Method for recovering gold from circuit board

Abstract

The invention discloses a method for recovering gold from a circuit board, and relates to the technical field of precious metal refinement, and the method comprises the following steps: carrying out preliminary crushing on the circuit board, and heating the crushed circuit board to obtain a gold-containing polished board; a supercritical fluid extraction technology is used for extracting the gold-containing light plate, dissolved organic components are separated out, and a pure metal substrate is obtained; the metal substrate is put into a gold leaching tank containing hydrochloric acid and hydrogen peroxide, and leaching liquid containing gold ions is obtained; zinc powder is used for reducing gold ions in the leaching solution containing the gold ions, and part of solid gold is obtained; further reducing the residual gold ions in the leaching solution containing the gold ions by using oxalic acid to obtain solid gold which is not reduced by the zinc powder; pure gold mud is obtained through acid pickling, water washing and drying of solid gold. According to the method, the zinc powder is used for reducing the gold ions in the leaching solution containing the gold ions, most of the gold ions can be effectively recovered through reduction of the zinc powder, and the gold ions which cannot be completely reduced by the zinc powder are treated through reduction of oxalic acid, so that maximum recovery of the gold ions is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of precious metal refining, in particular to a method for recovering gold from a circuit board. Background Art

[0002] In recent years, with the rapid development of the electronics industry, the number of circuit boards has increased dramatically. These circuit boards contain a large amount of valuable metal resources. Traditional gold recovery methods mainly include pyrometallurgy, hydrometallurgy and physical and mechanical separation. Although pyrometallurgy can effectively recover high-purity gold, it has high energy consumption and serious pollution. Hydrometallurgy extracts gold through dissolution and precipitation of chemical reagents. This method usually requires the use of a large amount of strong acid, strong alkali or cyanide, which poses serious environmental risks and operational safety hazards.

[0003] Existing gold leaching technology relies on hydrochloric acid and hydrogen peroxide, but there are problems with incomplete dissolution of gold ions and interference from other metal ions. The zinc powder reduction method can only partially reduce gold ions, and the efficiency and stability of oxalic acid reduction are affected by many factors. These shortcomings make it challenging to completely reduce gold ions and reduce impurities. Summary of the invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a method for recovering gold from a circuit board to solve the problems of incomplete removal of organic components, low purity of the metal substrate and incomplete reduction of gold ions in the process of gold recovery from the circuit board.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for recovering gold from a circuit board, comprising: preliminarily crushing the circuit board, heating the crushed circuit board to obtain a gold-containing bright board;

[0008] The gold-containing plate was extracted using supercritical fluid extraction technology to separate the dissolved organic components to obtain a pure metal substrate;

[0009] The metal substrate is placed in a gold leaching tank containing hydrochloric acid and hydrogen peroxide to obtain a leaching solution containing gold ions;

[0010] Using zinc powder to reduce gold ions in the gold ion-containing leaching solution to obtain part of the solid gold;

[0011] Then, oxalic acid is used to further reduce the gold ions in the remaining gold ion-containing leaching solution to obtain solid gold that has not been reduced by zinc powder;

[0012] Pure gold mud is obtained by acid washing, water washing and drying of solid gold.

[0013] As a preferred embodiment of the method for recovering gold from a circuit board of the present invention, the circuit board is initially crushed, and the crushed circuit board is heated to obtain a gold-containing bright board, which comprises the following steps:

[0014] The circuit board is initially broken, the broken circuit board is heated, and the temperature and processing time are set. After the heating is completed, the surface components are completely detached, and the separated gold-containing boards are collected.

[0015] As a preferred embodiment of the method for recovering gold from a circuit board of the present invention, the method comprises the following steps: extracting the gold-containing light board using supercritical fluid extraction technology, separating the dissolved organic components to obtain a pure metal substrate,

[0016] Select carbon dioxide as the supercritical fluid solvent, and set the carbon dioxide flow rate and the pressure in the extraction container;

[0017] Place the gold-containing plates evenly in the extraction container, adjust the temperature in the extraction container and set the extraction time, so that the organic matter and impurities are fully dissolved and flow out with the carbon dioxide;

[0018] The extraction efficiency is calculated by the supercritical fluid extraction mathematical model, and the expression is:

[0019]

[0020] Where E(t) is the extraction efficiency at time t, M in (t) is the mass of organic matter input at time t, M out (t) is the mass of the output organic matter at time t, Z is the temperature sensitivity coefficient, T is the temperature during the extraction process, and ΔT is the temperature change;

[0021] After the extraction is completed, the carbon dioxide gasification pressure is reduced, so that the carbon dioxide gradually changes into gas in a supercritical state and takes away the dissolved organic components and impurities, thereby obtaining a pure metal substrate after supercritical fluid extraction.

[0022] As a preferred embodiment of the method for recovering gold from a circuit board of the present invention, the metal substrate is placed in a gold leaching tank containing hydrochloric acid and hydrogen peroxide to obtain a leaching solution containing gold ions, which comprises the following steps:

[0023] Prepare hydrochloric acid solution, add hydrogen peroxide to the hydrochloric acid solution, and add the well-proportioned solution into the gold leaching tank;

[0024] The pure metal substrate obtained after supercritical fluid extraction is evenly placed in the gold immersion tank, and the dissolution rate of gold is calculated. The expression is:

[0025]

[0026] Among them, R Au (t) is the gold dissolution rate at time t, k0 is the maximum dissolution rate of gold ions in the initial state, C Au,0 is the initial gold concentration in the metal substrate, E a is the activation energy, B is the activation energy converted to energy units related to temperature, τ is the absolute temperature, D is the molar concentration of hydrochloric acid, L is the molar concentration of hydrogen peroxide, C Au (t) is the concentration of gold ions in the solution at time t, C Au,∞ is the maximum concentration of gold ions in the solution at the final equilibrium state, and n is the reaction order;

[0027] The undissolved solid residue and the leaching solution containing gold ions are separated by a filter, and the filtered leaching solution is washed to remove residual chemicals and impurities to obtain the leaching solution containing gold ions.

[0028] As a preferred embodiment of the method for recovering gold from a circuit board of the present invention, the method of reducing the gold ions in the gold ion-containing leaching solution with zinc powder to obtain part of the solid gold comprises the following steps:

[0029] Add zinc powder to the gold ion leaching solution, adjust the temperature in the reactor and the pH value of the leaching solution, and slowly pour the gold ion leaching solution into the reactor;

[0030] Calculate the mass of solid gold reduced by gold ions from zinc powder. The expression is:

[0031]

[0032] M Au (t) is the mass of solid gold generated by zinc powder reduction at time t, b is a reaction rate related to the activity of zinc powder, Zn represents the concentration of zinc powder, Au 3+ is the concentration of gold ions in the solution, m is the exponential term of the gold ion concentration, β is a correction coefficient related to the hydrogen ion concentration, H + is the concentration of hydrogen ions in the solution, j is the exponential term of the hydrogen ion concentration, λ is the change of reaction rate with time, and V is the volume of the leachate.

[0033] As a preferred embodiment of the method for recovering gold from a circuit board according to the present invention, the gold ions in the remaining gold ion-containing leaching solution are further reduced with oxalic acid to obtain solid gold that has not been reduced by zinc powder, comprising the following steps:

[0034] Prepare oxalic acid solution, adjust the temperature in the reactor and the pH value of the leaching solution, and slowly pour the leaching solution still containing some gold ions after zinc powder reduction into the reactor;

[0035] The amount of oxalic acid required is calculated based on the gold ion concentration. The remaining gold ions are reduced to solid gold by oxalic acid. The expression is:

[0036]

[0037] Among them, Y Au (t) is the mass of solid gold generated by oxalic acid reduction at time t, K is the initial input amount of oxalic acid, C Au,rem is the residual gold ion concentration, μ is the reaction rate constant, H + is the hydrogen ion concentration in the solution, δ is the inhibition coefficient, n is the reaction order, η is the stirring enhancement factor, S is the stirring speed, θ is the temperature sensitivity coefficient, φ is the oxalic acid particle size distribution correction coefficient, ψ is the reference temperature, ω is the current reaction temperature, O c is the average particle size of oxalic acid.

[0038] As a preferred embodiment of the method for recovering gold from a circuit board of the present invention, the method comprises the following steps: fusing part of the solid gold obtained by reducing zinc powder with the solid gold produced in the further reduction process of oxalic acid to obtain the final total amount of solid gold:

[0039] Put two solid golds into a furnace, and under the protection of inert gas, adjust the temperature in the furnace to melt the two solid golds;

[0040] After melting is completed, it is cooled and taken out to form a uniform total amount of solid gold.

[0041] As a preferred embodiment of the method for recovering gold from a circuit board of the present invention, the method of obtaining pure gold mud by pickling, washing and drying solid gold comprises the following steps: preparing a dilute nitric acid solution, adjusting the temperature in the pickling tank and setting the pickling time, and pouring the finally generated solid gold into the pickling tank;

[0042] Transfer the solid gold after pickling to a water washing tank and add deionized water for washing;

[0043] The washed solid gold is transferred to a drying box to dry the solid gold to obtain gold mud.

[0044] In a second aspect, the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program is executed by the processor, any step of the method for recovering gold from a circuit board as described in the first aspect of the present invention is implemented.

[0045] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the method for recovering gold from a circuit board as described in the first aspect of the present invention is implemented.

[0046] The beneficial effects of the present invention are as follows: by preliminarily heating the circuit board after it is crushed, the surface components are completely detached, and the gold-containing light board is separated; by using supercritical fluid extraction technology to extract the gold-containing light board, supercritical carbon dioxide is used as a solvent to effectively remove organic components without damaging the metal substrate; the combination of hydrochloric acid and hydrogen peroxide effectively dissolves the gold in the metal substrate to form a solution containing gold ions, thereby increasing the dissolution rate of gold; by using zinc powder to reduce the gold ions in the gold-containing ion leaching solution, the zinc powder reduction can effectively recover most of the gold ions; and then by using oxalic acid to reduce the gold ions that cannot be completely reduced by zinc powder, the maximum recovery of the gold ions is ensured; the melting process ensures that the solid gold from the two sources is fully mixed to form a uniform total amount of solid gold; then the impurities remaining on the surface are removed by acid washing, the residual acid solution is removed by water washing, and the drying ensures the drying of the final gold mud. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0048] Figure 1 This is a flow chart of the method for recovering gold from a circuit board in Example 1.

[0049] Figure 2 The present invention is a flow chart of obtaining a pure metal substrate by the method for recovering gold from a circuit board in Example 1. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0051] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0053] Example 1, reference Figure 1 and Figure 2 , which is the first embodiment of the present invention, provides a method for recovering gold from a circuit board, comprising the following steps:

[0054] S1, preliminarily crushing the circuit board, and heating the crushed circuit board to obtain a gold-containing light board, including the following steps:

[0055] The circuit board is preliminarily broken, the broken circuit board is heated, and the temperature and processing time are set. After the heating is completed, the surface components are completely detached, and the separated gold-containing light board is collected;

[0056] Furthermore, when the circuit board is crushed, the particle size of the circuit board after crushing is set to 5-10 mm;

[0057] Set the processing time to 30-60 minutes and the temperature of the heating furnace to 250-350°C;

[0058] The broken circuit board is placed in a heating furnace to make the surface components fall off without damaging the metal substrate.

[0059] S2. Extracting the gold-containing plate using supercritical fluid extraction technology to separate the dissolved organic components to obtain a pure metal substrate includes the following steps:

[0060] Select carbon dioxide as the supercritical fluid solvent, and set the carbon dioxide flow rate and the pressure in the extraction container;

[0061] Place the gold-containing plates evenly in the extraction container, adjust the temperature in the extraction container and set the extraction time, so that the organic matter and impurities are fully dissolved and flow out with the carbon dioxide;

[0062] The extraction efficiency is calculated by the supercritical fluid extraction mathematical model, and the expression is:

[0063]

[0064] Where E(t) is the extraction efficiency at time t, M in (t) is the mass of organic matter input at time t, M out (t) is the mass of the output organic matter at time t, Z is the temperature sensitivity coefficient, T is the temperature during the extraction process, and ΔT is the temperature change;

[0065] After the extraction is completed, the carbon dioxide gasification pressure is reduced, so that the carbon dioxide gradually changes into gas in a supercritical state and takes away the dissolved organic components and impurities, thereby obtaining a pure metal substrate after supercritical fluid extraction.

[0066] Furthermore, carbon dioxide was selected as the supercritical fluid solvent because it is non-toxic, and the flow rate of carbon dioxide was set to 0.5 L / min to ensure that the solvent could fully contact and dissolve the organic components;

[0067] Adjust the pressure in the extraction container to 7.38 MPa, which is the critical pressure of carbon dioxide, to ensure that it is in a supercritical state;

[0068] Place the gold-containing plates evenly in the extraction container to ensure that each piece of material is in full contact with the supercritical fluid;

[0069] Adjust the temperature in the extraction container to 31.1°C, which is the critical temperature of carbon dioxide, to ensure that it is in a supercritical state;

[0070] Set the extraction time to 30 minutes to ensure that organic matter and impurities are fully dissolved and flow out with the carbon dioxide;

[0071] According to the real-time monitoring data, the extraction temperature, pressure and flow rate are adjusted in time to ensure the maximum extraction efficiency. The value range of the extraction efficiency E(t) is [0, 1], where 0 means that no organic matter is extracted at all, and 1 means that all organic matter is completely extracted;

[0072] After the extraction is completed, the pressure is gradually reduced to allow the carbon dioxide to gradually change from a supercritical state to a gaseous state. As the pressure decreases, the solubility of carbon dioxide drops sharply, causing the dissolved organic components and impurities to precipitate. The carbon dioxide gasifies and takes away the dissolved organic components and impurities. Finally, the undissolved solid residue is separated through a filter to obtain a pure metal substrate.

[0073] S3, placing the metal substrate into a gold leaching tank containing hydrochloric acid and hydrogen peroxide to obtain a leaching solution containing gold ions, comprising the following steps:

[0074] Prepare hydrochloric acid solution, add hydrogen peroxide to the hydrochloric acid solution, and add the well-proportioned solution into the gold leaching tank;

[0075] The pure metal substrate obtained after supercritical fluid extraction is evenly placed in the gold immersion tank, and the dissolution rate of gold is calculated. The expression is:

[0076]

[0077] Among them, R Au (t) is the gold dissolution rate at time t, k0 is the maximum dissolution rate of gold ions in the initial state, C Au,0 is the initial gold concentration in the metal substrate, E a is the activation energy, B is the activation energy converted to energy units related to temperature, τ is the absolute temperature, D is the molar concentration of hydrochloric acid, L is the molar concentration of hydrogen peroxide, C Au(t) is the concentration of gold ions in the solution at time t, C Au,∞ is the maximum concentration of gold ions in the solution at the final equilibrium state, and n is the reaction order;

[0078] The undissolved solid residue and the leachate containing gold ions are separated by a filter, and the filtered leachate is washed to remove residual chemicals and impurities to obtain a leachate containing gold ions;

[0079] Furthermore, a hydrochloric acid solution with a concentration of 4 mol / L is prepared, and hydrogen peroxide accounting for 10% of the total volume is added to the hydrochloric acid solution;

[0080] Place the prepared solution in a constant temperature environment at about 25°C, transfer the prepared solution to the gold immersion tank, and ensure that no bubbles are generated;

[0081] Place the pure metal substrate evenly in the gold immersion tank to ensure that the pure metal substrate is in full contact with the solution;

[0082] Calculate the gold dissolution rate and use an online analyzer to monitor the gold ion concentration in the solution in real time to ensure that the dissolution process proceeds as expected;

[0083] Use a high-precision filter to separate the undissolved solid residue and the leaching solution containing gold ions;

[0084] The separated leachate is washed several times to ensure that all residual chemicals and impurities are completely removed;

[0085] Deionized water is used as a washing liquid to ensure that no new impurities are introduced, and the leaching liquid after washing is collected and concentrated to obtain a leaching liquid containing gold ions.

[0086] S4, using zinc powder to reduce the gold ions in the gold ion-containing leaching solution to obtain part of the solid gold comprises the following steps:

[0087] Add zinc powder to the gold ion leaching solution, adjust the temperature in the reactor and the pH value of the leaching solution, and slowly pour the gold ion leaching solution into the reactor;

[0088] Calculate the mass of solid gold generated by gold ions reduced by zinc powder. The expression is:

[0089]

[0090] M Au (t) is the mass of solid gold generated by zinc powder reduction at time t, b is a reaction rate related to the activity of zinc powder, Zn represents the concentration of zinc powder, Au 3+ is the concentration of gold ions in the solution, m is the exponential term of the gold ion concentration, β is a correction coefficient related to the hydrogen ion concentration, H +is the concentration of hydrogen ions in the solution, j is the exponential term of the hydrogen ion concentration, λ is the change of reaction rate with time, and V is the volume of the leachate.

[0091] Furthermore, zinc powder was added to the gold ion-containing leaching solution, the temperature in the reactor was precisely adjusted to 25°C, and the pH value of the leaching solution was adjusted to 1.5;

[0092] Slowly pour the gold ion-containing leaching solution into the reactor through the funnel, ensuring a smooth pouring process to avoid bubbles or splashing;

[0093] Stir the reaction kettle into which the zinc powder-containing gold ion leaching solution is added to ensure that the zinc powder and the gold ions are fully in contact to prevent excessive local concentration;

[0094] The reaction time was set at 60 minutes to ensure that the gold ions were fully reduced to solid gold, and the mass of the solid gold generated by the reduction of zinc powder was calculated.

[0095] S5, further reducing the gold ions in the remaining gold ion-containing leaching solution with oxalic acid to obtain solid gold that has not been reduced by zinc powder, comprising the following steps:

[0096] Prepare oxalic acid solution, adjust the temperature in the reactor and the pH value of the leaching solution, and slowly pour the leaching solution still containing some gold ions after zinc powder reduction into the reactor;

[0097] The amount of oxalic acid required is calculated based on the gold ion concentration. The remaining gold ions are reduced to solid gold by oxalic acid. The expression is:

[0098]

[0099] Among them, Y Au (t) is the mass of solid gold generated by oxalic acid reduction at time t, K is the initial input amount of oxalic acid, C Au,rem is the residual gold ion concentration, μ is the reaction rate constant, H + is the hydrogen ion concentration in the solution, δ is the inhibition coefficient, n is the reaction order, η is the stirring enhancement factor, S is the stirring speed, θ is the temperature sensitivity coefficient, φ is the oxalic acid particle size distribution correction coefficient, ψ is the reference temperature, ω is the current reaction temperature, O c is the average particle size of oxalic acid;

[0100] Furthermore, an oxalic acid solution with a concentration of 0.5 mol / L was prepared, the temperature in the reactor was accurately adjusted to 80°C, and the pH value of the leaching solution was adjusted to 1.5;

[0101] The leaching solution that still contains some gold ions after zinc powder reduction is slowly poured into the reactor, and it is calculated that the remaining gold ions are reduced to solid gold by oxalic acid.

[0102] S6, fusing part of the solid gold obtained by reducing zinc powder with the solid gold produced in the further reduction process of oxalic acid to obtain the final total amount of solid gold, comprising the following steps:

[0103] Put two solid golds into a furnace, and under the protection of inert gas, adjust the temperature in the furnace to melt the two solid golds;

[0104] After melting is completed, it is cooled and taken out to form a uniform total amount of solid gold;

[0105] Furthermore, a resistance furnace was selected to melt the two solid golds, and high-purity argon was used as a shielding gas to prevent the gold from reacting with oxygen in the air during the melting process;

[0106] Weigh and record the mass of the solid gold obtained by zinc powder reduction and the solid gold produced in the oxalic acid reduction process, and put them into a refractory crucible in a resistance furnace;

[0107] Gradually raise the temperature of the resistance furnace to about 500°C for preheating to ensure that the moisture and volatile substances inside the material are completely evaporated;

[0108] Adjust the temperature of the resistance furnace to the melting point of gold, 1064.18°C, to ensure that the two solid golds are completely melted;

[0109] Stirring is performed during the melting process to promote uniform mixing of the two solid golds;

[0110] Set the resistance furnace time to 30 minutes to ensure that the two solid golds are fully melted and completely fused. After the furnace cools to a safe temperature, take out the molten solid gold.

[0111] S7, obtaining pure gold mud by pickling, washing and drying the solid gold includes the following steps: preparing a dilute nitric acid solution, adjusting the temperature in the pickling tank and setting the pickling time, and pouring the finally generated solid gold into the pickling tank;

[0112] Transfer the solid gold after pickling to a water washing tank and add deionized water for washing;

[0113] The washed solid gold is transferred to a drying box to dry the solid gold to obtain gold mud;

[0114] Furthermore, a dilute nitric acid solution with a concentration of 6 mol / L is prepared, and the temperature in the pickling tank is adjusted to 30-40°C, which is the optimal temperature range for dilute nitric acid to dissolve impurities. The pickling time is set to 20-30 minutes, and the solid gold after molten fusion is poured into the pickling tank to ensure that each piece of material can fully contact with the acid solution;

[0115] The solid gold after pickling is transferred from the pickling tank to the water washing tank and washed with water for multiple times. After each washing, the deionized water in the water washing tank is replaced in time to ensure the washing effect;

[0116] Use a conductivity meter to test the water quality after washing to ensure that its conductivity is close to the standard of deionized water, indicating that the residual chemicals have been completely removed;

[0117] Transfer the washed solid gold to a preheated drying oven to ensure that the material is evenly distributed to avoid accumulation;

[0118] Adjust the drying box temperature to 80-100°C, the optimal temperature range for removing moisture without damaging gold, to ensure drying efficiency and safety;

[0119] Set the drying time to 2-3 hours to ensure that the water is completely evaporated to obtain the dried gold mud.

[0120] This embodiment also provides a computer device, which is suitable for the method of recovering gold from a circuit board, and includes: a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to implement the method of recovering gold from a circuit board as proposed in the above embodiment.

[0121] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0122] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method for recovering gold from a circuit board as proposed in the above embodiment is implemented; the storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (Static Random Access Memory, referred to as SRAM), electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, referred to as EEPROM), erasable programmable read-only memory (Erasable Programmable Read Only Memory, referred to as EPROM), programmable read-only memory (Programmable Red-Only Memory, referred to as PROM), read-only memory (Read-Only Memory, referred to as ROM), magnetic storage, flash memory, magnetic disk or optical disk.

[0123] In summary, the present invention comprises the following steps: preliminarily heating the crushed circuit board to completely remove the surface components and separate the gold-containing light board; extracting the gold-containing light board by using supercritical fluid extraction technology, using supercritical carbon dioxide as a solvent to effectively remove organic components without damaging the metal substrate; effectively dissolving the gold in the metal substrate by a combination of hydrochloric acid and hydrogen peroxide to form a solution containing gold ions, thereby increasing the dissolution rate of gold; reducing the gold ions in the gold-containing ion leaching solution by using zinc powder, and the zinc powder reduction can effectively recover most of the gold ions; then reducing the gold ions by oxalic acid to process the gold ions that cannot be completely reduced by zinc powder, thereby ensuring the maximum recovery of the gold ions; the melting process ensures that the solid gold from the two sources is fully mixed to form a uniform total amount of solid gold; then removing the impurities remaining on the surface by pickling, removing the residual acid by water washing, and ensuring the drying of the final gold mud by drying.

[0124] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for recovering gold from a circuit board, characterized in that: include, The circuit board is preliminarily broken, and the broken circuit board is heated to obtain a gold-containing board; The gold-containing plate was extracted using supercritical fluid extraction technology to separate the dissolved organic components to obtain a pure metal substrate; The metal substrate is placed in a gold leaching tank containing hydrochloric acid and hydrogen peroxide to obtain a leaching solution containing gold ions; Using zinc powder to reduce gold ions in the gold ion-containing leaching solution to obtain part of the solid gold; Then, oxalic acid is used to further reduce the gold ions in the remaining gold ion-containing leaching solution to obtain solid gold that has not been reduced by zinc powder; Pure gold mud is obtained by acid washing, water washing and drying of solid gold.

2. The method for recovering gold from a circuit board according to claim 1, characterized in that: The circuit board is preliminarily broken, and the broken circuit board is heated to obtain a gold-containing light board, which includes the following steps: The circuit board is initially broken, the broken circuit board is heated, and the temperature and processing time are set. After the heating is completed, the surface components are completely detached, and the separated gold-containing boards are collected.

3. The method for recovering gold from a circuit board as claimed in claim 2, characterized in that: The process of extracting the gold-containing plate using supercritical fluid extraction technology to separate the dissolved organic components to obtain a pure metal substrate includes the following steps: Select carbon dioxide as the supercritical fluid solvent, and set the carbon dioxide flow rate and the pressure in the extraction container; Place the gold-containing plates evenly in the extraction container, adjust the temperature in the extraction container and set the extraction time, so that the organic matter and impurities are fully dissolved and flow out with the carbon dioxide; The extraction efficiency is calculated by the supercritical fluid extraction mathematical model, and the expression is: Where E(t) is the extraction efficiency at time t, M in (t) is the mass of the input organic matter at time t, M out (t) is the mass of the output organic matter at time t, Z is the temperature sensitivity coefficient, T is the temperature during the extraction process, and ΔT is the temperature change; After the extraction is completed, the carbon dioxide gasification pressure is reduced, so that the carbon dioxide gradually changes into gas in a supercritical state and takes away the dissolved organic components and impurities, thereby obtaining a pure metal substrate after supercritical fluid extraction.

4. The method for recovering gold from a circuit board as claimed in claim 3, characterized in that: Placing the metal substrate into a gold leaching tank containing hydrochloric acid and hydrogen peroxide to obtain a leaching solution containing gold ions comprises the following steps: Prepare hydrochloric acid solution, add hydrogen peroxide to the hydrochloric acid solution, and add the well-proportioned solution into the gold leaching tank; The pure metal substrate obtained after supercritical fluid extraction is evenly placed in the gold immersion tank, and the dissolution rate of gold is calculated. The expression is: Among them, R Au (t) is the gold dissolution rate at time t, k0 is the maximum dissolution rate of gold ions in the initial state, C Au,0 is the initial gold concentration in the metal substrate, E a is the activation energy, B is the activation energy converted to energy units related to temperature, τ is the absolute temperature, D is the molar concentration of hydrochloric acid, L is the molar concentration of hydrogen peroxide, C Au (t) is the concentration of gold ions in the solution at time t, C Au,∞ is the maximum concentration of gold ions in the solution at the final equilibrium state, and n is the reaction order; The undissolved solid residue and the leaching solution containing gold ions are separated by a filter, and the filtered leaching solution is washed to remove residual chemicals and impurities to obtain the leaching solution containing gold ions.

5. The method for recovering gold from a circuit board as claimed in claim 4, characterized in that: Using zinc powder to reduce gold ions in a gold ion-containing leaching solution to obtain part of solid gold comprises the following steps: Add zinc powder to the gold ion leaching solution, adjust the temperature in the reactor and the pH value of the leaching solution, and slowly pour the gold ion leaching solution into the reactor; Calculate the mass of solid gold generated by gold ions reduced by zinc powder. The expression is: Among them, M Au (t) is the mass of solid gold generated by zinc powder reduction at time t, b is the reaction rate related to the activity of zinc powder, Zn represents the concentration of zinc powder, Au 3+ is the concentration of gold ions in the solution, m is the exponential term of the gold ion concentration, β is the correction coefficient related to the hydrogen ion concentration, H + is the concentration of hydrogen ions in the solution, j is the exponential term of the hydrogen ion concentration, λ is the change of reaction rate with time, and V is the volume of the leachate.

6. The method for recovering gold from a circuit board as claimed in claim 5, characterized in that: The gold ions in the remaining gold ion-containing leaching solution are further reduced with oxalic acid to obtain solid gold that has not been reduced by zinc powder, comprising the following steps: Prepare oxalic acid solution, adjust the temperature in the reactor and the pH value of the leaching solution, and slowly pour the leaching solution still containing some gold ions after zinc powder reduction into the reactor; The amount of oxalic acid required is calculated based on the gold ion concentration. The remaining gold ions are reduced to solid gold by oxalic acid. The expression is: Among them, Y Au (t) is the mass of solid gold generated by oxalic acid reduction at time t, K is the initial input amount of oxalic acid, C Au,rem is the residual gold ion concentration, μ is the reaction rate constant, H + is the hydrogen ion concentration in the solution, δ is the inhibition coefficient, n is the reaction order, η is the stirring enhancement factor, S is the stirring speed, θ is the temperature sensitivity coefficient, φ is the oxalic acid particle size distribution correction coefficient, ψ is the reference temperature, ω is the current reaction temperature, O c is the average particle size of oxalic acid.

7. The method for recovering gold from a circuit board as claimed in claim 6, characterized in that: The solid gold obtained by reducing zinc powder and the solid gold produced by further reducing with oxalic acid are fused to obtain the final total amount of solid gold, comprising the following steps: Put two solid golds into a furnace, and under the protection of inert gas, adjust the temperature in the furnace to melt the two solid golds; After melting is completed, it is cooled and taken out to form a uniform total amount of solid gold.

8. The method for recovering gold from a circuit board as claimed in claim 7, characterized in that: The process of obtaining pure gold mud by pickling, washing and drying solid gold comprises the following steps: preparing a dilute nitric acid solution, adjusting the temperature in the pickling tank and setting the pickling time, and pouring the finally generated solid gold into the pickling tank; The solid gold after pickling is transferred to a water washing tank and washed with deionized water; The washed solid gold is transferred to a drying box to dry the solid gold to obtain gold mud.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for recovering gold from a circuit board according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for recovering gold from a circuit board according to any one of claims 1 to 8 are implemented.

Images