient for personnel in this field to operate, has a wide range of applications, and is relatively low in cost.

[0040] The beneficial effects of this invention are as follows:

[0041] (1) This invention can recycle sputtering target powder, especially ruthenium-containing sputtering target powder with alumina matrix, and has a good recovery effect. It can solve the problem of low recovery rate caused by platinum group metals being coated by alumina in traditional wet processing. Using the recovery method of this invention, ruthenium can be efficiently and safely recovered through collection and cooling, and other platinum group metals can also be efficiently recovered through electrolysis;

[0042] (2) This invention provides a method for recycling ruthenium-containing sputtering target waste. By adding a slag-forming agent without fluoride and industrial solid waste containing FeO, the melting point and viscosity of the slag are reduced, and the platinum group metals in the slag are enriched into the collector copper. This method can efficiently enrich ruthenium and other platinum group metals in the ruthenium-containing sputtering target waste.

[0043] (3) The present invention proposes a comprehensive recycling device for ruthenium sputtering target powder, including a smelting device, a collection device, a ventilation device and an electrolysis system. The collection device enables the volatile ruthenium oxide generated during the smelting process to be cooled and collected on the inner wall of the oxide crucible, thereby improving the ruthenium recovery rate. At the same time, the ventilation device can prevent the ruthenium oxide fumes from escaping, ensuring the safety of on-site operation. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a process flow diagram of the method for recovering platinum group metals platinum and ruthenium from alumina-based sputtering target powder waste according to the present invention.

[0046] Figure 2 This is a schematic diagram of the structure of the alumina-based ruthenium-containing sputtering target waste of the present invention.

[0047] Figure 3 This is a schematic diagram of the structure of the recycling device of the present invention;

[0048] The components include: 1. reaction vessel; 2. collection device; 3. heating device; 4. ventilation device; and 5. induction coil. Detailed Implementation

[0049] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0050] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0051] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0052] Example 1:

[0053] The comprehensive recycling device for ruthenium-containing sputtering target waste used in this invention is specifically as follows: Figure 3 As shown in the (recovery device diagram), the recovery device includes: a smelting device, a collection device 2 and a ventilation device 4. The smelting device is the main site of the smelting reaction. The collection device 2 is located inside the smelting device. The ventilation device 4 is located directly above the smelting device and is used to collect the reaction fumes that overflow from the smelting device.

[0054] The smelting device consists of a heating device 3 as the main heating element and a reaction vessel 1 inside the heating device 3. The heating device 3 is an induction furnace, and an induction coil 5 is installed inside the induction furnace. The reaction vessel 1 is a graphite crucible placed inside the induction furnace, and the induction coil 5 is evenly surrounding the graphite crucible.

[0055] The collecting device 2 is an alumina crucible with the same diameter as the graphite crucible. The alumina crucible is placed upside down on top of the graphite crucible in the reaction vessel 1.

[0056] The exhaust device 4 is located above the heating device 3, directly opposite the upper opening of the heating device 3. The exhaust device has suction power and can generate negative pressure within the range to collect smoke and dust.

[0057] A method for comprehensive recycling of ruthenium-containing sputtering target waste, the steps of which are as follows: Figure 1 As shown, the specific steps include:

[0058] Using 320g of ruthenium-containing sputtering target waste as raw material, its main chemical composition is: 90wt.% aluminum oxide, 1320ppm platinum, and 2500ppm ruthenium. The structural characteristics of the sputtering target powder are as follows: Figure 2 As shown.

[0059] Copper, ruthenium-containing sputtering target waste, FeO-containing industrial waste (containing 95 wt.% FeO), and slag-forming agents limestone and silica were crushed, mixed, and placed in a graphite crucible of a smelting apparatus; the amount of copper was 2.5 times the amount of sputtering target powder. The graphite crucible was heated in an induction furnace at 1500℃ for 2 hours to obtain a platinum-rich group metal alloy and slag. Ruthenium oxide (RuO2 or RuO4) was collected from the fumes collected by cooling the inner wall of the alumina crucible. Toxic ruthenium oxide escaping from the joint between the two crucibles was collected at the top of the furnace using an exhaust system 4.

[0060] The total amount of slag is 1000g. FeO accounts for 5% of the mass fraction of the four main components CaO-Al2O3-SiO2-FeO in the slag. In the CaO-Al2O3-SiO2 ternary slag system, the contents of CaO, SiO2 and Al2O3 are 39% CaO, 44% SiO2 and 17% Al2O3, respectively.

[0061] Electrolysis of platinum group metal alloys yields cathode copper, which can be used as a scavenging agent. The resulting Pt and Ru-rich anode mud is used for wet separation and purification to obtain high-purity Pt and Ru. Ruthenium oxides (RuO2, RuO4) collected by cooling the inner wall of the alumina crucible are sold as crude ruthenium products. The slag can be sold as a feedstock for copper smelting, recovering residual platinum group metals.

[0062] In this embodiment, the element recovery rate is calculated as the mass of each element in the product divided by the mass of each element in the raw materials. The mass of the slag and platinum-rich group metal alloy obtained after the reaction, as well as the concentration of each element, were measured. The experimental data are shown in Table 2. The mass of the dust in the exhaust system could not be accurately measured and is not listed in the table. Element content was determined using ICP-OES. The calculated recovery rate of platinum was 98%, and the overall recovery rate of ruthenium (alloy trapping recovery rate + crucible inner wall recovery rate) was 85%.

[0063] In commercial applications, sputtering target waste is mainly recycled for its relatively expensive precious metals such as Pt, without considering the recycling value of Ru. When the waste is sold, it is generally priced only for Pt. However, this solution involves comprehensive recycling, which can not only recover precious metals but also Ru. The recovered Ru can be used as net profit, making it highly economically feasible.

[0064] Table 2. Recovery rates of Pt and Ru in the recovery method of Example 1

[0065]

[0066]

[0067] Example 2:

[0068] The device used in this embodiment is the same as that in Embodiment 1.

[0069] Using 320g of ruthenium-containing sputtering target waste as raw material, its main chemical components are: calcium oxide 25wt.%, silicon dioxide 35wt.%, aluminum oxide 30wt.%, platinum 1000ppm, and ruthenium 2000ppm.

[0070] Copper, ruthenium-containing sputtering target waste, FeO-containing industrial waste (containing 95 wt.% FeO), and slag-forming agents limestone and silica are crushed, mixed, and placed in a graphite crucible of a smelting apparatus; the amount of copper used is 2.5 times the amount of sputtering target powder. The graphite crucible is heated in an induction furnace at 1500℃ for 2 hours to obtain an alloy and slag. Ruthenium oxide (RuO2 or RuO4) is collected by cooling the flue gas on the inner wall of the alumina crucible. Toxic ruthenium oxide escaping from the joint between the two crucibles is collected at the top of the furnace using an exhaust system 4.

[0071] The total amount of slag is 1000g. FeO accounts for 5% of the mass fraction of the four main components CaO-Al2O3-SiO2-FeO in the slag. In the CaO-Al2O3-SiO2 ternary slag system, the contents of CaO, SiO2 and Al2O3 are 39% CaO, 44% SiO2 and 17% Al2O3, respectively.

[0072] Electrolysis of platinum group metal alloys yields cathode copper, which can be used as a scavenging agent. Pt and Ru-rich anode mud is then used for wet separation and purification to obtain high-purity Pt and Ru. Ruthenium oxides (RuO2, RuO4) collected by cooling the inner wall of an alumina crucible are sold as crude ruthenium. The slag can be sold as a feedstock for copper smelting, further recovering residual platinum group metals.

[0073] In this embodiment, the element recovery rate = mass of each element in the product / mass of each element in the raw material. Experimental data are shown in Table 3. The mass of dust in the exhaust system could not be accurately measured and is not listed in the table. Element content was determined using ICP-OES. Calculations showed that the platinum recovery rate was 99%, and the overall ruthenium recovery rate (alloy trapping recovery rate + crucible inner wall recovery rate) was 80%. Considering that the purchase price of this raw material is generally only for the relatively expensive Pt, the recovered Ru can be considered as net profit, making this method highly economically feasible.

[0074] Table 3. Recovery rates of Pt and Ru using this recovery method in Example 2

[0075]

[0076]

Claims

1. A method for comprehensive recycling of ruthenium-containing sputtering target waste, characterized in that, The method specifically includes the following steps: (1) Crushing and mixing ruthenium-containing sputtering target waste, collector, FeO source and slagging agent; the ruthenium-containing sputtering target waste is alumina-based, the content of alumina matrix in the ruthenium-containing sputtering target waste is >30wt.%, and the ruthenium content in the ruthenium-containing sputtering target waste is 100-1000000g / t; (2) The mixture obtained in step (1) is smelted to obtain a platinum group metal alloy, slag and dust. The smelting device includes a heating device (3) and a reaction vessel (1) set inside the heating device (3). A collection device (2) is set above the reaction vessel (1). The reaction vessel (1) is a graphite crucible and the collection device (2) is an oxide crucible. The oxide crucible is set upside down directly above the reaction vessel (1). The upside-down collection device (2) is used to cool the dust, so that the crude RuO2 and RuO4 in the dust condense and are collected on the inner wall of the collection device (2). (3) Electrolyze the platinum group metal alloy obtained in step (2) to obtain platinum group metal anode mud, and further purify it to obtain platinum group metal, wherein the platinum group metal includes ruthenium.

2. The method for comprehensive recycling of ruthenium-containing sputtering target waste as described in claim 1, characterized in that, The ruthenium-containing sputtering target waste contains platinum group metals, including platinum 100-5000 g / t, palladium 100-9000 g / t, rhodium 100-6000 g / t and ruthenium 100-1000000 g / t; the platinum-rich group metals in step (3) include platinum, palladium, rhodium and ruthenium.

3. The method for comprehensive recycling of ruthenium-containing sputtering target waste as described in claim 1, characterized in that, The collector in step (1) includes copper, the FeO source includes industrial waste containing FeO, wherein the FeO mass content is 60-99 wt.% of the FeO source, and the slag-forming agent includes limestone and / or silica sand.

4. The method for comprehensive recycling of ruthenium-containing sputtering target waste as described in claim 3, characterized in that, The amount of the collector added is 2.5-5.0 times the mass of the ruthenium-containing sputtering target waste.

5. The method for comprehensive recycling of ruthenium-containing sputtering target waste as described in claim 1, characterized in that, The slag mentioned in step (2) is mixed into copper concentrate for smelting.

6. The method for comprehensive recycling of ruthenium-containing sputtering target waste as described in claim 5, characterized in that, The slag comprises CaO, SiO2, Al2O3, and FeO. Among CaO, SiO2, and Al2O3, the mass percentage of CaO is 30-50% of the total mass of CaO-Al2O3-SiO2, the mass percentage of SiO2 is 30-50% of the total mass of CaO-Al2O3-SiO2, the mass percentage of Al2O3 is 10-40% of the total mass of CaO-Al2O3-SiO2, and the mass percentage of FeO is 2-20% of the total mass of the slag.

7. The method for comprehensive recycling of ruthenium-containing sputtering target waste as described in claim 1, characterized in that, The melting temperature in step (2) is 1300-1600℃ and the melting time is 1-4h.

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