CN111501073A - Method for prolonging service life of cyanide-free gold sodium sulfite-ethylenediamine electroplating solution - Google Patents
Method for prolonging service life of cyanide-free gold sodium sulfite-ethylenediamine electroplating solution Download PDFInfo
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- CN111501073A CN111501073A CN202010334145.0A CN202010334145A CN111501073A CN 111501073 A CN111501073 A CN 111501073A CN 202010334145 A CN202010334145 A CN 202010334145A CN 111501073 A CN111501073 A CN 111501073A
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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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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D21/00—Processes for servicing or operating cells for electrolytic coating
- C25D21/02—Heating or cooling
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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
- C25D21/00—Processes for servicing or operating cells for electrolytic coating
- C25D21/16—Regeneration of process solutions
- C25D21/18—Regeneration of process solutions of electrolytes
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Abstract
The invention discloses a method for prolonging the service life of cyanide-free gold sodium sulfite-ethylenediamine electroplating solution, which comprises the following operation steps: s1: evaporating the electroplating solution with the Baume value of 30-35 degrees Be' at 40-60 ℃ until crystal grains appear at the bottom of the solution, and stopping heating; s2: then, starting a cooling mode, controlling the cooling rate at 10-15 ℃/h, and controlling the cooling crystallization temperature at 0-10 ℃; s3: when the baume value of the electroplating mother liquor is reduced to Be within the range of 20-25 degrees Be', the crystallization is considered to Be finished; the newly obtained electroplating solution does not influence the product quality, the depth capability is further improved, and the electroplating solution can be repeatedly used by removing excessive salts through a crystallization method, so that the cost of cyanide-free electroplating gold is greatly reduced, and the main confusion of the cyanide-free electroplating gold at present is solved.
Description
Technical Field
The invention relates to the technical field of prolonging the service life of cyanide-free sodium gold sulfite-ethylenediamine electroplating solution, in particular to a method for prolonging the service life of cyanide-free sodium gold sulfite-ethylenediamine electroplating solution.
Background
At present, gold electroplating by using cyanide-free sulfurous acid is mainly applied to the types of sulfite, namely, citrate, sulfite, namely, tartrate, sulfite, namely, phosphate, sulfite, namely, organic phosphonate, sulfite, namely, ethylenediamine and the like. In order to keep the plating solution stable, most types of plating solutions require, on the one hand, a large amount of additives, in particular organic co-complexing agents; on the other hand, because of the consumption of gold ions, the gold sulfite salt is required to be continuously supplemented, and the gold sulfite salt continuously releases sulfite in the electroplating process, and the sulfite is easy to oxidize, and a part of the sulfite is converted into sulfate; in addition, in order to maintain the sulfite concentration within a reasonable range, it is sometimes necessary to supplement a certain amount of sulfite. In short, as the electroplating is continuously carried out, the baume value of the electroplating solution is continuously increased by various factors.
In the 3D hard gold industry, a cyanide-free sulfite electroplating gold system is adopted, and each cylinder of electroplating products is measured by kilograms. When the cylinder is opened, the baume value of the electroplating solution is about 15 degrees Be ', and the baume value is increased by about 1 degree Be' every time 1Kg of gold products are electroplated. After 15-20 Kg of gold product is electroplated, the baume value of the electroplating solution reaches 30-35 DEG Be', and the product quality is difficult to meet the requirement when electroplating is carried out within the range of the baume value. If the total weight of the gold product is compared with the output of cyanide plating, the difference is obvious. Therefore, the cost of the cyanide-free sulfite electroplating gold is high, and the popularization and the application are limited.
There are no methods available to extend the service life of the plating solution? From the prior common type of sulfite-auxiliary complexing agent, the organic additive has larger application amount and more varieties. Because a large amount of organic matters are introduced into the electroplating solution, the crystallization method is tried to eliminate excessive salts, and the success is not easy. It is known that sodium sulfate and sodium sulfite are easy to crystallize by combining evaporation and cooling, but when a large amount of organic salts exist, the crystallization behaviors of sodium sulfate and sodium sulfite are seriously influenced. Therefore, there is a need to develop a gold sodium sulfite electroplating gold system that avoids the introduction of a large amount of organic salt auxiliary complexing agent, and the added auxiliary complexing agent must reduce interference with the crystallization behavior of sodium sulfate and sodium sulfite. Under the guidance of the idea, a gold system for plating gold by using sodium bisulfite and ethylenediamine is found to be ideal, and in the system, the dosage of an organic auxiliary complexing agent is small, and the interference on the crystallization behavior of sodium sulfate and sodium sulfite is weak. The system is particularly suitable for crystallizing a certain amount of sodium sulfate and sodium sulfite by adopting a crystallization mode, removing a certain amount of redundant salts and reducing the baume value of the electroplating solution. During the crystallization process, less of the beneficial components of the electroplating solution are lost. And stopping crystallization after the baume value of the electroplating mother liquor is reduced to the range of 20-25 degrees Be', and adjusting additives to Be supplemented according to the result of the copper sheet by the obtained electroplating mother liquor through a Hull cell test. The newly obtained electroplating solution does not influence the product quality and has further improvement on the deep plating capacity.
The invention solves the method for removing the redundant sodium sulfate and sodium sulfite salts in the gold system of the gold sodium sulfite-ethylenediamine electroplating by a crystallization mode, and regenerates the electroplating solution. Because the crystallization method can be repeatedly adopted, the normal operation time of electroplating production is greatly prolonged, and the cost of cyanide-free gold electroplating is greatly reduced. At present, the method is applied to actual production of enterprises, has ideal effect and is worth popularizing and applying in the 3D hard gold industry.
As can be seen from Table 1 (data in Table 1 is from technical Crystal 272, Ed. forceful, Dingshuihuai, Inc.), the solubility of sodium sulfate and sodium sulfite is the greatest at 30-40 deg.C, and the difference is significant compared with the solubility data below 10 deg.C, especially the difference is 5-10 times. Therefore, in principle, a certain amount of salts can be removed by crystallization.
In the electroplating solution, part of sodium sulfite comes from the continuously supplemented gold sodium sulfite solution; the other part is added as conductive salt, and during crystallization, the sulfite needs to be kept in a reasonable content to ensure the stability of the electroplating solution. The data in table 1 show that the solubility data for sodium sulfite is very desirable below 10 ℃ to ensure that the sodium sulfite concentration is within the normal range. The sodium sulfate is derived from continuous oxidation of sodium sulfite in the electroplating process, the sodium sulfate only plays a conductive role, and the positive effect in the electroplating process is weak, but the sodium sulfate is one of main substances for increasing the Baume value of the electroplating solution. Therefore, it is important to remove as much as possible of the sodium sulfate crystals while crystallizing part of the sodium sulfite.
In actual production, the baume value of the electroplating solution is increased to Be within the range of 30-35 degrees Be', the quality of an electroplated product cannot meet the requirements, for example, the product has insufficient color, poor brightness and poor appearance due to particle formation on the surface.
Disclosure of Invention
The invention aims to provide a method for prolonging the service life of cyanide-free gold sodium sulfite-ethylenediamine electroplating solution, which is characterized in that the electroplating solution with the baume value of 30-35 DEG Be 'is crystallized by combining evaporation and cooling, and when the baume value of the electroplating solution is reduced to Be within the range of 20-25 DEG Be', the crystallization is completed, so as to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme: a method for prolonging the service life of cyanide-free gold sodium sulfite-ethylenediamine electroplating solution comprises the following operation steps:
s1: evaporating the electroplating solution with the Baume value of 30-35 degrees Be' at 40-60 ℃ until crystal grains appear at the bottom of the solution, and stopping heating;
s2: then, starting a cooling mode, controlling the cooling rate at 10-15 ℃/h, and controlling the cooling crystallization temperature at 0-10 ℃;
s3: when the baume value of the electroplating mother liquor is reduced to Be within the range of 20-25 degrees Be', the crystallization is considered to Be finished;
s4: in the crystallization process, the balance of supersaturated solution can be broken by adopting stirring, ultrasonic or adding seed crystals, so that the crystallization speed is accelerated;
and S5, performing solid-liquid separation, controlling the volume of the electroplating solution to be 220-240L, supplementing required additives according to the test result of the Hull cell, adjusting the solution of the electroplating cylinder to the specified liquid level, and completing the regeneration of the electroplating mother solution.
Preferably: the rotating speed of the stirring device proposed in the step S4 is 100 r/min.
Preferably: the frequency of the ultrasonic device is selected to be 20-40 Hz.
Preferably, in the seed crystal adding mode, the concentration of the sodium sulfate seed crystal is 0.01-0.02 g/L of the volume of the electroplating solution.
Compared with the prior art, the method has the advantages that the baume value of the electroplating solution can Be reduced to the range of 20-25 degrees Be' through a crystallization process, the concentration of sodium sulfate and sodium sulfite salt is effectively reduced, the concentration range of the sodium gold sulfite brought out along with components in the crystallization process is 1-5 g/L, and less auxiliary additives are brought out.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A method for prolonging the service life of cyanide-free gold sodium sulfite-ethylenediamine electroplating solution comprises the following operation steps:
s1: heating the electroplating solution with the Baume value of 30-35 degrees Be' at 40-60 ℃ to evaporate the electroplating solution until crystal grains appear at the bottom of the solution, indicating that the solution is already in a saturated solution, and stopping heating. Because sodium sulfate is easy to form supersaturated solution, sometimes it is difficult to separate out crystal, when the evaporation volume can be controlled to reduce about one third, the heating evaporation process is stopped. When the evaporation temperature is higher than 60 ℃, the solubility of sodium sulfate and sodium sulfite is reduced, and crystallization is separated out too early, which is not beneficial to subsequent operation; when the evaporation temperature is less than 40 ℃, the evaporation time is too long, which is not beneficial to work arrangement;
s2: starting a cooling mode, controlling the cooling rate at 10-15 ℃/h, controlling the crystallization cooling temperature at 0-10 ℃, completing crystallization when the baume value of the electroplating mother liquor is reduced to Be within the range of 20-25 DEG Be', having large cooling rate and relatively better crystallization effect, wasting energy and working time when the crystallization temperature is lower than 0 ℃, and having large loss of part of additives; when the crystallization temperature is higher than 10 ℃, the crystallization effect is not ideal, and the baume value of the electroplating solution is not in a reasonable requirement range;
s3, in the crystallization process, the balance of supersaturated solution can be broken by adopting a stirring, ultrasonic or crystal seed adding mode, the crystallization speed is accelerated, the stirring mode is adopted, the rotating speed is controlled to be 100r/min, the ultrasonic mode is adopted, the frequency is selected to be 20-40 Hz, the crystal seed adding mode is adopted, and the concentration of the sodium sulfate crystal seed is 0.01-0.02 g/L of the volume of the electroplating solution;
and S4, after the crystallization is finished, adjusting the volume of the electroplating solution, performing a Hull cell test, observing the effect of the copper sheet, adding additives to be supplemented, and under the normal condition of the crystallization, adding 4-8L of the reagent A, 2-4L of the reagent B, 1-2L of the reagent C, and finishing the regeneration of the electroplating mother solution.
Examples
Step one, testing the baume value of the electroplating solution, and when the baume value reaches 34 degrees Be' (the concentration of sodium sulfite is about 120 g/L, the concentration of sodium sulfate is about 60 g/L), cutting off the power supply, stopping stirring, and preparing for crystallization;
step two: pumping the electroplating solution into a cubic crystallization box by using a peristaltic pump;
step three: starting a control system, and setting the heating temperature to be 40 ℃; the stirring speed is 100 r/min;
step four: continuously heating and stirring for 12 hours, observing the bottom of the crystallization box, and stopping heating when the solution reaches a saturated state if crystal grains are separated out;
step five: returning to the control system, setting the cooling temperature on the control panel to be 5 ℃, cooling the electroplating solution, controlling the cooling rate to be about 15 ℃/h, and separating out a large amount of salt crystals when the temperature of the electroplating solution is close to 5 ℃;
step six: determining the baume value of the electroplating mother liquor to Be 22 DEG Be', completing the crystallization, and performing solid-liquid separation;
seventhly, adjusting the volume of the industrial electroplating cylinder to about 250L, adjusting the volume of the electroplating mother liquor to 240L, dividing the solution required by the experiment, performing a Hull cell experiment, and supplementing 6L of the reagent A, 3L of the reagent B and 1.5L of the reagent C under the normal crystallization condition.
Table 1: solubility of sodium sulfate and sodium sulfite in Water at different temperatures (g anhydrate/100 g water)
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (4)
1. A method for prolonging the service life of cyanide-free gold sodium sulfite-ethylenediamine electroplating solution is characterized in that: the method comprises the following operation steps:
s1: evaporating the electroplating solution with the Baume value of 30-35 degrees Be' at 40-60 ℃ until crystal grains appear at the bottom of the solution, and stopping heating;
s2: then, starting a cooling mode, controlling the cooling rate at 10-15 ℃/h, and controlling the cooling crystallization temperature at 0-10 ℃;
s3: when the baume value of the electroplating mother liquor is reduced to Be within the range of 20-25 degrees Be', the crystallization is considered to Be finished;
s4: in the crystallization process, the balance of supersaturated solution can be broken by adopting stirring, ultrasonic or adding seed crystals, so that the crystallization speed is accelerated;
and S5, performing solid-liquid separation, controlling the volume of the electroplating solution to be 220-240L, supplementing required additives according to the test result of the Hull cell, adjusting the solution of the electroplating cylinder to the specified liquid level, and completing the regeneration of the electroplating mother solution.
2. The method of claim 1, wherein the step of extending the lifetime of the cyanide-free gold sodium sulfite-ethylenediamine electroplating solution comprises: the rotating speed of the stirring device proposed in the step S4 is 100 r/min.
3. The method of claim 1, wherein the step of extending the lifetime of the cyanide-free gold sodium sulfite-ethylenediamine electroplating solution comprises: the frequency of the ultrasonic device is selected to be 20-40 Hz.
4. The method as claimed in claim 1, wherein the seeding is performed in such a way that the concentration of the sodium sulfate seed crystals is 0.01-0.02 g/L of the volume of the electroplating solution.
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Citations (8)
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|---|---|---|---|---|
| JPS56108892A (en) * | 1980-01-31 | 1981-08-28 | Electroplating Eng Of Japan Co | Plating solution with pure gold |
| CN1818133A (en) * | 2006-03-17 | 2006-08-16 | 华南理工大学 | Regenerating treatment of chemical nickel-plating liquid |
| JP2006322037A (en) * | 2005-05-18 | 2006-11-30 | Electroplating Eng Of Japan Co | Gold-plating solution |
| CN101413118A (en) * | 2008-11-06 | 2009-04-22 | 浙江工业大学 | Method for extending service-life of chemical nickel plating solution |
| JP2011184734A (en) * | 2010-03-08 | 2011-09-22 | Electroplating Eng Of Japan Co | Gold plating method using sulfite gold plating liquid |
| CN105112953A (en) * | 2015-09-17 | 2015-12-02 | 深圳市瑞世兴科技有限公司 | Cyanide-free gold plating solution |
| CN109881223A (en) * | 2019-03-11 | 2019-06-14 | 深圳市联合蓝海科技开发有限公司 | Cyanogen-less gold liquid and its preparation method and application |
| CN109913912A (en) * | 2019-04-02 | 2019-06-21 | 深圳市昊扬电铸技术开发有限公司 | A kind of electroforming solution for gold without cyanogen electroforming process |
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2020
- 2020-04-24 CN CN202010334145.0A patent/CN111501073A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56108892A (en) * | 1980-01-31 | 1981-08-28 | Electroplating Eng Of Japan Co | Plating solution with pure gold |
| JP2006322037A (en) * | 2005-05-18 | 2006-11-30 | Electroplating Eng Of Japan Co | Gold-plating solution |
| CN1818133A (en) * | 2006-03-17 | 2006-08-16 | 华南理工大学 | Regenerating treatment of chemical nickel-plating liquid |
| CN101413118A (en) * | 2008-11-06 | 2009-04-22 | 浙江工业大学 | Method for extending service-life of chemical nickel plating solution |
| JP2011184734A (en) * | 2010-03-08 | 2011-09-22 | Electroplating Eng Of Japan Co | Gold plating method using sulfite gold plating liquid |
| CN105112953A (en) * | 2015-09-17 | 2015-12-02 | 深圳市瑞世兴科技有限公司 | Cyanide-free gold plating solution |
| CN109881223A (en) * | 2019-03-11 | 2019-06-14 | 深圳市联合蓝海科技开发有限公司 | Cyanogen-less gold liquid and its preparation method and application |
| CN109913912A (en) * | 2019-04-02 | 2019-06-21 | 深圳市昊扬电铸技术开发有限公司 | A kind of electroforming solution for gold without cyanogen electroforming process |
Non-Patent Citations (1)
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