Method for recovering precious metal from waste precious metal alloy
By using waste precious metal alloys as molten salt electrolysis method in precious metal recycling, and using electrolytic conditions to control the oxidation and deposition of other metals, the problems of complex precious metal recycling process and high energy consumption in the prior art are solved, and the precious metal recycling process in the prior art are realized. High purity and low loss precious metal recycling effect.
Patent Information
- Application Number
- CN202411326629.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2024-12-31
AI Technical Summary
Among the existing precious metal recycling methods, the hydrometallurgy process is complex and produces harmful wastewater, while the pyrometallurgy consumes high energy and high equipment costs, making it difficult to achieve efficient and low-cost precious metal recycling.
Use waste precious metal alloy as anode and inert metal electrode as cathode to form an electrolytic system through molten salt electrolysis, set electrolytic conditions to convert constant current electrolysis into constant voltage electrolysis, and use the oxidation reaction of other metals to separate precious metals from other metals to realize precious metals recycling.
The safe and simple separation of precious metals and other metals is achieved, reducing costs, improving the purity of precious metals and reducing losses.
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Figure CN119221043A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of precious metal recovery, and in particular relates to a method for recovering precious metals from waste precious metal alloys. Background Art
[0002] Precious metals are unevenly distributed around the world and difficult to mine, so these resources are extremely precious. Due to their unique physical and chemical properties, they are widely used in aerospace, electronics, atomic energy, medical, chemical and other fields. The demand for precious metals continues to grow in technological progress and emerging industries, such as the miniaturization of electronic products, the promotion of 5G technology, and the development of renewable energy and electric vehicles, which have put forward new demands for precious metals.
[0003] Waste precious metal alloys are an important part of precious metal secondary resources. Recycling precious metals from waste precious metal alloys can not only improve economic benefits and solve the problem of precious metal resource scarcity in my country, but also help protect the environment. Therefore, studying methods for recovering precious metals from waste precious metal alloys is an effective way to solve the sustainable development of precious metal resources in my country.
[0004] The main methods for recycling waste precious metal alloys are hydrometallurgy and pyrometallurgy. Hydrometallurgy uses chemical reactions to extract precious metals from alloys. Its recovery rate is high, but the process is complicated, uses a large amount of chemicals, and produces harmful wastewater. Pyrometallurgy separates precious metals from other metals through high-temperature smelting. It is suitable for large-scale recycling and has a fast processing speed, but it has high energy consumption and high equipment costs, and is prone to produce harmful gases. Therefore, a new method for recycling precious metals is urgently needed to solve the problem of scarce precious metal resources in my country. Summary of the invention
[0005] In view of this, some embodiments disclose a method for recovering precious metals from waste precious metal alloys, comprising:
[0006] The waste precious metal alloy is used as an anode, and the inert metal electrode is used as a cathode to form an electrolysis system with a molten salt electrolyte; wherein the waste precious metal alloy is composed of precious metals and other metals, and the precious metal is gold or silver;
[0007] Set the electrolysis conditions to perform constant current electrolysis, and switch to constant voltage electrolysis when the electrolysis voltage reaches the upper limit;
[0008] During the electrolysis process, other metals at the anode undergo an oxidation reaction to generate ions that enter the molten salt electrolyte and then migrate to the cathode where they are reduced and precipitated; the precious metals at the anode do not participate in the electrode reaction, forming a porous precious metal.
[0009] Some embodiments disclose a method for recovering precious metals from waste precious metal alloys, wherein the waste precious metal alloy is a gold-copper alloy, a gold-chromium alloy, a gold-titanium alloy, a gold-zirconium alloy or a silver-copper alloy.
[0010] In the method for recovering precious metals from waste precious metal alloys disclosed in some embodiments, the gold content in the gold-copper alloy is 58.5%.
[0011] In the method for recovering precious metals from waste precious metal alloys disclosed in some embodiments, the gold content in the gold-chromium alloy is above 50%.
[0012] In the method for recovering precious metals from waste precious metal alloys disclosed in some embodiments, the gold content in the gold-titanium alloy is 60-90%.
[0013] In the method for recovering precious metals from waste precious metal alloys disclosed in some embodiments, the gold content in the gold-zirconium alloy is 50-90%.
[0014] In the method for recovering precious metals from waste precious metal alloys disclosed in some embodiments, the gold content in the silver-copper alloy is 20-90%.
[0015] In the method for recovering precious metals from waste precious metal alloys disclosed in some embodiments, the inert metal electrode is a stainless steel rod or a titanium rod.
[0016] In the method for recovering precious metals from waste precious metal alloys disclosed in some embodiments, the molten salt electrolyte includes one or more of LiCl, NaCl, KCl, LiF, NaF, and KF.
[0017] In some embodiments of the method for recovering precious metals from waste precious metal alloys, the electrolysis temperature of the electrolysis system is 400-900°C, the electrolysis time of the electrolysis system is 4-12 hours, and the current density of the electrolysis system is 0.01-2A·cm -2 The upper limit of the electrolysis voltage of the electrolysis system is 2.5~3V.
[0018] The method for recovering precious metals from waste precious metal alloys disclosed in the embodiment of the present invention uses the waste precious metal alloy as an anode and an inert metal electrode as a cathode to recover precious metals by molten salt electrolysis, wherein other metals in the waste precious metal alloy are dissolved, reduced and deposited on the cathode, and the precious metals in the waste precious metal alloy do not participate in the reaction and remain on the anode, thereby achieving separation of precious metals from other metals. The method for recovering precious metals from waste precious metal alloys disclosed in the embodiment of the present invention has a safe and simple process, low cost, and the recovered precious metals have high purity and low loss. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Schematic diagram of electrolysis for recovering precious metals from waste precious metal alloys. DETAILED DESCRIPTION
[0020] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.
[0021] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.
[0022] The terms "substantially" and "approximately" used herein are used to describe small fluctuations. For example, they can refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. The numerical data represented or presented in the range format herein are used only for convenience and brevity, and should therefore be flexibly interpreted as including not only the values clearly listed as the limits of the range, but also all independent values or sub-ranges contained in the range. For example, the numerical range of "1-5%" should be interpreted as including not only the clearly listed values of 1% to 5%, but also the independent values and sub-ranges within the range shown. Therefore, independent values such as 2%, 3.5% and 4% and sub-ranges such as 1%-3%, 2%-4% and 3%-5% are included in this numerical range. This principle also applies to the range of only one numerical value. In addition, such an interpretation applies regardless of the width of the range or the characteristics described.
[0023] In this document, including in the claims, transitional words such as "comprises," "includes," "with," "having," "containing," "involving," "accommodating," etc. are understood to be open-ended, i.e., meaning "including but not limited to." Only the transitional words "consisting of" and "composed of" are closed transitional words.
[0024] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.
[0025] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be arbitrarily combined, and the obtained technical solutions belong to the contents disclosed in the embodiments of the present application. It should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like mentioned in the present application indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the technical features and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention, unless it conflicts with the context. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance, unless it conflicts with the context.
[0026] In some embodiments, a method for recovering precious metals from waste precious metal alloys comprises:
[0027] like Figure 1 As shown, the waste precious metal alloy is used as an anode, and the inert metal electrode is used as a cathode to form an electrolysis system with a molten salt electrolyte; wherein the waste precious metal alloy is composed of precious metals and other metals, and the precious metal is gold or silver;
[0028] Set the electrolysis conditions to perform constant current electrolysis. When the electrolysis voltage reaches the upper limit, switch to constant voltage electrolysis to avoid dissolution of the precious metal on the anode.
[0029] During the electrolysis process, other metals in the anode are more active and undergo oxidation reactions to generate ions that enter the molten salt electrolyte and then migrate to the cathode where they are reduced and precipitated. The precious metals in the anode do not participate in the electrode reaction, forming a porous precious metal.
[0030] In some embodiments, the scrap precious metal alloy is a gold-copper alloy, a gold-chromium alloy, a gold-titanium alloy, a gold-zirconium alloy, or a silver-copper alloy.
[0031] In some embodiments, the gold content of the gold-copper alloy is 58.5%.
[0032] In some embodiments, the gold content in the gold-chromium alloy is greater than 50%.
[0033] In some embodiments, the gold content in the gold-titanium alloy is 60-90%.
[0034] In some embodiments, the gold content of the gold-zirconium alloy is 50-90%.
[0035] In some embodiments, the gold content in the silver-copper alloy is 20-90%.
[0036] In some embodiments, the inert metal electrode is a stainless steel rod or a titanium rod.
[0037] In some embodiments, the molten salt electrolyte includes one or more of LiCl, NaCl, KCl, LiF, NaF, KF.
[0038] In some embodiments, the molten salt electrolyte is LiCl-KCl, and the mass ratio of LiCl to KCl is 45:55.
[0039] In some embodiments, the molten salt electrolyte is NaCl-KCl, and the mass ratio of NaCl to KCl is 44:56.
[0040] In some embodiments, the electrolysis temperature of the electrolysis system is 400-900° C., the electrolysis time of the electrolysis system is 4-12 h, and the current density of the electrolysis system is 0.01-2 A·cm -2 The upper limit of the electrolysis voltage of the electrolysis system is 2.5~3V.
[0041] Generally, the current density can be determined according to the content and type of the precious metal in the precious metal alloy. If the content of the precious metal in the alloy is low, a larger current density is required for electrolysis so that all the impurity metals are dissolved and the precious metals remaining at the anode are not dissolved; if the content of the precious metal in the alloy is high, a smaller current density is selected for electrolysis, because a larger current density will dissolve the precious metals remaining at the anode, causing the precious metals and impurities to precipitate together, and the purpose of refining cannot be achieved. Therefore, in the embodiment of the present invention, if the precious metal content is less than 50%, a larger current density is selected; if the precious metal content is more than 50%, a smaller current density is selected.
[0042] Generally, setting an upper limit for the electrolysis voltage can ensure the efficiency of the precious metal recovery process and the high purity of the recovered precious metals; at the same time, side reactions can be avoided. If the voltage exceeds a certain critical value, other ions in the electrolyte may undergo reduction or oxidation reactions, resulting in side reactions and affecting purity. Excessively high voltage can also cause system instability and affect the uniformity of metal deposition. During the electrolysis process, some precious metals have a potential close to that of impurities, and the precipitation of impurities needs to be controlled by controlling the electrolysis voltage.
[0043] The standard reduction potential of gold is about +1.69V, the standard reduction potential of silver is about +0.8V, the standard reduction potential of copper is about +0.34V, the standard reduction potential of chromium is about +1.33V at most, the standard reduction potential of titanium is about +0.31V at most, and the standard reduction potential of zirconium is about -1.53V. This means that in the embodiments of the present invention, the precious metal in the precious metal alloy is more difficult to oxidize or more easily reduced than other alloys in the precious metal alloy. Setting the upper limit of the electrolysis voltage to 2.5-3V can effectively precipitate other metals in the precious metal alloy from the solution, and minimize the dissolution of the precious metal and avoid unnecessary side reactions.
[0044] The technical details are further illustrated below in conjunction with embodiments.
[0045] Example 1
[0046] Example 1 discloses a method for recovering gold from a gold-copper alloy, comprising:
[0047] like Figure 1 As shown, a gold-copper alloy is used as an anode, a stainless steel rod is used as a cathode, and an electrolysis system is formed with a LiCl-KCl electrolyte;
[0048] The electrolysis temperature was set to 500 °C and the current density was set to 1.8 A cm -2 , perform constant current electrolysis; when the electrolysis voltage reaches 2.8V, switch to constant voltage electrolysis;
[0049] During the electrolysis process, copper undergoes an oxidation reaction to generate ions that enter the molten salt electrolyte and then migrate to the cathode where they are reduced and precipitated; gold does not participate in the electrode reaction, forming porous gold.
[0050] After 10 hours of electrolysis, the anode and cathode deposited products were weighed and tested for purity. The results showed that the mass of copper deposited at the cathode was almost consistent with the loss at the anode, and the purity of gold on the anode was about 96.7%.
[0051] Example 2
[0052] Example 2 discloses a method for recovering gold from a gold-chromium alloy, comprising:
[0053] The gold-chromium alloy was used as the anode, the stainless steel rod was used as the cathode, and the NaCl-KCl electrolyte formed an electrolysis system;
[0054] The electrolysis temperature was set to 750 °C and the current density was set to 1.5 A cm -2 , perform constant current electrolysis; when the electrolysis voltage reaches 2.8V, switch to constant voltage electrolysis;
[0055] During the electrolysis process, chromium undergoes an oxidation reaction to generate ions that enter the molten salt electrolyte and then migrate to the cathode where they are reduced and precipitated; gold does not participate in the electrode reaction, forming porous gold.
[0056] After 12 hours of electrolysis, the anode and cathode deposited products were weighed and tested for purity. The results showed that the mass of chromium deposited at the cathode was almost consistent with the loss at the anode, and the purity of gold on the anode was about 98.3%.
[0057] The method for recovering precious metals from waste precious metal alloys disclosed in the embodiment of the present invention uses the waste precious metal alloy as an anode and an inert metal electrode as a cathode to recover precious metals by molten salt electrolysis, wherein other metals in the waste precious metal alloy are dissolved, reduced and deposited on the cathode, and the precious metals in the waste precious metal alloy do not participate in the reaction and remain on the anode, thereby achieving separation of precious metals from other metals. The method for recovering precious metals from waste precious metal alloys disclosed in the embodiment of the present invention has a safe and simple process, low cost, and the recovered precious metals have high purity and low loss.
[0058] The technical solutions disclosed in the present invention and the technical details disclosed in the embodiments are merely illustrative of the inventive concept of the present invention and do not constitute a limitation on the technical solutions of the present invention. Any conventional changes, substitutions or combinations of the technical details disclosed in the embodiments of the present invention have the same inventive concept as the present invention and are within the protection scope of the claims of the present invention.
Claims
1. A method for recovering precious metals from waste precious metal alloys, characterized in that: include: The waste precious metal alloy is used as an anode, and the inert metal electrode is used as a cathode to form an electrolysis system with a molten salt electrolyte; wherein the waste precious metal alloy is composed of precious metals and other metals, and the precious metal is gold or silver; Set the electrolysis conditions to perform constant current electrolysis, and switch to constant voltage electrolysis when the electrolysis voltage reaches the upper limit; During the electrolysis process, other metals at the anode undergo an oxidation reaction to generate ions that enter the molten salt electrolyte and then migrate to the cathode where they are reduced and precipitated; the precious metals at the anode do not participate in the electrode reaction, forming a porous precious metal.
2. The method for recovering precious metals from waste precious metal alloys according to claim 1, characterized in that: The waste precious metal alloy is a gold-copper alloy, a gold-chromium alloy, a gold-titanium alloy, a gold-zirconium alloy or a silver-copper alloy.
3. The method for recovering precious metals from waste precious metal alloys according to claim 2, characterized in that: The gold content in the gold-copper alloy is 58.5%.
4. The method for recovering precious metals from waste precious metal alloys according to claim 2, characterized in that: The gold content in the gold-chromium alloy is more than 50%.
5. The method for recovering precious metals from waste precious metal alloys according to claim 2, characterized in that: The gold content in the gold-titanium alloy is 60-90%.
6. The method for recovering precious metals from waste precious metal alloys according to claim 2, characterized in that: The gold content of the gold-zirconium alloy is 50-90%.
7. The method for recovering precious metals from waste precious metal alloys according to claim 2, characterized in that: The gold content in the silver-copper alloy is 20-90%.
8. The method for recovering precious metals from waste precious metal alloys according to claim 1, characterized in that: The inert metal electrode is a stainless steel rod or a titanium rod.
9. The method for recovering precious metals from waste precious metal alloys according to claim 1, characterized in that: The molten salt electrolyte includes one or more of LiCl, NaCl, KCl, LiF, NaF, and KF.
10. The method for recovering precious metals from waste precious metal alloys according to claim 1, characterized in that: The electrolysis temperature of the electrolysis system is 400-900° C., the electrolysis time of the electrolysis system is 4-12 hours, and the current density of the electrolysis system is 0.01-2 A·cm -2 The upper limit of the electrolysis voltage of the electrolysis system is 2.5 to 3V.