1. A recovery process of precious metals of waste circuit boards is characterized in that: the method comprises the following steps:

(1) stripping:

crushing the waste circuit board in an inert gas atmosphere to obtain mixed powder, and performing electrostatic separation to obtain metal mixed powder;

(2) separation:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A;

taking metal powder A, introducing hydrogen, charging hydrogen for reaction, and performing electrostatic separation to obtain metal palladium powder and metal powder B;

taking the metal powder B, introducing ozone, fully oxidizing, and carrying out electrostatic separation to obtain metal gold powder and metal powder C;

heating the metal powder C, and performing electrostatic separation to obtain silver powder;

(3) and (3) purification: and purifying the palladium powder, the gold powder and the silver powder.

2. The recovery process of noble metals of waste circuit boards according to claim 1, characterized in that: the step (1) comprises the following steps:

taking a waste circuit board, crushing the waste circuit board in an inert gas atmosphere to prepare mixed powder, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 25-30 kV, and the rotating speed of the roller is 72-76 rpm, so that the metal mixed powder is obtained.

3. The recovery process of noble metals of waste circuit boards according to claim 1, characterized in that: the step (2) comprises the following steps:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A;

taking metal powder A, introducing hydrogen, adjusting system conditions to 30-95 ℃, 800 Pa-24 kPa, 60-200 sccm of hydrogen flow and 10-20 h of hydrogen filling, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.5-3.0 kV, the rotating speed of a roller is 40-45 rpm, and the operation is repeated for 1-3 times to obtain metal palladium powder and metal powder B;

taking metal powder B, introducing ozone, adjusting system conditions to 15-40 ℃, reacting for 1-3 h at a relative humidity of 65-90%, and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.2-2.8 kV, the rotating speed of a roller is 48-53 rpm, and the steps are repeated for 1-2 times to obtain metal gold powder and metal powder C;

heating the metal powder C to constant weight at 250-300 ℃, cooling at room temperature, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.2-2.8 kV, the rotating speed of the roller is 53-58 rpm, and the process is repeated for 1-2 times to obtain the metal silver powder.

4. The recovery process of noble metals of waste circuit boards according to claim 1, characterized in that: the purification process of the palladium powder in the step (3) comprises the following steps: taking palladium powder, mechanically grinding, carrying out electrostatic separation, adding hydrochloric acid, fully reacting, filtering, taking precipitate, adding diethanolamine and ethanol, fully mixing, filtering, drying at 40-60 ℃ to constant weight, and repeating the operation to obtain the metal palladium.

5. The recovery process of noble metals of waste circuit boards according to claim 1, characterized in that: the purification process of the gold powder in the step (3) comprises the following steps: and (3) adding nitric acid into the gold powder, fully reacting, filtering, and cleaning and drying the precipitate to obtain the metal gold.

6. The recovery process of noble metals of waste circuit boards according to claim 1, characterized in that: the purification process of the silver powder in the step (3) comprises the following steps: taking silver powder, adding dilute sulfuric acid, introducing oxygen, fully reacting, filtering, taking precipitate, heating and drying to obtain the metallic silver.

7. The recovery process of noble metals of waste circuit boards according to claim 1, characterized in that: the average particle size of the mixed powder is 15-50 um.

Background

The circuit board is loaded with circuit on its surface, and can be miniaturized and visualized, and is formed from base, base copper, electroplated layer and surface protecting paint, etc. The common circuit board takes synthetic resin or glass fiber as a substrate, and a plurality of metals are loaded on the surface of the common circuit board, wherein the most metals are copper, and in addition, gold, aluminum, nickel, lead, silicon metals and the like are also contained, so that rare metals are not lacked. Compared with the common precious metal ore, the precious metal content in each ton of waste circuit boards is higher, so that the circuit boards can be regarded as the precious metal ore with quite high grade, the generation of waste minerals, air pollution and water pollution can be reduced, the energy consumption is reduced, and the waste circuit boards have very high recovery value and economic value and are beneficial to environmental protection. In the existing recovery process of precious metals of waste circuit boards, a large amount of chemical reagents are used for integrally dissolving the circuit boards and then carrying out chemical treatment such as extraction, so that the consumption of the reagents is high, a large amount of waste water is generated, and the influence on the environment is large. Therefore, a process for recovering noble metals from waste circuit boards is provided.

Disclosure of Invention

The invention aims to provide a process for recovering precious metals of waste circuit boards, which aims to solve the problems in the background technology.

In order to solve the technical problems, the invention provides the following technical scheme: a recovery process of precious metals of waste circuit boards comprises the following steps:

(1) stripping:

crushing the waste circuit board in an inert gas atmosphere to obtain mixed powder, performing electrostatic separation, and removing semiconductors in the mixed powder to obtain metal mixed powder;

(2) separation:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A;

taking metal powder A, introducing hydrogen, charging hydrogen for reaction, and performing electrostatic separation to obtain metal palladium powder and metal powder B;

taking the metal powder B, introducing ozone, fully oxidizing, and carrying out electrostatic separation to obtain metal gold powder and metal powder C;

heating the metal powder C, and performing electrostatic separation to obtain silver powder;

(3) and (3) purification: purifying palladium powder, gold powder and silver powder

Further, the step (1) comprises the steps of:

taking a waste circuit board, crushing the waste circuit board in an inert gas atmosphere to prepare mixed powder, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 25-30 kV, and the rotating speed of the roller is 72-76 rpm, so that the metal mixed powder is obtained.

In the technical scheme, the components of the waste circuit board comprise non-conductor synthetic resin and non-alloy conductor metal copper, gold, silver and palladium; the waste circuit board is mechanically crushed, because the brittleness and the toughness of the metal and the synthetic resin are different, when the circuit board is crushed to a certain particle size, the metal and the synthetic resin can be completely peeled off, and each component metal exists in a certain thickness, and each component metal can be primarily separated after crushing; then carrying out electrostatic separation on the crushed mixed powder, separating a non-conductor from a conductor, and removing the synthetic resin in the non-conductor to obtain metal mixed powder;

further, the step (2) comprises the following steps:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A; separating iron from other metals by utilizing magnetism, wherein the obtained metal powder A contains metal copper, gold, silver and palladium;

taking metal powder A, introducing hydrogen, adjusting system conditions to 30-95 ℃, 800 Pa-24 kPa, 60-200 sccm of hydrogen flow and 10-20 h of hydrogen filling, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.5-3.0 kV, the rotating speed of a roller is 40-45 rpm, and the operation is repeated for 1-3 times to obtain metal palladium powder and metal powder B; the metal palladium absorbs hydrogen to form a palladium hydrogen compound, which is a semiconductor when the hydrogen charging rate is more than 0.5, and the semiconductor and the conductor can be separated by electrostatic separation; the hydrogen expands the volume of the metal palladium, weakens the bonding strength with other metals/substances, further separates the metals of each component and promotes the sufficient separation of the metal palladium; the metal powder A contains metal gold, so that the absorption of metal palladium on hydrogen can be promoted, the aeration rate of palladium is improved, the hydrogen flow is low, and the influence on the plasticity of metal palladium is avoided; the metal powder B contains metal copper, gold and silver;

taking metal powder B, introducing ozone, adjusting system conditions to 15-40 ℃, reacting for 1-3 h at a relative humidity of 65-90%, and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.2-2.8 kV, the rotating speed of a roller is 48-53 rpm, and the steps are repeated for 1-2 times to obtain metal gold powder and metal powder C; the silver and copper react with ozone to generate oxidized silver and copper, the conductivity is greatly reduced, and the silver and copper are separated from unreacted metal gold by electrostatic separation; the form of copper is changed, the bonding strength between the copper and other metals/substances is weakened, the metals of all components are further separated, and the full separation of metal gold is promoted; the metal powder C contains metal copper and silver;

heating the metal powder C to constant weight at 250-300 ℃, cooling at room temperature, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.2-2.8 kV, the rotating speed of a roller is 53-58 rpm, and the steps are repeated for 1-2 times to obtain the metal silver powder; the oxidation state silver is subjected to reduction reaction in the temperature range to generate metal silver, the conductivity is recovered, electrostatic separation is carried out, the metal silver can be separated from unreduced oxidation state copper to obtain metal silver powder and copper powder, the copper powder can be purified and recovered in a conventional mode, and oxygen generated by reduction of the oxidation state silver can be recovered and used in the step (3), so that the method is more environment-friendly;

further, the purification process of the palladium powder in the step (3) comprises the following steps: taking palladium powder, mechanically grinding, carrying out electrostatic separation, adding hydrochloric acid, fully reacting, filtering, taking precipitate, adding diethanolamine and ethanol, fully mixing, filtering, drying at 40-60 ℃ to constant weight, and repeating the operation to obtain the metal palladium. The obtained palladium powder is a palladium hydrogen compound, wherein adhered metal silver, gold and copper may exist, oxidized copper and silver may exist, and purification treatment is needed; mechanically grinding palladium powder, stripping the palladium powder from other metals/substances, carrying out electrostatic separation, removing conductive metals such as gold and silver, dissolving copper, copper oxide and silver oxide by using hydrochloric acid to generate copper chloride and silver chloride precipitates dissolved in water, filtering, adding diethanol amine and ethanol into the precipitates, complexing and dissolving silver chloride and free silver ions, filtering, repeating the steps for multiple times, taking the precipitates, cleaning to obtain a metal palladium hydride, heating and drying, and removing hydrogen to obtain purified metal palladium; the released hydrogen can be recycled, so that the energy is saved and the environment is protected; adding hydrochloric acid into the separated conductor metal gold and silver for reaction, filtering, taking precipitate, adding ethanol solution of diethanol amine for mixing, repeatedly separating and reducing the metal gold and silver, and adding the metal gold and silver into the purified metal gold and silver; reducing silver in the filtrate, and adding the silver into the purified silver;

further, the gold powder purification process in the step (3) comprises the following steps: and (3) adding nitric acid into the gold powder, fully reacting, filtering, and cleaning and drying the precipitate to obtain the metal gold. The obtained gold powder may contain unoxidized metal silver, copper and hydrogen-charged palladium; dissolving silver, palladium and copper in nitric acid, filtering, and cleaning and drying the precipitate to obtain purified gold; adding hydrochloric acid into the filtrate, filtering to remove precipitated silver chloride, adding nitric acid into the filtrate to chlorinate palladium into tetravalent palladium, adding ammonium chloride, boiling to dissolve, cooling, filtering, and repeating for multiple times to obtain ammonium chloropalladate; reducing silver chloride and ammonium chloropalladate in sequence, and adding the silver chloride and the ammonium chloropalladate into purified silver and palladium;

further, the process for purifying the silver powder in the step (3) comprises the following steps: taking silver powder, adding dilute sulfuric acid, introducing oxygen, fully reacting, filtering, taking precipitate, heating and drying to obtain the metallic silver. The silver powder may contain metallic copper and silver oxide, and is reacted with dilute sulfuric acid and oxygen to obtain copper sulfate, filtered, deposited, heated to reduce the silver sulfate and dried to obtain purified metallic silver.

Further, the average particle size of the mixed powder is 10-50 um.

The obtained palladium powder, gold powder and silver powder, wherein the metal powder A, B, C may contain unseparated synthetic resin, and the bonding with other metals/substances is reduced due to the structural change of the metal, so that the substances can be respectively mechanically ground and electrostatically separated in the separation process to separate a nonconductor from a conductor and a semiconductor; the nonconductor obtained in the step (1) can also be placed in a separation process to separate metals and oxides thereof possibly remaining in the nonconductor, so that the recovery rate of the noble metals is improved.

Compared with the prior art, the invention has the following beneficial effects:

according to the recovery process of the precious metals of the waste circuit boards, the metals and the synthetic resin are completely stripped through mechanical crushing, the synthetic resin, the metal palladium, the metal gold, the metal silver and the metal copper in the circuit boards are sequentially separated by utilizing an electrostatic separation technology to obtain the coarsened metals of all components, and then the coarsened metals are respectively chemically purified.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it should be understood 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.

Example 1

(1) Stripping:

taking a waste circuit board, crushing the waste circuit board in an inert gas atmosphere to prepare mixed powder, wherein the average particle size of the mixed powder is 50um, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 25kV, the rotating speed of the roller is 76rpm, and metal mixed powder is obtained;

(2) separation:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A;

taking metal powder A, introducing hydrogen, adjusting the system conditions to 95 ℃, 800Pa, 60sccm of hydrogen flow, charging hydrogen for 10h, and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.5kV, the rotating speed of the roller is 40rpm, and the operation is repeated for 2 times to obtain metal palladium powder and metal powder B;

taking the metal powder B, introducing ozone, adjusting the system conditions to 15 ℃ and 65% of relative humidity, reacting for 1h, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.2kV, the rotating speed of the roller is 48rpm, and the steps are repeated for 1 time to obtain metal gold powder and metal powder C;

heating the metal powder C at 250 ℃ to constant weight, cooling at room temperature, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.2kV, the rotating speed of the roller is 53rpm, and the metal silver powder is obtained;

(3) and (3) purification:

taking palladium powder, mechanically grinding and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.5kV, the rotating speed of a roller is 40rpm, hydrochloric acid is added, the mixture is fully reacted and filtered, precipitate is taken and added into an ethanol solution of diethanolamine, the mixture is fully mixed and filtered, and the mixture is dried to constant weight at 40 ℃ to obtain metal palladium;

adding nitric acid into gold powder, fully reacting, filtering, and cleaning and drying the precipitate to obtain metal gold;

taking silver powder, adding dilute sulfuric acid, introducing oxygen, fully reacting, filtering, taking precipitate, heating and drying to obtain the metallic silver.

Example 2

(1) Stripping:

taking a waste circuit board, crushing the waste circuit board in an inert gas atmosphere to prepare mixed powder, wherein the average particle size of the mixed powder is 30um, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 27kV, the rotating speed of the roller is 74rpm, and metal mixed powder is obtained;

(2) separation:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A;

taking the metal powder A, introducing hydrogen, adjusting the system conditions to 65 ℃, 12kPa, 130sccm of hydrogen flow, charging hydrogen for 15h, and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.7kV, the rotating speed of a roller is 42rpm, and the operation is repeated for 2 times to obtain metal palladium powder and metal powder B;

taking the metal powder B, introducing ozone, adjusting the system conditions to 27 ℃, and reacting for 2h at a relative humidity of 78%, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.6kV, the rotating speed of the roller is 50rpm, and the operation is repeated for 2 times to obtain metal gold powder and metal powder C;

heating the metal powder C at 270 ℃ to constant weight, cooling at room temperature, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.6kV, the rotating speed of the roller is 55rpm, and the process is repeated for 2 times to obtain the metal silver powder;

(3) and (3) purification:

taking palladium powder, mechanically grinding and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.7kV, the rotating speed of a roller is 42rpm, hydrochloric acid is added, the mixture is fully reacted and filtered, precipitate is taken and added into ethanol solution of diethanolamine, the mixture is fully mixed and filtered, and the mixture is dried to constant weight at 50 ℃ to obtain metal palladium;

adding nitric acid into gold powder, fully reacting, filtering, and cleaning and drying the precipitate to obtain metal gold;

taking silver powder, adding dilute sulfuric acid, introducing oxygen, fully reacting, filtering, taking precipitate, heating and drying to obtain the metallic silver.

Example 3

(1) Stripping:

taking a waste circuit board, crushing the waste circuit board in an inert gas atmosphere to prepare mixed powder, wherein the average particle size of the mixed powder is 15um, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 30kV, the rotating speed of the roller is 72rpm, and metal mixed powder is obtained;

(2) separation:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A;

taking metal powder A, introducing hydrogen, adjusting system conditions to 95 ℃, 24kPa, 200sccm hydrogen flow, charging hydrogen for 20h, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 3.0kV, the rotating speed of the roller is 40rpm, and the operation is repeated for 3 times to obtain metal palladium powder and metal powder B;

taking the metal powder B, introducing ozone, adjusting the system conditions to 40 ℃, relative humidity 90%, reacting for 3h, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.8kV, the rotating speed of the roller is 48rpm, and the process is repeated for 2 times to obtain metal gold powder and metal powder C;

heating the metal powder C at 300 ℃ to constant weight, cooling at room temperature, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.8kV, the rotating speed of the roller is 53rpm, and the process is repeated for 2 times to obtain the metal silver powder;

(3) and (3) purification:

taking palladium powder, mechanically grinding and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 3.0kV, the rotating speed of a roller is 40rpm, hydrochloric acid is added, the mixture is fully reacted and filtered, precipitate is taken and added into ethanol solution of diethanolamine, the mixture is fully mixed and filtered, and the mixture is dried to constant weight at 60 ℃ to obtain metal palladium;

adding nitric acid into gold powder, fully reacting, filtering, and cleaning and drying the precipitate to obtain metal gold;

taking silver powder, adding dilute sulfuric acid, introducing oxygen, fully reacting, filtering, taking precipitate, heating and drying to obtain the metallic silver.

Comparative example 1

(1) Stripping:

taking a waste circuit board, crushing the waste circuit board in an inert gas atmosphere to prepare mixed powder, wherein the average particle size of the mixed powder is 120um, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 27kV, the rotating speed of the roller is 74rpm, and metal mixed powder is obtained;

(2) separation:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A;

taking the metal powder A, introducing hydrogen, adjusting the system conditions to 65 ℃, 12kPa, 130sccm of hydrogen flow, charging hydrogen for 15h, and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.7kV, the rotating speed of a roller is 42rpm, and the operation is repeated for 2 times to obtain metal palladium powder and metal powder B;

taking the metal powder B, introducing ozone, adjusting the system conditions to 27 ℃, and reacting for 2h at a relative humidity of 78%, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.6kV, the rotating speed of the roller is 50rpm, and the operation is repeated for 2 times to obtain metal gold powder and metal powder C;

heating the metal powder C at 270 ℃ to constant weight, cooling at room temperature, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.6kV, the rotating speed of the roller is 55rpm, and the process is repeated for 2 times to obtain the metal silver powder;

(3) and (3) purification:

(3) and (3) purification:

taking palladium powder, mechanically grinding and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.7kV, the rotating speed of a roller is 42rpm, hydrochloric acid is added, the mixture is fully reacted and filtered, precipitate is taken and added into ethanol solution of diethanolamine, the mixture is fully mixed and filtered, and the mixture is dried to constant weight at 50 ℃ to obtain metal palladium;

adding nitric acid into gold powder, fully reacting, filtering, and cleaning and drying the precipitate to obtain metal gold;

taking silver powder, adding dilute sulfuric acid, introducing oxygen, fully reacting, filtering, taking precipitate, heating and drying to obtain the metallic silver.

Comparative example 2

(1) Stripping:

taking a waste circuit board, crushing the waste circuit board in an inert gas atmosphere to prepare mixed powder, wherein the average particle size of the mixed powder is 30um, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 27kV, the rotating speed of the roller is 74rpm, and metal mixed powder is obtained;

(2) separation:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A;

taking the metal powder A, introducing hydrogen, adjusting the system conditions to 65 ℃, 12kPa, 130sccm of hydrogen flow, charging hydrogen for 15h, and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.7kV, the rotating speed of a roller is 42rpm, and the operation is repeated for 2 times to obtain metal palladium powder and metal powder B;

taking the metal powder B, introducing ozone, adjusting the system conditions to 27 ℃, and reacting for 2h at a relative humidity of 78%, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.6kV, the rotating speed of the roller is 50rpm, and the operation is repeated for 2 times to obtain metal gold powder and metal powder C;

heating the metal powder C at 370 ℃ to constant weight, cooling at room temperature, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.6kV, the rotating speed of the roller is 55rpm, and the process is repeated for 2 times to obtain the metal silver powder;

(3) and (3) purification:

taking palladium powder, mechanically grinding and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.7kV, the rotating speed of a roller is 42rpm, hydrochloric acid is added, the mixture is fully reacted and filtered, precipitate is taken and added into ethanol solution of diethanolamine, the mixture is fully mixed and filtered, and the mixture is dried to constant weight at 50 ℃ to obtain metal palladium;

adding nitric acid into gold powder, fully reacting, filtering, and cleaning and drying the precipitate to obtain metal gold;

taking silver powder, adding dilute sulfuric acid, introducing oxygen, fully reacting, filtering, taking precipitate, heating and drying to obtain the metallic silver.

Comparative example 3

(1) Stripping:

taking a waste circuit board, crushing the waste circuit board in an inert gas atmosphere to prepare mixed powder, wherein the average particle size of the mixed powder is 30um, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 27kV, the rotating speed of the roller is 74rpm, and metal mixed powder is obtained;

(2) separation:

carrying out magnetic separation on metal powder to obtain iron powder and metal powder A;

taking the metal powder A, introducing hydrogen, adjusting the system conditions to 65 ℃, 12kPa, 130sccm of hydrogen flow, charging hydrogen for 15h, and carrying out electrostatic separation, wherein the process comprises the following steps: the voltage is 2.7kV, the rotating speed of the roller is 42rpm, and the operation is repeated for 2 times to obtain metal palladium and metal powder B;

taking the metal powder B, introducing ozone, adjusting the system conditions to 27 ℃, and reacting for 2h at a relative humidity of 78%, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.6kV, the rotating speed of the roller is 50rpm, and the process is repeated for 2 times to obtain metal gold and metal powder C;

heating the metal powder C at 270 ℃ to constant weight, cooling at room temperature, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 2.6kV, the rotating speed of the roller is 55rpm, and the process is repeated for 2 times to obtain the metallic silver.

Comparative example 4

Taking a waste circuit board, crushing the waste circuit board in an inert gas atmosphere to prepare mixed powder, wherein the average particle size of the mixed powder is 30um, and performing electrostatic separation, wherein the process comprises the following steps: the voltage is 27kV, the rotating speed of the roller is 74rpm, and metal mixed powder is obtained;

adding concentrated nitric acid into the metal mixed powder, fully reacting, filtering, drying the precipitate to obtain gold, adding concentrated hydrochloric acid, wherein the volume ratio of the concentrated nitric acid to the concentrated hydrochloric acid is 1:3, filtering, drying the precipitate to obtain silver chloride, adding ammonia water and hydrochloric acid into the filtrate, and drying the precipitate to obtain dichlorodiamminepalladium; and reducing and purifying the obtained gold, silver chloride and dichlorodiammine palladium to obtain metal gold, metal silver and metal palladium.

Experiment of

The noble metals obtained in examples 1 to 3 and comparative examples 1 to 4 were used to prepare samples, and the recovery and purity were measured and the results were recorded:

from the data in the table above, it is clear that the following conclusions can be drawn:

the noble metals obtained in examples 1 to 3 and the noble metals obtained in comparative examples 1 to 4 are compared, wherein the average particle size of the mixed powder in comparative example 1 is different, the temperature setting in comparative example 2 is different, the noble metal obtained in comparative example 3 is not purified, and the noble metal obtained in comparative example 4 is separated by a chemical method, and the test results show that:

compared with the noble metal obtained in the comparative example 4, the recovery rate and the purity data of the noble metal obtained in the examples 1 to 3 are obviously better, and the method can realize the recovery of the noble metal in the waste circuit board; and compared with the noble metal obtained in example 2, the data in comparative examples 1 to 3 are significantly reduced, and it is understood that the provision of the pulverized particle size and the purification process can improve the recovery rate and purity of the obtained noble metal, and is advantageous for the recovery thereof.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Furthermore, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process method article or apparatus.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.