Method for preparing cyanide-free gold-plating solution gold sodium sulfite

Abstract

The invention belongs to the technical field of precious metal compound preparation, and particularly relates to a method for preparing cyanide-free gold plating solution gold sodium sulfite. A mixed solution of sodium sulfite and sodium chloride is used as anolyte, a sodium hydroxide solution is used as catholyte, and sodium sulfite in the anolyte is used as a complexing agent of gold ions and cooperates with sodium chloride to promote anode dissolution. According to the method, the toxicity risk of a traditional cyanide method is avoided, the reaction condition is mild, the product purity is high, no nitric oxide is generated in the process, no dangerous thanic acid gold intermediate is generated in the process, chloride ions can be effectively reduced, and a green and environment-friendly product can be produced.

Description

Technical Field

[0001] This invention belongs to the field of precious metal compound preparation technology, and more specifically relates to a method for preparing cyanide-free gold plating solution sodium gold sulfite. Background Technology

[0002] Currently, commonly used gold plating processes both domestically and internationally typically employ cyanide-containing electrolytes to deposit gold. While cyanide effectively dissolves gold and provides a stable plating process, it is highly toxic and poses risks to the environment and the health of operators.

[0003] Cyanide-free gold plating uses chemical formulations that replace cyanide, typically employing cyanide-free organic compounds or other metal salts. This ensures the quality of the metal coating while reducing environmental pollution and operational hazards. This technology is widely used in electronics and semiconductors, jewelry, and other high-end manufacturing industries, and is particularly suitable for applications with high environmental protection requirements. Therefore, the development of cyanide-free gold plating processes will drive its gradual replacement of traditional cyanide gold plating processes.

[0004] The traditional method for producing sodium gold sulfite is the conventional chemical method, which can be divided into three categories:

[0005] (1) Aqua regia dissolution of gold complexation method: First, gold is dissolved in aqua regia to generate chloroauric acid, and then an appropriate amount of sodium sulfite solution is added for complexation. However, this process requires a large amount of hydrochloric acid and nitric acid, which not only results in a long process flow, high raw material consumption, serious environmental pollution, and high production costs, but also makes it difficult to separate by-products such as sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate, leading to low product purity;

[0006] (2) Gold hydroxide complexation method: This method utilizes the reaction of chloroauric acid with sodium hydroxide to precipitate gold hydroxide under alkaline conditions, and then complexes the gold hydroxide with sodium sulfite to form sodium gold sulfite. However, this method has a low gold hydroxide yield, only about 60%.

[0007] (3) Gold fulminate reaction method: Chloroauric acid is first reacted with ammonia to form gold fulminate precipitate. The precipitate is then mixed with water to form a slurry, which is then reacted with sodium sulfite to form sodium gold sulfite. However, fulminate metal is an explosive trivalent gold salt, posing a significant safety hazard. Therefore, the development of a green and safe process for preparing sodium gold sulfite is urgently needed.

[0008] In recent years, diaphragm electrolysis has been successfully applied in fields such as chemical engineering, environmental protection, non-ferrous metallurgy, and the preparation of precious metal products. In the gold plating industry, electrolysis has also been successfully used to prepare potassium gold cyanide and sodium cyanide. However, this method is difficult to transfer to the preparation of sodium gold sulfite. This is mainly because cyanide ions are highly stable and are excellent ligands for gold, while sodium sulfite has strong reducing properties, poor chemical stability, and weak coordination ability with gold. During electrolytic preparation, it easily undergoes redox reactions with gold ions, leading to preparation failure. Therefore, the electrolytic preparation of sodium gold sulfite presents certain challenges.

[0009] In summary, existing methods for producing sodium gold sulfite have two major drawbacks: First, traditional chemical methods for preparing sodium gold sulfite involve long processes, high raw material consumption, and severe environmental pollution. Furthermore, the difficulty in separating byproducts leads to low product purity, and some methods also suffer from low yields or safety hazards. Second, although the membrane electrolysis method has applications in related fields, it is difficult to directly apply it to the preparation of sodium gold sulfite due to the poor chemical stability of sodium sulfite and its weak coordination ability with gold. Summary of the Invention

[0010] This invention provides a method for preparing cyanide-free gold plating solution sodium gold sulfite. By optimizing the electrolyte formulation, the method improves electrolysis efficiency and product purity, reduces production costs, and achieves environmentally friendly production.

[0011] This invention provides a method for preparing a cyanide-free gold plating solution, sodium gold sulfite, comprising:

[0012] Gold ingots with a purity of 99.99% are rolled into gold bars with a thickness of 2mm. The gold bars are then cut according to a set ratio to obtain cut gold bars.

[0013] The cut gold bar was cleaned sequentially with 25% ethanol and plasma water, and the cleaned cut gold bar was placed in the anode area of ​​the diaphragm electrolysis device. The anode area of ​​the diaphragm electrolysis device contained 100 ml of anolyte prepared by mixing sodium sulfite, sodium chloride and deionized water, and the cathode area contained 100 ml of sodium hydroxide solution and titanium sheet.

[0014] After the diaphragm electrode device is connected to a power source and undergoes electrolysis for a set time, the reaction solution in the anode region is subjected to reduced pressure evaporation, cooling filtration, and vacuum drying to obtain sodium gold sulfite.

[0015] Preferably, the step of cutting the block gold bar according to a set ratio to obtain cut gold bars specifically includes:

[0016] The block gold bar is cut according to a set ratio to obtain a cut gold bar of 40mm*60mm*12mm;

[0017] Alternatively, the block gold bar can be cut according to a set ratio to obtain a 60mm*160mm*10mm cut gold bar.

[0018] Preferably, the concentration of sodium sulfite is 0.5-2 mol / L, the mass percentage of sodium chloride is 5 wt%-15 wt%, and the concentration of sodium hydroxide solution is 0.5-2 mol / L.

[0019] Preferably, after the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, it specifically includes:

[0020] The diaphragm electrode device is connected to an AC power source and the electrode reaction time is 1-4 hours, wherein the electrolysis current is 0.2-1.0A.

[0021] Preferably, the diaphragm electrode device is connected to a power source to perform an electrolytic reaction according to a set time, and further includes:

[0022] A stabilizing complexing agent is added to the electrolyte, wherein the mass ratio of the stabilizing complexing agent to the cut gold bar is 1:3;

[0023] The stabilizing complexing agent is any one of dipotassium hydrogen phosphate, ethylenediamine, or disodium ethylenediaminetetraacetate.

[0024] Preferably, the step of subjecting the reaction solution in the anode region to reduced pressure evaporation, cooling filtration, and vacuum drying to obtain sodium gold sulfite specifically includes:

[0025] The reaction solution in the anode region is collected and evaporated under reduced pressure in a rotary evaporator at a temperature of 50-60℃ for 5 hours to obtain a reaction solution containing crystals.

[0026] The reaction solution containing crystals was placed in an ice-water bath for cooling and filtration.

[0027] The cooled and filtered reaction solution was placed in a vacuum chamber at a temperature of 50-60℃ and dried under vacuum for 12 hours to obtain the sodium gold sulfite.

[0028] In summary, this invention provides a method for preparing a cyanide-free gold plating solution, sodium gold sulfite, comprising: rolling a gold ingot with a purity of 99.99% into a 2mm thick block gold bar; cutting the block gold bar according to a set ratio to obtain cut gold bars; cleaning the cut gold bars sequentially with 25% ethanol and plasma water; placing the cleaned cut gold bars in the anode region of a diaphragm electrolysis device; wherein, the anode region of the diaphragm electrolysis device contains 100ml of an anolyte prepared by mixing sodium sulfite, sodium chloride, and deionized water, and the cathode region contains 100ml of sodium hydroxide solution and a titanium sheet; after the diaphragm electrode device is connected to a power source and electrolyzes for a set time, the reaction solution in the anode region is subjected to reduced pressure evaporation, cooling filtration, and vacuum drying to obtain sodium gold sulfite. This method is simple and efficient. By optimizing the electrolyte formulation and combining it with membrane electrolysis technology, the preparation process is shortened and production costs are reduced. Furthermore, the product obtained by this method has high purity. The separation of the anode and cathode regions by the cation exchange membrane reduces the occurrence of side reactions, and the addition of a stabilizing complexing agent further improves the purity of the product. In addition, this method is environmentally friendly and safe. The preparation process does not require the use of highly toxic cyanide, reduces the consumption of reagents such as hydrochloric acid and nitric acid, and reduces the harm to the environment and operators. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides a method for preparing a cyanide-free gold plating solution of sodium gold sulfite, the method comprising the following steps:

[0031] Step 101: Roll the gold ingot with a purity of 99.99% into a block gold bar with a thickness of 2mm, and cut the block gold bar according to the set ratio to obtain cut gold bars;

[0032] Step 102: The cut gold bar is cleaned sequentially with 25% ethanol and plasma water, and the cleaned cut gold bar is placed in the anode area of ​​the diaphragm electrolysis device; wherein, 100 ml of anolyte prepared by mixing sodium sulfite, sodium chloride and deionized water is placed in the anode area of ​​the diaphragm electrolysis device, and 100 ml of sodium hydroxide solution and titanium sheet are placed in the cathode area.

[0033] Step 103: After the diaphragm electrode device is connected to a power source and undergoes electrolysis for a set time, the reaction solution in the anode region is subjected to reduced pressure evaporation, cooling filtration, and vacuum drying to obtain sodium gold sulfite.

[0034] In step 101, a gold ingot with a purity of 99.99% is placed in a pressing machine and crushed to obtain a 2mm thick gold bar. Further, the gold bar is cut according to a set ratio to obtain cut gold bars. In this embodiment of the invention, the gold bar can be cut according to a set ratio to obtain cut gold bars with dimensions of 40mm*60mm*12mm; alternatively, cut gold bars with dimensions of 60mm*160mm*10mm can also be obtained. In practical applications, the specific dimensions of the cut gold bars are not limited.

[0035] In step 102, the cut gold bar is cleaned. Specifically, the cut gold bar is first cleaned with 25% ethanol to remove oil stains, and then cleaned with deionized water to obtain a clean cut gold bar.

[0036] Furthermore, the clean, cut gold bars are placed in the anode area of ​​the diaphragm electrolysis device, ready for the electrolysis reaction.

[0037] In this embodiment of the invention, before the cut gold bar is placed in the anode area of ​​the diaphragm electrolysis device, a solution needs to be placed in the anode and cathode areas of the diaphragm electrolysis device.

[0038] The membrane electrolysis device provided in this embodiment of the invention includes an anode region, a cathode region, and a cation exchange membrane for separating the anode region and the cathode region. 100 ml of an anolyte, prepared by mixing sodium sulfite, sodium chloride, and deionized water, is added to the anode region, wherein the concentration of sodium sulfite is 0.5-2 mol / L, and the mass percentage of sodium chloride is 5 wt%-15 wt%. Furthermore, 100 ml of sodium hydroxide solution and a titanium sheet are placed in the cathode region, wherein the concentration of the sodium hydroxide solution is 0.5-2 mol / L.

[0039] In step 103, after the diaphragm electrode device is connected to the power supply and undergoes an electrolytic reaction for a set time, the electrode reaction time of the diaphragm electrode device connected to the AC power supply is 1-4 hours and the electrolytic current is 0.2-1.0A.

[0040] Further, a stabilizing complexing agent was added to the reaction solution obtained from the anode region, and then the reaction solution from the anode region was collected. The reaction solution was evaporated under reduced pressure in a rotary evaporator at a temperature of 50-60℃ for 5 hours to obtain a reaction solution containing crystals. The reaction solution containing crystals was placed in an ice-water bath for cooling and filtration. The cooled and filtered reaction solution was placed in a vacuum chamber at a temperature of 50-60℃ for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0041] It should be noted that the stabilizing complexing agent added to the reaction solution in the anolyte has a mass ratio of 1:3 to the cut gold bar. The stabilizing complexing agent can be dipotassium hydrogen phosphate, ethylenediamine, or disodium ethylenediaminetetraacetate. In this embodiment of the invention, the specific composition of the stabilizing complexing agent is not limited.

[0042] To more clearly illustrate the method for recycling silver electrodes from waste crystalline silicon photovoltaic modules provided by the embodiments of the present invention, several embodiments related to this method are described below.

[0043] Example 1

[0044] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 40mm*60mm*12mm.

[0045] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0046] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0047] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0048] Au + +2Cl - →(AuCl2) -

[0049]

[0050] Further, prepare the anolyte: Weigh 6.3g of sodium sulfite and 5.0g of sodium chloride, dissolve them in 100ml of deionized water to obtain the anolyte, and then place the anolyte in the anode area. The concentration of sodium sulfite in the anolyte is 0.5mol / L, and the mass percentage of sodium chloride is 5wt%.

[0051] Preparation of cathodic solution: Weigh 2.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 0.5mol / L. Then place the sodium hydroxide solution in the cathode area.

[0052] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0053] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.2A and the electrolytic reaction time is 1 hour. After the electrolytic reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 50°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 50°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0054] Example 2

[0055] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0056] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0057] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0058] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0059] Au + +2Cl - →(AuCl2) -

[0060]

[0061] Further, prepare the anolyte: Weigh 12.6 g of sodium sulfite and 5.0 g of sodium chloride, dissolve them in 100 ml of deionized water to obtain the anolyte, and then place the anolyte in the anode area. The concentration of sodium sulfite in the anolyte is 1.0 mol / L, and the mass percentage of sodium chloride is 5 wt%.

[0062] Preparation of cathodic solution: Weigh 2.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 0.5mol / L. Then place the sodium hydroxide solution in the cathode area.

[0063] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0064] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.2A and the electrolytic reaction time is 1 hour. After the electrolytic reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 60°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 60°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0065] Example 3

[0066] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 40mm*60mm*12mm.

[0067] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0068] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0069] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0070] Au + +2Cl - →(AuCl2) -

[0071]

[0072] Further, prepare the anolyte: Weigh 25.6 g of sodium sulfite and 5.0 g of sodium chloride, dissolve them in 100 ml of deionized water to obtain the anolyte, and then place the anolyte in the anode area. The concentration of sodium sulfite in the anolyte is 2 mol / L, and the mass percentage of sodium chloride is 5 wt%.

[0073] Preparation of cathodic solution: Weigh 2.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 0.5mol / L. Then place the sodium hydroxide solution in the cathode area.

[0074] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0075] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.2A and the electrolytic reaction time is 1 hour. After the electrolytic reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0076] Example 4

[0077] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0078] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0079] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0080] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0081] Au + +2Cl - →(AuCl2)-

[0082]

[0083] Further, the anolyte was prepared as follows: 6.3 g of sodium sulfite and 15.0 g of sodium chloride were weighed and dissolved in 100 ml of deionized water to obtain the anolyte. The anolyte was then placed in the anode zone. The concentration of sodium sulfite in the anolyte was 0.5 mol / L, and the mass percentage of sodium chloride was 15 wt%.

[0084] Preparation of cathodic solution: Weigh 2.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 0.5mol / L. Then place the sodium hydroxide solution in the cathode area.

[0085] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0086] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.2A and the electrolytic reaction time is 1 hour. After the electrolytic reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0087] Example 5

[0088] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0089] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0090] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0091] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0092] Au + +2Cl - →(AuCl2) -

[0093]

[0094] Further, prepare the anolyte: Weigh 6.3g of sodium sulfite and 10.0g of sodium chloride, dissolve them in 100ml of deionized water to obtain the anolyte, and then place the anolyte in the anode area. The concentration of sodium sulfite in the anolyte is 0.5mol / L, and the mass percentage of sodium chloride is 10wt%.

[0095] Preparation of cathodic solution: Weigh 2.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 0.5mol / L. Then place the sodium hydroxide solution in the cathode area.

[0096] The gold bar and titanium electrode are respectively placed in the anode and cathode areas.

[0097] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.2A and the electrolytic reaction time is 1 hour. After the electrolytic reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0098] Example 6

[0099] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0100] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0101] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0102] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0103] Au + +2Cl - →(AuCl2) -

[0104]

[0105] Further, the anolyte was prepared as follows: 6.3 g of sodium sulfite and 15.0 g of sodium chloride were weighed and dissolved in 100 ml of deionized water to obtain the anolyte. The anolyte was then placed in the anode zone. The concentration of sodium sulfite in the anolyte was 0.5 mol / L, and the mass percentage of sodium chloride was 15 wt%.

[0106] Preparation of cathodic solution: Weigh 8.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 2mol / L. Then place the sodium hydroxide solution in the cathode area.

[0107] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0108] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.2A and the electrolytic reaction time is 1 hour. After the electrolytic reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0109] Example 7

[0110] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 40mm*60mm*12mm.

[0111] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0112] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0113] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0114] Au + +2Cl - →(AuCl2) -

[0115]

[0116] Further, the anolyte was prepared as follows: 6.3 g of sodium sulfite and 15.0 g of sodium chloride were weighed and dissolved in 100 ml of deionized water to obtain the anolyte. The anolyte was then placed in the anode zone. The concentration of sodium sulfite in the anolyte was 0.5 mol / L, and the mass percentage of sodium chloride was 15 wt%.

[0117] Preparation of cathodic solution: Weigh 4.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 1mol / L. Then place the sodium hydroxide solution in the cathode area.

[0118] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0119] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.2A and the electrolytic reaction time is 1 hour. After the electrolytic reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0120] Example 8

[0121] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0122] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0123] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0124] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0125] Au + +2Cl - →(AuCl2) -

[0126]

[0127] Further, the anolyte was prepared as follows: 6.3 g of sodium sulfite and 15.0 g of sodium chloride were weighed and dissolved in 100 ml of deionized water to obtain the anolyte. The anolyte was then placed in the anode zone. The concentration of sodium sulfite in the anolyte was 0.5 mol / L, and the mass percentage of sodium chloride was 15 wt%.

[0128] Preparation of cathodic solution: Weigh 4.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 1mol / L. Then place the sodium hydroxide solution in the cathode area.

[0129] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0130] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.5A and the electrolytic reaction time is 1 hour. After the electrolytic reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0131] Example 9

[0132] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0133] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0134] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0135] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0136] Au + +2Cl - →(AuCl2) -

[0137]

[0138] Further, the anolyte was prepared as follows: 6.3 g of sodium sulfite and 15.0 g of sodium chloride were weighed and dissolved in 100 ml of deionized water to obtain the anolyte. The anolyte was then placed in the anode zone. The concentration of sodium sulfite in the anolyte was 0.5 mol / L, and the mass percentage of sodium chloride was 15 wt%.

[0139] Preparation of cathodic solution: Weigh 4.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 1mol / L. Then place the sodium hydroxide solution in the cathode area.

[0140] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0141] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolysis reaction for a set time, wherein the current is 1.0 A and the electrolysis reaction time is 1 hour. After the electrolysis reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0142] Example 10

[0143] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0144] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0145] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0146] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0147] Au + +2Cl - →(AuCl2) -

[0148]

[0149] Further, the anolyte was prepared as follows: 6.3 g of sodium sulfite and 15.0 g of sodium chloride were weighed and dissolved in 100 ml of deionized water to obtain the anolyte. The anolyte was then placed in the anode zone. The concentration of sodium sulfite in the anolyte was 0.5 mol / L, and the mass percentage of sodium chloride was 15 wt%.

[0150] Preparation of cathodic solution: Weigh 4.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 1mol / L. Then place the sodium hydroxide solution in the cathode area.

[0151] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0152] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolysis reaction for a set time, wherein the current is 0.5A and the electrolysis reaction time is 2 hours. After the electrolysis reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode area; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0153] Example 11

[0154] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0155] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0156] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0157] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0158] Au + +2Cl - →(AuCl2) -

[0159]

[0160] Further, the anolyte was prepared as follows: 6.3 g of sodium sulfite and 15.0 g of sodium chloride were weighed and dissolved in 100 ml of deionized water to obtain the anolyte. The anolyte was then placed in the anode zone. The concentration of sodium sulfite in the anolyte was 0.5 mol / L, and the mass percentage of sodium chloride was 15 wt%.

[0161] Preparation of cathodic solution: Weigh 4.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 1mol / L. Then place the sodium hydroxide solution in the cathode area.

[0162] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0163] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.5A and the electrolytic reaction time is 4 hours. After the electrolytic reaction is completed, 1.0 g of disodium ethylenediaminetetraacetate is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0164] Example 12

[0165] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0166] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0167] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0168] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0169] Au + +2Cl - →(AuCl2) -

[0170]

[0171] Further, the anolyte was prepared as follows: 6.3 g of sodium sulfite and 15.0 g of sodium chloride were weighed and dissolved in 100 ml of deionized water to obtain the anolyte. The anolyte was then placed in the anode zone. The concentration of sodium sulfite in the anolyte was 0.5 mol / L, and the mass percentage of sodium chloride was 15 wt%.

[0172] Preparation of cathodic solution: Weigh 4.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 1mol / L. Then place the sodium hydroxide solution in the cathode area.

[0173] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0174] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolysis reaction for a set time, wherein the current is 0.5A and the electrolysis reaction time is 1 hour. After the electrolysis reaction is completed, 1.0 g of dipotassium hydrogen phosphate is added to the reaction solution obtained in the anode area; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0175] Example 13

[0176] In step 101 above, a gold ingot with a purity of 99.99% can be rolled into a 2mm thick block gold bar using a tablet press. Then, the block gold bar is cut according to a set ratio to obtain a cut gold bar with a size of 60mm*160mm*10mm.

[0177] In step 102, a membrane electrolytic cell is first prepared. The electrolytic cell is divided into an anode area and a cathode area using a cation exchange membrane. Cut gold bars are set in the anode area, and titanium electrodes are set in the cathode area.

[0178] In this embodiment of the invention, the main reaction process of the membrane electrolysis method is as follows:

[0179] 2Au+4Na2SO3+2H2O→2Na3Au(SO3)2+2NaOH+H2↑

[0180] Au + +2Cl - →(AuCl2) -

[0181]

[0182] Further, the anolyte was prepared as follows: 6.3 g of sodium sulfite and 15.0 g of sodium chloride were weighed and dissolved in 100 ml of deionized water to obtain the anolyte. The anolyte was then placed in the anode zone. The concentration of sodium sulfite in the anolyte was 0.5 mol / L, and the mass percentage of sodium chloride was 15 wt%.

[0183] Preparation of cathodic solution: Weigh 4.0g of sodium hydroxide and dissolve it in 100ml of deionized water to obtain a sodium hydroxide solution with a concentration of 1mol / L. Then place the sodium hydroxide solution in the cathode area.

[0184] The gold bar cutting and titanium electrodes are respectively placed in the anode and cathode areas.

[0185] In step 103, the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction for a set time, wherein the current is 0.5A and the electrolytic reaction time is 1 hour. After the electrolytic reaction is completed, 1.0 g of ethylenediamine is added to the reaction solution obtained in the anode region; then the reaction solution is evaporated under reduced pressure in a rotary evaporator at 55°C for 5 hours to obtain a reaction solution containing crystals; the reaction solution containing crystals is placed in an ice-water bath for cooling and filtration; the cooled and filtered reaction solution is placed in a vacuum chamber at 55°C for vacuum drying for 12 hours to obtain sodium gold sulfite.

[0186] In summary, the present invention provides a method for preparing a cyanide-free gold plating solution, sodium gold sulfite, comprising: rolling a gold ingot with a purity of 99.99% into a 2mm thick block gold bar; cutting the block gold bar according to a set ratio to obtain cut gold bars; cleaning the cut gold bars sequentially with 25% ethanol and plasma water; placing the cleaned cut gold bars in the anode region of a diaphragm electrolysis device; wherein, the anode region of the diaphragm electrolysis device contains 100ml of an anolyte prepared by mixing sodium sulfite, sodium chloride, and deionized water, and the cathode region contains 100ml of sodium hydroxide solution and a titanium sheet; after the diaphragm electrode device is connected to a power source and electrolyzes for a set time, the reaction solution in the anode region is subjected to reduced pressure evaporation, cooling filtration, and vacuum drying to obtain sodium gold sulfite. This method uses 99.99% pure gold bars directly as the anode material (without requiring complex pretreatment steps such as dissolving in aqua regia), which can reduce the multiple chemical reaction steps in traditional chemical methods and shorten the preparation process. The anolyte only needs to be prepared by mixing sodium sulfite, sodium chloride, and deionized water, and the cathode liquid is a simple sodium hydroxide solution. The raw materials are few in number and easy to prepare, reducing the cost of raw material procurement and preparation. The electrolysis process parameters are controllable, the operation process is standardized, and there is no need for complex process control, thus improving production efficiency.

[0187] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a cyanide-free gold plating solution of sodium gold sulfite, characterized in that, include: Gold ingots with a purity of 99.99% are rolled into gold bars with a thickness of 2mm. The gold bars are then cut according to a set ratio to obtain cut gold bars. The cut gold bar was cleaned sequentially with 25% ethanol and plasma water, and the cleaned cut gold bar was placed in the anode area of ​​the diaphragm electrolysis device. The anode area of ​​the diaphragm electrolysis device contained 100 ml of anolyte prepared by mixing sodium sulfite, sodium chloride and deionized water, and the cathode area contained 100 ml of sodium hydroxide solution and titanium sheet. After the diaphragm electrode device is connected to a power source and undergoes electrolysis for a set time, the reaction solution in the anode region is subjected to reduced pressure evaporation, cooling filtration, and vacuum drying to obtain sodium gold sulfite.

2. The method as described in claim 1, characterized in that, The step of cutting the block gold bar according to a set ratio to obtain cut gold bars specifically includes: The block gold bar is cut according to a set ratio to obtain a cut gold bar of 40mm*60mm*12mm; Alternatively, the block gold bar can be cut according to a set ratio to obtain a 60mm*160mm*10mm cut gold bar.

3. The method as described in claim 1, characterized in that, The concentration of sodium sulfite is 0.5-2 mol / L, the mass percentage of sodium chloride is 5 wt%-15 wt%, and the concentration of sodium hydroxide solution is 0.5-2 mol / L.

4. The method as described in claim 1, characterized in that, After the diaphragm electrode device is connected to a power source and undergoes an electrolytic reaction according to a set time, the specific process includes: The diaphragm electrode device is connected to an AC power source and the electrode reaction time is 1-4 hours, wherein the electrolysis current is 0.2-1.0A.

5. The method as described in claim 1, characterized in that, The diaphragm electrode device is connected to a power source to perform an electrolytic reaction according to a set time, and also includes: A stabilizing complexing agent is added to the electrolyte, wherein the mass ratio of the stabilizing complexing agent to the cut gold bar is 1:3; The stabilizing complexing agent is any one of dipotassium hydrogen phosphate, ethylenediamine, or disodium ethylenediaminetetraacetate.

6. The method as described in claim 1, characterized in that, The process of reducing pressure evaporation, cooling filtration, and vacuum drying of the reaction solution in the anode region to obtain sodium gold sulfite specifically includes: The reaction solution in the anode region is collected and evaporated under reduced pressure in a rotary evaporator at a temperature of 50-60℃ for 5 hours to obtain a reaction solution containing crystals. The reaction solution containing crystals was placed in an ice-water bath for cooling and filtration. The cooled and filtered reaction solution was placed in a vacuum chamber at a temperature of 50-60℃ and dried under vacuum for 12 hours to obtain the sodium gold sulfite.

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