CN112301388A - Cyanide-free electroplating process - Google Patents
Cyanide-free electroplating process Download PDFInfo
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- CN112301388A CN112301388A CN201910674514.8A CN201910674514A CN112301388A CN 112301388 A CN112301388 A CN 112301388A CN 201910674514 A CN201910674514 A CN 201910674514A CN 112301388 A CN112301388 A CN 112301388A
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/48—Electroplating: Baths therefor from solutions of gold
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- Electroplating And Plating Baths Therefor (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
The invention discloses a cyanide-free electroplating process suitable for electroplating the surface of gold ornaments, which is characterized in that gold pieces with the gold content of more than 99.999 percent are put into aqua regia to be dissolved, and then nitrate is removed to prepare gold water; transferring the gold water to a gold fulminate reaction kettle, and slowly adding ammonia water to prepare gold fulminate mud; adding the fulminate gold mud into a reaction kettle containing sodium sulfite under the stirring state, then adding sulfuric acid with the concentration of 5-8%, and obtaining a gold sodium sulfite solution with the gold content of 10-38 g/L after reaction; hanging the gold ornament to be electroformed on a specific bracket, removing surface dirt and impurities, placing the gold ornament in an electroplating tank filled with a gold sodium sulfite solution, controlling the temperature between 55 ℃ and 75 ℃ and the electroplating time between 0.5h and 3h, and obtaining the gold ornament with the surface gold content of more than 99.995%. The electroplating solution does not contain cyanide, so that the requirements of environmental protection production are met, and meanwhile, the gold ornament has the advantages of high surface purity, high brightness, high hardness, good toughness and wear resistance.
Description
Technical Field
The invention relates to a cyanide-free electroplating process, in particular to a gold plating process on the surface of a gold ornament.
Background
Along with the improvement of the living standard of people, the gold ornament is more and more favored by consumers. The purity (gold content) of the existing gold ornaments is generally 99%, in order to improve the surface purity and brightness, more and more gold ornaments adopt an electroplating process, the purity of the existing electroplated gold ornaments is generally 99.9%, and the surface purity and brightness are improved compared with those of common gold ornaments, but an electroplating solution adopted in the electroplating process is mainly a solution containing potassium cyanide. Because potassium cyanide belongs to the highly toxic substance, can cause harm to operator's health in the gold goods production process, simultaneously, the waste liquid that the production process produced still can cause environmental pollution, and the expense of handling the waste liquid is high.
Disclosure of Invention
The invention aims to solve the technical problem of providing a cyanide-free electroplating process which has low treatment cost of production waste liquid and is suitable for electroplating the surface of gold ornaments.
In order to solve the technical problem, the invention comprises the following steps:
1) dissolving gold tablet with gold content of 99.999% in aqua regia, and removing nitre to obtain gold solution;
2) transferring the gold water to a gold fulminate reaction kettle, and slowly adding ammonia water to prepare gold fulminate mud;
3) putting the gold fulminate mud into a reaction kettle containing sodium sulfite, adding the gold fulminate mud under the stirring state, then adding sulfuric acid with the concentration of 5% -8%, and obtaining a gold sodium sulfite solution with the gold content of 10-38 g/L after reaction;
4) hanging the gold ornaments to be electroformed on a specific bracket, and removing dirt and impurities on the surface;
5) placing the gold ornament to be electroformed in an electroplating tank filled with a gold sodium sulfite solution, wherein the temperature is between 55 and 75 ℃, and the electroplating time is 0.5 to 3 hours, thus obtaining the gold ornament with the surface gold content of more than 99.995 percent.
The step 1) comprises the following specific steps:
a. tabletting gold tablets: the width is 4.5 CM-5.5 CM, the thickness is 0.8 MM-1.2 MM;
b. putting the gold sheet into an ultrasonic cleaning machine, and cleaning for 2-5 minutes;
c. placing the mixture into an electric furnace with the temperature of 350-400 ℃ and baking for more than 15 minutes;
d. putting the cooled gold sheet into a reaction kettle for preparing gold water, firstly adding 1250 ml-1350 ml of nitric acid and 1250 ml-1350 ml of pure water into the reaction kettle for preparing the gold water, then adding 3750 ml-3850 ml of hydrochloric acid into the reaction kettle, and finally adding 2450 ml-2550 ml of hydrochloric acid into the reaction kettle in three to five times until the gold sheet is completely dissolved in the aqua regia;
e. and (3) heating the reaction kettle by using water vapor to keep the temperature of the reaction kettle between 90 and 100 ℃ for 40 to 50 minutes, and finishing nitrate removal when brown gas is not generated in the gold water any more.
The step 2) comprises the following specific steps:
a. keeping the temperature in the reaction kettle of the gold fulminate at 70-80 ℃, slowly adding 6500 ml-7500 ml of ammonia water, continuously stirring the reaction kettle, and reacting for half an hour to form slurry-shaped gold fulminate mud;
b. and (2) filtering and cleaning the leic acid gold mud by using a Buchner funnel, putting the cleaned leic acid gold mud into a leic acid gold reaction kettle, adding 1L-1.1L of distilled water, uniformly stirring, filtering and cleaning the leic acid gold mud by using the Buchner funnel, and repeatedly filtering and cleaning the leic acid gold mud for 8-10 times until the filtered water is neutral.
The step 3) comprises the following specific steps:
a. heating a reaction kettle to 70-80 ℃, adding 7700-7800 g of sodium sulfite into the gold sodium sulfite reaction kettle, adding 15-15.5L of hot water, and stirring for dissolving;
b. putting the leic acid gold mud into a sodium sulfite reaction kettle, and continuously stirring for 2-3 hours;
c. adding 5L-5.5L of sulfuric acid with the concentration of 5% -8% in two times, and reacting for more than 12 hours, wherein the interval between the two times is more than 5 minutes, and the pH value is kept between 9 and 11.
The step 4) comprises the following specific steps:
a. putting the hanging rack with the gold ornaments into a high-pressure cleaning water vat for cleaning for 30-60 seconds;
b. cleaning in an ultrasonic cleaning machine containing wax removing water for 30-60 seconds;
c. putting the mixture into a high-pressure cleaning water tank again for cleaning for 30-60 seconds;
d. putting the hanger with gold ornaments into an electrolytic degreasing cylinder, adjusting the voltage to 3-5 v and the current to 20-40A, and controlling the temperature in the cylinder to be 55-70 ℃ for 20-40 seconds;
e. and (3) putting the hanging rack with the gold ornaments into a washing water vat for washing for more than 3-4 times, then putting the hanging rack into a dilute sulphuric acid vat for pickling, and finally putting the hanging rack into the washing water vat for washing for 2 times.
In the step 5), the voltage in the electroplating cylinder is 3v-5v, the current is 20A-40A, the electroplating cylinder is adjusted in forward rotation and reverse rotation every 10 seconds, and the rotating speed is 11 m/min-14 m/min.
The process of the invention has the following advantages and effects:
1. because the electroplating solution does not contain cyanide, the operator body is not damaged in the production process, the treatment cost of the production waste liquid is low, and the treated production waste liquid does not cause environmental pollution;
2. the gold ornaments produced by the process have the following characteristics:
a. the gold ornaments have high purity, and because 99.999 percent of gold is used as a manufacturing raw material in the plating solution, the surface purity of the ornaments is more than 99.995 percent;
b. the brightness is high, the surface smoothness of the ornament is about 0.05, the ornament is more obvious under the same gram weight, and different wearing requirements can be met;
c. the hardness is high, the Mohs hardness of the surface of the ornament is about 4.0, and the ornament is not easy to deform;
d. the product has good toughness and wear resistance, is not easy to scratch on the surface, and can durably maintain the brand-new appearance of the product when being purchased;
e. the jewelry has high surface glossiness, and can be worn for a long time and become new.
Detailed Description
The cyanide-free electroplating process is implemented according to the following steps:
1) preparing gold water:
a. tabletting gold tablets with gold content > 99.999%: the width is 4.5 CM-5.5 CM, the thickness is 0.8 MM-1.2 MM;
b. putting the gold sheet into an ultrasonic cleaning machine, and cleaning for 2-5 minutes;
c. placing the mixture into an electric furnace with the temperature of 350-400 ℃ and baking for more than 15 minutes;
d. putting the cooled gold sheet into a reaction kettle for preparing gold water, firstly adding 1250 ml-1350 ml of nitric acid and 1250 ml-1350 ml of pure water into the reaction kettle for preparing the gold water, then adding 3750 ml-3850 ml of hydrochloric acid into the reaction kettle, and finally adding 2450 ml-2550 ml of hydrochloric acid into the reaction kettle in three to five times until the gold sheet is completely dissolved in the aqua regia;
e. and (3) heating the reaction kettle by using water vapor to keep the temperature of the reaction kettle between 90 and 100 ℃ for 40 to 50 minutes, and finishing nitrate removal when brown gas is not generated in the gold water any more.
2) Preparing the leic acid gold mud:
a. transferring the gold water after the nitrate removal into a gold fulminate reaction kettle, keeping the temperature in the gold fulminate reaction kettle between 70 and 80 ℃, slowly adding 6500ml to 7500ml of ammonia water, continuously stirring the reaction kettle, and reacting for half an hour to form slurry-like gold fulminate mud;
b. the method comprises the steps of filtering and cleaning the gold paste with a Buchner funnel, putting the cleaned gold paste into a gold paste reaction kettle, adding 1L-1.1L of distilled water, stirring uniformly, filtering and cleaning the gold paste with the Buchner funnel, adopting a three-layer stacking mode of paving filter cloth, filter paper and filter cloth in the Buchner funnel for filtering, repeatedly filtering and cleaning the gold paste for 8-10 times until the filtered water is neutral, and preparing the gold paste.
3) Preparing a gold sodium sulfite solution:
a. heating a reaction kettle to 70-80 ℃, adding 7700-7800 g of sodium sulfite into the gold sodium sulfite reaction kettle, adding 15-15.5L of hot water, and stirring for dissolving;
b. putting the leic acid gold mud into a sodium sulfite reaction kettle, and continuously stirring for 2-3 hours;
c. adding 5L-5.5L of sulfuric acid with the concentration of 5% -8% in two times, and reacting for more than 12 hours at an interval of more than 5 minutes in the two times, keeping the pH value between 9 and 11, so as to obtain the gold sodium sulfite solution with the gold content of 10-38 g/L.
4) Surface treatment:
a. hanging the gold ornaments to be electroformed on a specific bracket, putting the hanging bracket with the gold ornaments in a high-pressure cleaning water vat for cleaning for 30-60 seconds, and removing surface stains of the product;
b. putting the hanging rack with the gold ornaments into an ultrasonic cleaning machine containing paraffin removal water for cleaning for 30-60 seconds, and further removing oil stains, oxides and impurities on the surfaces of the ornaments;
c. cleaning in a high pressure cleaning water tank for 30-60 s to clean the surface;
d. putting the hanging rack with the gold ornaments into an electrolytic degreasing cylinder, adjusting the voltage to 3-5 v and the current to 20-40A, and the temperature in the cylinder to be 55-70 ℃ for 20-40 seconds to remove an oxide layer on the hanging rack and impurities on products;
e. and (3) putting the hanging rack with the gold ornaments into a washing water vat for washing for more than 3-4 times, then putting the hanging rack into a dilute sulphuric acid vat for pickling, and finally putting the hanging rack into the washing water vat for washing for 2 times.
5) Placing the gold ornamental article to be electroformed in an electroplating cylinder filled with a gold sodium sulfite solution, wherein the voltage in the electroplating cylinder is 3-5 v, the current in the electroplating cylinder is 20-40A, the electroplating cylinder is positively and reversely rotated once every 10 seconds, the rotating speed is 11-14 m/min, the temperature is 55-75 ℃, and the electroplating time is 0.5-3 h. And cleaning the surface of the electroplated product by using a manual watering can, then taking down the product, washing the surface of the electroplated product by using water vapor, and treating the washed product in the process after electroforming to obtain the gold ornament with the surface gold content of more than 99.995%.
Example 1
The bracelet is hung on a specific bracket, and after the electroplating process, the purity of the surface of the ornament is 99.9951 percent, the surface smoothness of the ornament is 0.05 and the Mohs hardness of the surface of the ornament is 4.0.
Example 2
The ring is hung on a specific bracket, and after the electroplating process, the purity of the surface of the ornament is 99.9951 percent, the surface smoothness of the ornament is 0.05 and the Mohs hardness of the surface of the ornament is 4.0.
Example 3
The earrings are hung on a specific bracket, and after the electroplating process, the purity of the surface of the ornament is 99.9951 percent, the surface smoothness of the ornament is 0.05 and the Mohs hardness of the surface of the ornament is 4.0.
Claims (6)
1. A cyanide-free electroplating process is characterized by comprising the following steps:
1) dissolving gold tablet with gold content of 99.999% in aqua regia, and removing nitre to obtain gold solution;
2) transferring the gold water to a gold fulminate reaction kettle, and slowly adding ammonia water to prepare gold fulminate mud;
3) putting the gold fulminate mud into a reaction kettle containing sodium sulfite, adding the gold fulminate mud under the stirring state, then adding sulfuric acid with the concentration of 5% -8%, and obtaining a gold sodium sulfite solution with the gold content of 10-38 g/L after reaction;
4) hanging the gold ornaments to be electroformed on a specific bracket, and removing dirt and impurities on the surface;
5) placing the gold ornament to be electroformed in an electroplating tank filled with a gold sodium sulfite solution, wherein the temperature is between 55 and 75 ℃, and the electroplating time is 0.5 to 3 hours, thus obtaining the gold ornament with the surface gold content of more than 99.995 percent.
2. The cyanide-free electroplating process according to claim 1, wherein the step 1) comprises the following steps:
a. tabletting gold tablets: the width is 4.5 CM-5.5 CM, the thickness is 0.8 MM-1.2 MM;
b. putting the gold sheet into an ultrasonic cleaning machine, and cleaning for 2-5 minutes;
c. placing the mixture into an electric furnace with the temperature of 350-400 ℃ and baking for more than 15 minutes;
d. putting the cooled gold sheet into a reaction kettle for preparing gold water, firstly adding 1250 ml-1350 ml of nitric acid and 1250 ml-1350 ml of pure water into the reaction kettle for preparing the gold water, then adding 3750 ml-3850 ml of hydrochloric acid into the reaction kettle, and finally adding 2450 ml-2550 ml of hydrochloric acid into the reaction kettle in three to five times until the gold sheet is completely dissolved in the aqua regia;
e. and (3) heating the reaction kettle by using water vapor to keep the temperature of the reaction kettle between 90 and 100 ℃ for 40 to 50 minutes, and finishing nitrate removal when brown gas is not generated in the gold water any more.
3. The cyanide-free electroplating process according to claim 1, wherein the step 2) comprises the following steps:
a. keeping the temperature in the reaction kettle of the gold fulminate at 70-80 ℃, slowly adding 6500 ml-7500 ml of ammonia water, continuously stirring the reaction kettle, and reacting for half an hour to form slurry-shaped gold fulminate mud;
b. and (2) filtering and cleaning the leic acid gold mud by using a Buchner funnel, putting the cleaned leic acid gold mud into a leic acid gold reaction kettle, adding 1L-1.1L of distilled water, uniformly stirring, filtering and cleaning the leic acid gold mud by using the Buchner funnel, and repeatedly filtering and cleaning the leic acid gold mud for 8-10 times until the filtered water is neutral.
4. The cyanide-free electroplating process according to claim 1, wherein the step 3) comprises the following steps:
a. heating a reaction kettle to 70-80 ℃, adding 7700-7800 g of sodium sulfite into the gold sodium sulfite reaction kettle, adding 15-15.5L of hot water, and stirring for dissolving;
b. putting the leic acid gold mud into a sodium sulfite reaction kettle, and continuously stirring for 2-3 hours;
c. adding 5L-5.5L of sulfuric acid with the concentration of 5% -8% in two times, and reacting for more than 12 hours, wherein the interval between the two times is more than 5 minutes, and the pH value is kept between 9 and 11.
5. The cyanide-free electroplating process according to claim 1, wherein the step 4) comprises the following steps:
a. putting the hanging rack with the gold ornaments into a high-pressure cleaning water vat for cleaning for 30-60 seconds;
b. cleaning in an ultrasonic cleaning machine containing wax removing water for 30-60 seconds;
c. putting the mixture into a high-pressure cleaning water tank again for cleaning for 30-60 seconds;
d. putting the hanger with gold ornaments into an electrolytic degreasing cylinder, adjusting the voltage to 3-5 v and the current to 20-40A, and controlling the temperature in the cylinder to be 55-70 ℃ for 20-40 seconds;
e. and (3) putting the hanging rack with the gold ornaments into a washing water vat for washing for more than 3-4 times, then putting the hanging rack into a dilute sulphuric acid vat for pickling, and finally putting the hanging rack into the washing water vat for washing for 2 times.
6. The cyanide-free electroplating process according to claim 1, wherein in the step 5), the voltage in the electroplating cylinder is 3v-5v, the current is 20A-40A, and the electroplating cylinder is adjusted in forward rotation and reverse rotation every 10 seconds at a rotating speed of 11 m/min-14 m/min.
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| CN201910674514.8A CN112301388A (en) | 2019-07-25 | 2019-07-25 | Cyanide-free electroplating process |
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| CN201910674514.8A CN112301388A (en) | 2019-07-25 | 2019-07-25 | Cyanide-free electroplating process |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114164465A (en) * | 2021-11-15 | 2022-03-11 | 深圳市联合蓝海黄金材料科技股份有限公司 | Sodium gold sulfite gold water and synthesis method and application thereof |
Citations (3)
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| CN105568269A (en) * | 2015-12-16 | 2016-05-11 | 励福(江门)环保科技股份有限公司 | Preparation method of cyanide-free gold plating reagent sodium gold sulfite |
| CN106637314A (en) * | 2016-12-15 | 2017-05-10 | 广东光华科技股份有限公司 | Preparation method of sodium gold sulfide solution for cyanide-free gold plating |
| CN108728873A (en) * | 2018-06-20 | 2018-11-02 | 深圳市金宝盈文化股份有限公司 | A kind of production method of casting gold process product |
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2019
- 2019-07-25 CN CN201910674514.8A patent/CN112301388A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105568269A (en) * | 2015-12-16 | 2016-05-11 | 励福(江门)环保科技股份有限公司 | Preparation method of cyanide-free gold plating reagent sodium gold sulfite |
| CN106637314A (en) * | 2016-12-15 | 2017-05-10 | 广东光华科技股份有限公司 | Preparation method of sodium gold sulfide solution for cyanide-free gold plating |
| CN108728873A (en) * | 2018-06-20 | 2018-11-02 | 深圳市金宝盈文化股份有限公司 | A kind of production method of casting gold process product |
Non-Patent Citations (1)
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114164465A (en) * | 2021-11-15 | 2022-03-11 | 深圳市联合蓝海黄金材料科技股份有限公司 | Sodium gold sulfite gold water and synthesis method and application thereof |
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Application publication date: 20210202 |