Method for recycling waste etching liquid containing copper and iron

Abstract

The invention provides a copper and iron-containing etching waste liquid recovery treatment method, which comprises: adding a copper and iron-containing etching waste liquid into a heated alkali liquid, maintaining the temperature, aging after the reaction is completed, cooling, and carrying out solid-liquid separation to obtain a copper and iron-containing mixed solid and a first separation liquid; performing bipolar membrane treatment on the first separation liquid to obtain a caustic alkali solution and a hydrochloric acid solution; neutralizing a hydrochloric acid solution, precipitating, and calcining a precipitated solid to obtain a calcined residue and tail gas; and the calcination tail gas is used for calcination decomposition and reduction of the copper and iron-containing mixed solid, a copper and iron mixed solid is obtained, and copper and iron are obtained through magnetic separation treatment and separation. According to the method, copper and iron ions form precipitates in an alkalization mode, then acid and alkali solutions are formed through bipolar membrane treatment, and through multi-step treatment of the acid solution and calcination of the precipitates containing copper and iron, full recovery and utilization of the etching waste liquid are achieved, and the treatment difficulty and danger are reduced; the method is simple and convenient to operate, the treatment cost is reduced, and secondary pollution is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of etching liquid treatment, and relates to a method for recycling etching waste liquid containing copper and iron. Background Art

[0002] As a basic component of electronic products, the production process of printed circuit boards includes important processes such as printed circuits and etching circuits. The etching process will produce a large amount of etching waste liquid. The copper content in the etching waste liquid is relatively high, and depending on the composition of the etching liquid used, it will also contain other components. For example, the etching waste liquid formed after the circuit board is treated with ferric chloride solution will also contain iron ions, hydrogen ions, etc. If the etching waste liquid is not handled properly, it will not only cause serious pollution to the environment, but also waste valuable resources. Therefore, the selection of efficient and appropriate technical methods to treat copper and iron etching waste liquid is the key to achieving waste liquid treatment and efficient utilization.

[0003] At present, the methods that can be used to treat etching waste liquid include neutralization precipitation method, electrolytic reduction method, etc. Among them, the neutralization precipitation method is to use alkaline solution to convert copper ions into copper oxide mud. This method consumes a lot of reagents and a large amount of tail water, and other components are not recycled, especially ferric chloride etching waste liquid, which will cause the copper mud recovered by neutralization to be of insufficient grade, and the value of resource utilization is greatly limited; the electrolytic reduction method is to extract the copper in the waste liquid by electrolysis, but the energy consumption is high, and the treatment difficulty is increased for etching waste liquid containing multiple metal ions.

[0004] For copper-containing etching waste liquid containing ferric chloride, there is also a method of introducing iron powder reduction, so that elemental copper can be recovered from the etching waste liquid. However, there is free hydrochloric acid in the etching waste liquid, which causes hydrogen to be generated during the reduction process. If the operation is improper, the iron powder fails to react in time and aggregates, which can easily cause material overflow or even explosion, posing certain safety hazards. Therefore, the treatment of copper and iron etching waste liquid still needs to be optimized and improved.

[0005] CN 108947063A discloses a process for resource-based treatment of acidic etching waste liquid and alkaline etching waste liquid. The method selects acidic etching waste liquid and alkaline etching waste liquid to mix, adds alkali liquor at the same time, and performs filter pressing after adjusting pH value to obtain copper-containing sludge and primary filtrate respectively. A copper removal agent and a flocculant are respectively added to the primary filtrate for flocculation and sedimentation, and then filtered and separated to obtain copper-containing precipitate and secondary filtrate. The secondary filtrate is filtered by a filter element to obtain a particle-free tertiary filtrate, the pH value of the tertiary filtrate is adjusted, and then the cation exchange resin is passed to obtain a quaternary filtrate with a copper content of less than 1ppm. The quaternary filtrate is subjected to reduced pressure distillation to obtain sodium chloride crystals and a primary mother liquor, and the primary mother liquor is pumped into a constant temperature crystallizer to obtain ammonium chloride crystals and ear secondary mother liquor respectively. Although the method can treat acidic and alkaline etching waste liquids together, it does not treat ferric chloride etching waste liquid, that is, it does not involve the separation of iron and copper after co-sedimentation, nor does it involve the recovery and conversion of acid or alkali.

[0006] CN 117661052A discloses a method for copper regeneration from heat sink etching waste liquid, the method comprising: uniformly mixing heat sink etching waste liquid and electrolytic aid to obtain electrolyte; passing ferrous chloride solution and electrolyte to be electrolyzed into the anode chamber and cathode chamber of an electrolytic cell respectively for electrolytic treatment, the regenerated ferric chloride etching solution obtained in the anode chamber is reused in etching, copper and ferrous chloride solution are obtained in the cathode chamber, and the ferrous chloride solution is used in the electrolytic treatment of the anode chamber. The method electrolytically treats copper-containing etching waste liquid, and uses ferrous chloride as the anode chamber solution, rather than recovering copper and iron together, and does not involve the recovery and treatment of non-copper components in the etching waste liquid, and the value of resource utilization is low.

[0007] In summary, for the recycling and treatment of copper- and iron-containing etching waste liquid, a suitable combined process is required so that the copper and iron components can be recovered and separated together, and the remaining components after metal recovery can also be recycled, with high resource utilization value and no secondary pollution. Summary of the invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for recycling and treating etching waste liquid containing copper and iron. The method converts copper and iron in the etching waste liquid into precipitates by alkalization, and recovers acid and alkali solutions from the remaining solution through bipolar membrane treatment, and uses the products in the acid solution recovery process to reduce the copper and iron precipitates to copper and iron elements. Through the above treatment, the resource recovery and treatment of each component in the etching waste liquid can be effectively realized, and secondary pollution is generated during the treatment process.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for recycling copper- and iron-containing etching waste liquid, the method comprising the following steps:

[0011] (1) adding the copper- and iron-containing etching waste liquid to the heated alkali solution, maintaining the temperature, aging after the reaction is completed, and then separating the solid and the liquid after cooling to obtain a copper- and iron-containing mixed solid and a first separated liquid;

[0012] (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment to obtain a caustic soda solution and a hydrochloric acid solution;

[0013] (3) neutralizing the hydrochloric acid solution obtained in step (2) and precipitating the solution, and calcining the precipitated solid after solid-liquid separation to obtain a calcination residue and tail gas;

[0014] (4) The tail gas generated by the calcination in step (3) is used for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1) to obtain a copper-iron mixed solid, which is then subjected to magnetic separation to separate metallic copper and metallic iron.

[0015] In the present invention, different treatment processes need to be selected for the treatment of etching waste liquid according to the different types and compositions thereof. The copper- and iron-containing etching waste liquid in the present invention is obtained after etching with a ferric chloride solution as an etching solution. According to the composition characteristics thereof, a neutralization and alkalization method is first adopted to solidify free copper and iron ions to form copper- and iron-containing precipitations, and the remaining solution is treated by a bipolar membrane to form an acid and alkaline solution, and then the acid solution is neutralized, precipitated, calcined and other treatments are carried out. The tail gas generated is used for calcination, decomposition and reduction of the copper- and iron-containing precipitations, so as to obtain copper and iron metal elements, and then the metal copper and iron are respectively recovered through magnetic separation, so as to achieve full recovery and utilization of various components in the etching waste liquid, and reduce the difficulty and danger of etching waste liquid treatment. The method is simple to operate, the intermediate product can be recycled, the treatment cost is reduced, and no secondary pollution is generated.

[0016] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0017] As a preferred technical solution of the present invention, the copper- and iron-containing etching waste liquid in step (1) is an etching waste liquid obtained by etching a ferric chloride solution, which contains ferric chloride, cupric chloride and hydrochloric acid.

[0018] Preferably, the copper content in the copper-containing and iron-containing etching waste liquid in step (1) is 50-60 g / L, for example, 50 g / L, 52 g / L, 54 g / L, 55 g / L, 56 g / L, 58 g / L or 60 g / L, etc., the iron content is 20-30 g / L, for example, 20 g / L, 22 g / L, 24 g / L, 25 g / L, 26 g / L, 28 g / L or 30 g / L, etc., and the chloride ion content is 100-200 g / L, for example, 10 0g / L, 120g / L, 135g / L, 150g / L, 160g / L, 180g / L or 200g / L, etc., and the free acid content is 1-2mol / L, for example, 1mol / L, 1.2mol / L, 1.4mol / L, 1.5mol / L, 1.6mol / L, 1.8mol / L or 2mol / L, etc.; but are not limited to the listed values, and other unlisted values ​​within the respective numerical ranges are equally applicable.

[0019] In the present invention, according to the source of the copper- and iron-containing etching waste liquid, divalent iron ions are contained therein when it is initially obtained. However, the etching waste liquid in the present invention has been stored for a long time before being treated and has been exposed to air for a long time, and the divalent iron has been basically oxidized, so ferrous chloride is not mentioned in its components.

[0020] Preferably, the alkali solution in step (1) comprises an alkali metal carbonate solution and / or an alkali metal bicarbonate solution, preferably comprises any one of sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate, or a combination of at least two thereof. Typical but non-limiting examples of the combination include: a combination of sodium carbonate and sodium bicarbonate, a combination of potassium carbonate and potassium bicarbonate, a combination of sodium carbonate, sodium bicarbonate and potassium carbonate, a combination of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate, etc.

[0021] Preferably, the concentration of the alkali solution in step (1) is 1 to 2 mol / L, for example, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.8 mol / L or 2 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] In the present invention, for the precipitation of copper and iron ions, according to the ion characteristics, the pH value required for converting copper ions into basic copper carbonate precipitation is relatively small, and is closer to the pH value of precipitation of iron hydroxide. If copper hydroxide is precipitated, the required pH value is relatively large, and it can be completely precipitated only when the pH is above 10, and the required amount of alkali solution is relatively large, and the cost is relatively high. Therefore, the present invention combines process and cost considerations and adopts carbonate solution as neutralizing alkali solution.

[0023] As a preferred technical solution of the present invention, the copper- and iron-containing etching waste liquid in step (1) is slowly and uniformly added into the alkaline solution.

[0024] Preferably, the rate of adding the copper- and iron-containing etching waste liquid is 70 to 100 mL / s, for example, 70 mL / s, 75 mL / s, 80 mL / s, 85 mL / s, 90 mL / s, 95 mL / s or 100 mL / s, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In the present invention, the method of gradually adding the etching waste liquid into the alkaline solution is adopted to make it easier to control the reaction pH value. At the same time, by adjusting the constant speed of adding the etching waste liquid, the mixed powder formed by the precipitation can be made loose and dispersed, which is beneficial to the subsequent washing and separation.

[0026] Preferably, the alkali solution in step (1) is heated in advance to 65-75°C, for example, 65°C, 66°C, 68°C, 70°C, 72°C, 74°C or 75°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, during the reaction in step (1), the temperature is maintained at 65-75°C, for example, 65°C, 66°C, 68°C, 70°C, 72°C, 74°C or 75°C, and the reaction is terminated when the pH value drops to 6-7, for example, 6, 6.2, 6.4, 6.6, 6.8 or 7, but is not limited to the listed values, and other values ​​not listed within the respective numerical ranges are also applicable.

[0028] In the present invention, the reaction temperature is one of the important factors affecting the precipitation of copper and iron ions. If the reaction temperature is low, the mixed solid formed by the precipitation will become sticky, affecting the speed of solid-liquid separation and making washing difficult. If the reaction temperature is high, the mixed solid formed by the precipitation will have uneven particle size and color distribution, and the filtrate will easily become turbid during solid-liquid separation, requiring repeated circulation and purification. At the same time, the high temperature will prolong the aging cooling time, affecting the treatment rate of the etching waste liquid.

[0029] As a preferred technical solution of the present invention, the reaction temperature is maintained during the aging in step (1), and the aging time is 0.5 to 1 h, for example, 0.5 h, 0.6 h, 0.7 h, 0.75 h, 0.8 h, 0.9 h or 1 h, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, step (1) is cooling to room temperature.

[0031] Preferably, the solid-liquid separation in step (1) comprises filtration separation, preferably suction filtration separation.

[0032] Preferably, the copper-iron mixed solid in step (1) is a mixed solid of basic copper carbonate and ferric hydroxide.

[0033] Preferably, the copper-iron mixed solid in step (1) is slurried and washed with water, and then after solid-liquid separation, the washing water is incorporated into the first separation liquid.

[0034] Preferably, the solid-liquid mass ratio of the pulping washing is 1:(1-1.5), such as 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, the pulping and washing time is 1 to 2 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.75 hours, 1.9 hours or 2 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] As a preferred technical solution of the present invention, the bipolar membrane treatment in step (2) uses a bipolar membrane in combination with an anion-cation membrane, and the bipolar membrane is an anion-cation composite membrane.

[0037] In the present invention, the bipolar membrane adopts an anion-cation composite membrane, the anode side is composed of an acid chamber composed of a composite membrane and an anion membrane, the cathode side is composed of an alkali chamber composed of a composite membrane and a cation membrane, and the middle position adopts a plurality of anion membranes and cation membranes in sequence to form a salt chamber.

[0038] Preferably, direct current is applied during the bipolar membrane treatment in step (2).

[0039] Preferably, the voltage of the bipolar membrane treatment in step (2) is 8 to 12 V, for example 8 V, 8.5 V, 9 V, 9.5 V, 10 V, 10.5 V, 11 V, 11.5 V or 12 V, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the current of the bipolar membrane treatment in step (2) is 2.5 to 3.5 A, for example, 2.5 A, 2.6 A, 2.8 A, 3 A, 3.2 A, 3.4 A or 3.5 A, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the temperature of the bipolar membrane treatment in step (2) is 20-35°C, for example, 20°C, 22°C, 25°C, 27°C, 30°C, 32°C or 35°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] Preferably, the caustic soda solution in step (2) comprises sodium hydroxide solution or potassium hydroxide solution.

[0043] As a preferred technical solution of the present invention, the reagent used for neutralization in step (3) includes calcium oxide and / or calcium hydroxide.

[0044] Preferably, the neutralization endpoint pH in step (3) is 5 to 6, such as 5, 5.2, 5.4, 5.5, 5.6, 5.8 or 6, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0045] Preferably, the reagent used for the precipitation in step (3) comprises oxalate, preferably sodium oxalate or potassium oxalate.

[0046] Preferably, the precipitation time in step (3) is 2 to 4 h, for example 2 h, 2.25 h, 2.5 h, 2.75 h, 3 h, 3.25 h, 3.5 h, 3.75 h or 4 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] Preferably, the solid-liquid separation in step (3) comprises filtration separation, preferably suction filtration separation.

[0048] Preferably, the solid-liquid separation in step (3) obtains a solid precipitate and a second separated liquid, and the solid precipitate comprises calcium oxalate solid.

[0049] Preferably, the solid precipitate in step (3) is slurried and washed with water, and after solid-liquid separation, the washing water is incorporated into the second separation liquid, and the second separation liquid is incorporated into the first separation liquid for recycling.

[0050] Preferably, the solid-liquid mass ratio of the pulping washing is 1:(1.5-2), such as 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] Preferably, the pulping and washing time is 2 to 3 hours, for example 2 hours, 2.2 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] As a preferred technical solution of the present invention, the calcination temperature in step (3) is 350-450°C, for example, 350°C, 360°C, 380°C, 400°C, 420°C, 440°C or 450°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] Preferably, the calcination time in step (3) is 3 to 5 h, for example 3 h, 3.25 h, 3.5 h, 3.75 h, 4 h, 4.25 h, 4.5 h, 4.75 h or 5 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] Preferably, the calcined residue in step (3) comprises calcium oxide, and the calcium oxide is returned as a neutralizing agent for the hydrochloric acid solution.

[0055] In the present invention, the hydrochloric acid solution undergoes neutralization, oxalate precipitation conversion and precipitate calcination treatment, and the intermediate products formed in the process can be transferred to the process system for recycling. The calcination tail gas includes carbon monoxide and carbon dioxide, which can be used for calcination, decomposition and reduction of copper-iron mixed solids.

[0056] As a preferred technical solution of the present invention, the tail gas in step (4) includes carbon dioxide and carbon monoxide.

[0057] Preferably, the temperature of the calcination, decomposition and reduction in step (4) is 700-800°C, for example, 700°C, 720°C, 740°C, 750°C, 760°C, 780°C or 800°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable; the time is 5-7h, for example, 5h, 5.25h, 5.5h, 5.75h, 6h, 6.25h, 6.5h, 6.75h or 7h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0058] Preferably, during the calcination and decomposition in step (4), basic copper carbonate decomposes into copper oxide, and iron hydroxide decomposes into iron oxide.

[0059] Preferably, during the calcination reduction in step (4), carbon monoxide is used as a reducing agent, copper oxide is reduced to copper, and iron oxide is reduced to iron.

[0060] Preferably, the tail gas generated during the calcination, decomposition and reduction process in step (4) is absorbed by the caustic soda solution in step (2) and then returned to step (1) for use as alkaline solution.

[0061] As a preferred technical solution of the present invention, the frequency of the magnetic separation treatment in step (4) is 20 to 50 Hz, for example, 20 Hz, 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz or 50 Hz, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0062] Preferably, the gap of the magnetic separation treatment in step (4) is 15 to 25 mm, for example 15 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm or 25 mm, but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable. The gap of the magnetic separation treatment can be regarded as the particle size of the mixed solids separated by the magnetic separation equipment.

[0063] Preferably, the magnetic declination angle of the magnetic separation treatment in step (4) is 5 to 20 degrees, for example, 5 degrees, 8 degrees, 10 degrees, 12 degrees, 15 degrees, 18 degrees or 20 degrees, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0064] As a preferred technical solution of the present invention, the method comprises the following steps:

[0065] (1) slowly and uniformly adding copper- and iron-containing etching waste liquid to the heated alkali solution, wherein the copper- and iron-containing etching waste liquid is an etching waste liquid obtained by etching a ferric chloride solution, and contains ferric chloride, cupric chloride and hydrochloric acid, wherein the copper content is 50-60 g / L, the iron content is 20-30 g / L, the chloride ion content is 100-200 g / L, and the free acid content is 1-2 mol / L. The alkali solution includes an alkali metal carbonate solution and / or an alkali metal bicarbonate solution, and the concentration of the alkali solution is 1-2 mol / L. The rate of adding the copper- and iron-containing etching waste liquid is 70-100 mL / s , the alkali solution is heated to 65-75°C in advance, the temperature is maintained during the reaction, the reaction is terminated after the pH value drops to 6-7, and then aging is performed, the reaction temperature is maintained during the aging, the aging time is 0.5-1h, and then the solid-liquid separation is performed after cooling to room temperature, the solid-liquid separation includes filtration separation, and a copper-iron mixed solid and a first separated liquid are obtained; the copper-iron mixed solid is a mixed solid of basic copper carbonate and ferric hydroxide, water is added for pulping and washing, the solid-liquid mass ratio of the pulping and washing is 1:(1-1.5), the time is 1-2h, and after solid-liquid separation, the washing water is incorporated into the first separated liquid;

[0066] (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment, wherein the bipolar membrane and anion and cation membranes are used in combination, wherein the bipolar membrane is an anion and cation composite membrane, and direct current is applied during the bipolar membrane treatment, wherein the voltage is 8 to 12 V and the current is 2.5 to 3.5 A, and the temperature of the bipolar membrane treatment is 20 to 35° C., to obtain a caustic solution and a hydrochloric acid solution, wherein the caustic solution comprises a sodium hydroxide solution or a potassium hydroxide solution;

[0067] (3) neutralizing the hydrochloric acid solution obtained in step (2) and then precipitating, wherein the reagent used for the neutralization comprises calcium oxide and / or calcium hydroxide, the neutralization end point pH is 5-6, the reagent used for the precipitation comprises oxalate, the precipitation time is 2-4 hours, and after solid-liquid separation, a solid precipitate and a second separated liquid are obtained, wherein the solid precipitate comprises calcium oxalate solid, the solid precipitate is pulped and washed with water, the solid-liquid mass ratio of the pulping and washing is 1:(1.5-2), the time is 2-3 hours, and after solid-liquid separation, the washing water is incorporated into the second separated liquid, and the second separated liquid is incorporated into the first separated liquid for recycling; and then the precipitated solid is calcined, the calcination temperature is 350-450° C., the time is 3-5 hours, and a calcination residue and tail gas are obtained, wherein the calcination residue comprises calcium oxide, and the calcium oxide is returned as a neutralizing reagent for the hydrochloric acid solution;

[0068] (4) using the tail gas generated by the calcination in step (3) for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1), wherein the tail gas includes carbon dioxide and carbon monoxide, and the temperature of the calcination, decomposition and reduction is 700-800° C. and the time is 5-7 hours; during the calcination and decomposition, basic copper carbonate is decomposed into copper oxide, and iron hydroxide is decomposed into iron oxide; during the calcination and reduction, carbon monoxide is used as a reducing agent, and copper oxide is reduced to copper and iron oxide is reduced to iron, thereby obtaining a copper-iron mixed solid; the tail gas generated during the calcination, decomposition and reduction process is absorbed by the caustic soda solution in step (2), and then returned to step (1) for use as alkaline solution; the copper-iron mixed solid is then subjected to magnetic separation treatment, and the frequency of the magnetic separation treatment is 20-50 Hz, the gap is 15-25 mm, and the magnetic declination is 5-20 degrees, so as to separate metallic copper and metallic iron.

[0069] Compared with the prior art, the present invention has the following beneficial effects:

[0070] (1) The method of the present invention is based on the composition characteristics of the copper- and iron-containing etching waste liquid. The free copper and iron ions are firstly solidified by neutralization and alkalization to form copper- and iron-containing precipitates, and the remaining solution is treated by bipolar membrane to form an acid and alkaline solution. The acid solution is then treated by neutralization, precipitation, calcination, etc. The tail gas generated is used for calcination, decomposition and reduction of the copper- and iron-containing precipitates, thereby obtaining copper and iron metal elements. The metallic copper and iron are then recovered by magnetic separation, thereby achieving full recovery and utilization of various components in the etching waste liquid and reducing the difficulty and danger of etching waste liquid treatment.

[0071] (2) The method of the present invention is easy to operate, the intermediate product can be recycled, the processing cost is reduced, and no secondary pollution is generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a process flow diagram of the method for recycling and treating copper- and iron-containing etching waste liquid provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0073] In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0074] The specific implementation method of the present invention provides a method for recycling copper and iron-containing etching waste liquid, which comprises the following steps:

[0075] (1) adding the copper- and iron-containing etching waste liquid to the heated alkali solution, maintaining the temperature, aging after the reaction is completed, and then separating the solid and the liquid after cooling to obtain a copper- and iron-containing mixed solid and a first separated liquid;

[0076] (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment to obtain a caustic soda solution and a hydrochloric acid solution;

[0077] (3) neutralizing the hydrochloric acid solution obtained in step (2) and precipitating the solution, and calcining the precipitated solid after solid-liquid separation to obtain a calcination residue and tail gas;

[0078] (4) The tail gas generated by the calcination in step (3) is used for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1) to obtain a copper-iron mixed solid, which is then subjected to magnetic separation to separate metallic copper and metallic iron.

[0079] The following are typical but non-limiting embodiments of the present invention:

[0080] Embodiment 1:

[0081] This embodiment provides a method for recycling copper and iron-containing etching waste liquid. The process flow chart of the method is as follows: Figure 1 As shown, the following steps are included:

[0082] (1) slowly and uniformly adding copper-containing and iron-containing etching waste liquid to the heated alkali solution, wherein the copper-containing and iron-containing etching waste liquid is an etching waste liquid obtained by etching a ferric chloride solution, and contains ferric chloride, cupric chloride and hydrochloric acid, wherein the copper content is 55 g / L, the iron content is 25 g / L, the chloride ion content is 160 g / L, and the free acid content is 1.5 mol / L. The alkali solution is a sodium carbonate solution, and the concentration of the alkali solution is 1 mol / L. The rate at which the copper-containing and iron-containing etching waste liquid is added is 70 mL / s. The alkali solution The mixture is heated to 65° C. in advance, stirred and maintained at a temperature during the reaction, and the reaction is terminated after the pH value drops to 6, and then aged, wherein the reaction temperature is maintained during the aging, and the aging time is 0.5 h. The mixture is then cooled to room temperature and filtered to obtain a copper-iron mixed solid and a first separated liquid. The copper-iron mixed solid is a mixed solid of basic copper carbonate and ferric hydroxide, and water is added for pulping and washing, wherein the solid-liquid mass ratio of the pulping and washing is 1:1, and the time is 1 h. After separation by filtration, the washing water is incorporated into the first separated liquid.

[0083] (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment, wherein the bipolar membrane and anionic and cationic membranes are used in combination, wherein the bipolar membrane is an anionic and cationic composite membrane, and direct current is applied during the bipolar membrane treatment, wherein the voltage is 10 V and the current is 3.0 A, and the temperature of the bipolar membrane treatment is 25° C., to obtain a sodium hydroxide solution and a hydrochloric acid solution;

[0084] (3) neutralizing the hydrochloric acid solution obtained in step (2) and then precipitating, wherein the reagent used for the neutralization is calcium oxide, the neutralization endpoint pH is 5, the reagent used for the precipitation is sodium oxalate, the precipitation time is 2 hours, and after suction filtration and separation, a solid precipitate and a second separation liquid are obtained, wherein the solid precipitate is calcium oxalate solid, the solid precipitate is pulped and washed with water, the solid-liquid mass ratio of the pulping and washing is 1:1.5, the time is 2 hours, and after filtration and separation, the washing water is incorporated into the second separation liquid, and the second separation liquid is incorporated into the first separation liquid for recycling; then calcining the precipitated solid, the calcination temperature is 350° C., the time is 5 hours, and a calcination residue and tail gas are obtained, wherein the calcination residue is calcium oxide, which is returned as a neutralizing reagent for the hydrochloric acid solution;

[0085] (4) The tail gas generated by the calcination in step (3) is used for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1), wherein the tail gas includes carbon dioxide and carbon monoxide, and the temperature of the calcination, decomposition and reduction is 700° C. and the time is 7 hours; during the calcination and decomposition, basic copper carbonate is decomposed into copper oxide, and iron hydroxide is decomposed into iron oxide. During the calcination and reduction, carbon monoxide is used as a reducing agent, and copper oxide is reduced to copper and iron oxide is reduced to iron to obtain a copper-iron mixed solid. The tail gas generated during the calcination, decomposition and reduction process is absorbed by the sodium hydroxide solution in step (2), and then returned to step (1) for use as an alkali solution; the copper-iron mixed solid is then subjected to magnetic separation treatment, and the frequency of the magnetic separation treatment is 20 Hz, the gap is 15 mm, and the magnetic declination is 5 degrees, so as to separate metallic copper and metallic iron.

[0086] In this embodiment, after the copper- and iron-containing etching waste liquid is recovered, the purity of the obtained copper element is 98.5%, and the yield is 99.1%. The purity of the iron element is 99.2%, and the yield is 98.9%.

[0087] Embodiment 2:

[0088] This embodiment provides a method for recycling copper and iron-containing etching waste liquid, the method comprising the following steps:

[0089] (1) slowly and uniformly adding copper-containing and iron-containing etching waste liquid to the heated alkali solution, wherein the copper-containing and iron-containing etching waste liquid is an etching waste liquid obtained by etching a ferric chloride solution, and contains ferric chloride, cupric chloride and hydrochloric acid, wherein the copper content is 50 g / L, the iron content is 20 g / L, the chloride ion content is 120 g / L, and the free acid content is 1 mol / L. The alkali solution is a sodium carbonate solution, and the concentration of the alkali solution is 1.2 mol / L. The rate at which the copper-containing and iron-containing etching waste liquid is added is 85 mL / s, and the alkali solution is added in advance. Heat to 70°C, stir and maintain the temperature during the reaction, react until the pH value drops to 6.5, and then age, maintain the reaction temperature during the ageing, the ageing time is 0.8h, and then cool to room temperature and filter and separate to obtain a copper-iron mixed solid and a first separated liquid; the copper-iron mixed solid is a mixed solid of basic copper carbonate and ferric hydroxide, add water to pulp and wash, the solid-liquid mass ratio of the pulping and washing is 1:1.2, the time is 1.5h, and then after filtration and separation, the washing water is incorporated into the first separated liquid;

[0090] (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment, wherein the bipolar membrane and anionic and cationic membranes are used in combination, wherein the bipolar membrane is an anionic and cationic composite membrane, and direct current is applied during the bipolar membrane treatment, wherein the voltage is 8 V and the current is 2.5 A, and the temperature of the bipolar membrane treatment is 35° C., to obtain a sodium hydroxide solution and a hydrochloric acid solution;

[0091] (3) neutralizing the hydrochloric acid solution obtained in step (2) and precipitating the solution, wherein the reagent used for the neutralization is calcium oxide, the neutralization endpoint pH is 5.6, the reagent used for the precipitation is sodium oxalate, the precipitation time is 3 hours, and after separation by suction filtration, a solid precipitate and a second separation liquid are obtained, wherein the solid precipitate is calcium oxalate solid, the solid precipitate is pulped and washed with water, the solid-liquid mass ratio of the pulping and washing is 1:1.8, and the time is 2.5 hours, and after separation by filtration, the washing water is incorporated into the second separation liquid, and the second separation liquid is incorporated into the first separation liquid for recycling; and then calcining the precipitated solid, wherein the calcination temperature is 400° C. and the time is 4 hours, to obtain a calcination residue and tail gas, wherein the calcination residue is calcium oxide, which is returned as a neutralizing reagent for the hydrochloric acid solution;

[0092] (4) The tail gas generated by the calcination in step (3) is used for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1), wherein the tail gas includes carbon dioxide and carbon monoxide, and the temperature of the calcination, decomposition and reduction is 750° C. and the time is 6 hours; during the calcination and decomposition, basic copper carbonate is decomposed into copper oxide, and iron hydroxide is decomposed into iron oxide. During the calcination and reduction, carbon monoxide is used as a reducing agent, and copper oxide is reduced to copper and iron oxide is reduced to iron to obtain a copper-iron mixed solid. The tail gas generated during the calcination, decomposition and reduction process is absorbed by the sodium hydroxide solution in step (2), and then returned to step (1) for use as an alkali solution; the copper-iron mixed solid is then subjected to magnetic separation treatment, and the frequency of the magnetic separation treatment is 40 Hz, the gap is 20 mm, and the magnetic declination is 12 degrees, so as to separate metallic copper and metallic iron.

[0093] In this embodiment, after the copper- and iron-containing etching waste liquid is recovered, the purity of the obtained copper element is 99.3%, and the yield is 99.4%. The purity of the iron element is 98.4%, and the yield is 98.7%.

[0094] Embodiment 3:

[0095] This embodiment provides a method for recycling copper and iron-containing etching waste liquid, the method comprising the following steps:

[0096] (1) slowly and uniformly adding copper-containing and iron-containing etching waste liquid to the heated alkali solution, wherein the copper-containing and iron-containing etching waste liquid is an etching waste liquid obtained by etching a ferric chloride solution, and contains ferric chloride, cupric chloride and hydrochloric acid, wherein the copper content is 60 g / L, the iron content is 30 g / L, the chloride ion content is 190 g / L, and the free acid content is 2 mol / L. The alkali solution is a sodium carbonate solution, and the concentration of the alkali solution is 1.5 mol / L. The rate at which the copper-containing and iron-containing etching waste liquid is added is 95 mL / s. The alkali solution The mixture is heated to 75° C. in advance, stirred and maintained at a temperature during the reaction, and the reaction is terminated after the pH value drops to 7, and then aged, wherein the reaction temperature is maintained during the aging, and the aging time is 1 hour. The mixture is then cooled to room temperature and filtered to obtain a copper-iron mixed solid and a first separated liquid. The copper-iron mixed solid is a mixed solid of basic copper carbonate and ferric hydroxide, and water is added for pulping and washing, wherein the solid-liquid mass ratio of the pulping and washing is 1:1.5, and the time is 2 hours. After separation by filtration, the washing water is incorporated into the first separated liquid.

[0097] (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment, wherein the bipolar membrane and anion and cation membranes are used in combination, wherein the bipolar membrane is an anion and cation composite membrane, and direct current is applied during the bipolar membrane treatment, wherein the voltage is 12 V and the current is 3.5 A, and the temperature of the bipolar membrane treatment is 20° C., to obtain a sodium hydroxide solution and a hydrochloric acid solution;

[0098] (3) neutralizing the hydrochloric acid solution obtained in step (2) and then precipitating, wherein the reagent used for the neutralization is calcium oxide, the neutralization endpoint pH is 6, the reagent used for the precipitation is sodium oxalate, the precipitation time is 4 hours, and after separation by suction filtration, a solid precipitate and a second separation liquid are obtained, wherein the solid precipitate is calcium oxalate solid, the solid precipitate is pulped and washed with water, the solid-liquid mass ratio of the pulping and washing is 1:2, and the time is 3 hours, and after separation by filtration, the washing water is incorporated into the second separation liquid, and the second separation liquid is incorporated into the first separation liquid for recycling; and then calcining the precipitated solid, the calcination temperature is 450° C., the time is 3 hours, and a calcination residue and tail gas are obtained, wherein the calcination residue is calcium oxide, which is returned as a neutralizing reagent for the hydrochloric acid solution;

[0099] (4) The tail gas generated by the calcination in step (3) is used for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1), wherein the tail gas includes carbon dioxide and carbon monoxide, and the temperature of the calcination, decomposition and reduction is 800° C. and the time is 5 hours; during the calcination and decomposition, basic copper carbonate is decomposed into copper oxide, and iron hydroxide is decomposed into iron oxide. During the calcination and reduction, carbon monoxide is used as a reducing agent, and copper oxide is reduced to copper and iron oxide is reduced to iron to obtain a copper-iron mixed solid. The tail gas generated during the calcination, decomposition and reduction process is absorbed by the sodium hydroxide solution in step (2), and then returned to step (1) for use as an alkali solution; the copper-iron mixed solid is then subjected to magnetic separation treatment, and the frequency of the magnetic separation treatment is 50 Hz, the gap is 25 mm, and the magnetic declination is 18 degrees, so as to separate metallic copper and metallic iron.

[0100] In this embodiment, after the copper- and iron-containing etching waste liquid is recovered, the purity of the obtained copper element is 99.4%, and the yield is 98.9%. The purity of the iron element is 97.7%, and the yield is 98.4%.

[0101] Embodiment 4:

[0102] This embodiment provides a method for recycling copper and iron-containing etching waste liquid, the method comprising the following steps:

[0103] (1) slowly and uniformly adding copper- and iron-containing etching waste liquid to the heated alkali solution, wherein the copper- and iron-containing etching waste liquid is an etching waste liquid obtained by etching a ferric chloride solution, and contains ferric chloride, cupric chloride and hydrochloric acid, wherein the copper content is 52 g / L, the iron content is 28 g / L, the chloride ion content is 170 g / L, and the free acid content is 1.6 mol / L. The alkali solution is a potassium carbonate solution, and the concentration of the alkali solution is 1.7 mol / L. The rate of adding the copper- and iron-containing etching waste liquid is 80 mL / s, and the alkali solution is heated in advance. The mixture was heated to 68° C., stirred and maintained at the temperature during the reaction, and the reaction was terminated after the pH value dropped to 6.2, and then aged, wherein the reaction temperature was maintained during the aging, and the aging time was 0.6 h. The mixture was then cooled to room temperature and filtered to obtain a copper-iron mixed solid and a first separated liquid. The copper-iron mixed solid was a mixed solid of basic copper carbonate and ferric hydroxide, and water was added for pulping and washing, and the solid-liquid mass ratio of the pulping and washing was 1:1.1, and the time was 1.2 h. After separation by filtration, the washing water was incorporated into the first separated liquid.

[0104] (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment, wherein the bipolar membrane and anion and cation membranes are used in combination, wherein the bipolar membrane is an anion and cation composite membrane, and direct current is applied during the bipolar membrane treatment, the voltage is 11 V, the current is 3.2 A, and the temperature of the bipolar membrane treatment is 30° C., to obtain a potassium hydroxide solution and a hydrochloric acid solution;

[0105] (3) neutralizing the hydrochloric acid solution obtained in step (2) and then precipitating, wherein the reagent used for the neutralization is calcium hydroxide, the neutralization endpoint pH is 5.4, the reagent used for the precipitation is potassium oxalate, the precipitation time is 2.5 hours, and after separation by suction filtration, a solid precipitate and a second separation liquid are obtained, wherein the solid precipitate is calcium oxalate solid, the solid precipitate is pulped and washed with water, the solid-liquid mass ratio of the pulping and washing is 1:1.6, and the time is 2.25 hours, and after separation by filtration, the washing water is incorporated into the second separation liquid, and the second separation liquid is incorporated into the first separation liquid for recycling; and then calcining the precipitated solid, the calcination temperature is 380° C., the time is 3.5 hours, and a calcination residue and tail gas are obtained, wherein the calcination residue is calcium oxide, which is returned as a neutralizing reagent for the hydrochloric acid solution;

[0106] (4) The tail gas generated by the calcination in step (3) is used for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1), wherein the tail gas includes carbon dioxide and carbon monoxide, and the temperature of the calcination, decomposition and reduction is 720° C. and the time is 5.5 hours; during the calcination and decomposition, basic copper carbonate is decomposed into copper oxide, and iron hydroxide is decomposed into iron oxide. During the calcination and reduction, carbon monoxide is used as a reducing agent, and copper oxide is reduced to copper and iron oxide is reduced to iron to obtain a copper-iron mixed solid. The tail gas generated during the calcination, decomposition and reduction process is absorbed by the potassium hydroxide solution in step (2), and then returned to step (1) for use as an alkali solution; the copper-iron mixed solid is then subjected to magnetic separation treatment, and the frequency of the magnetic separation treatment is 30 Hz, the gap is 18 mm, and the magnetic declination is 10 degrees, so as to separate metallic copper and metallic iron.

[0107] In this embodiment, after the copper- and iron-containing etching waste liquid is recovered, the purity of the obtained copper element is 99.0%, and the yield is 98.8%. The purity of the iron element is 98.7%, and the yield is 98.5%.

[0108] Embodiment 5:

[0109] This embodiment provides a method for recycling copper and iron-containing etching waste liquid, the method comprising the following steps:

[0110] (1) slowly and uniformly adding copper-containing and iron-containing etching waste liquid to the heated alkali solution, wherein the copper-containing and iron-containing etching waste liquid is an etching waste liquid obtained by etching a ferric chloride solution, and contains ferric chloride, cupric chloride and hydrochloric acid, wherein the copper content is 58 g / L, the iron content is 24 g / L, the chloride ion content is 150 g / L, and the free acid content is 1.2 mol / L. The alkali solution is a sodium bicarbonate solution, and the concentration of the alkali solution is 1.4 mol / L. The rate at which the copper-containing and iron-containing etching waste liquid is added is 100 mL / s, and the alkali solution is extracted with water. The mixture is heated to 72°C before reaction, stirred and maintained at a temperature during the reaction, and the reaction is terminated after the pH value drops to 6.6, and then aged, the reaction temperature is maintained during the aging, and the aging time is 0.9h. After cooling to room temperature, the mixture is filtered and separated to obtain a copper-iron mixed solid and a first separated liquid; the copper-iron mixed solid is a mixed solid of basic copper carbonate and ferric hydroxide, and water is added for pulping and washing, the solid-liquid mass ratio of the pulping and washing is 1:1.4, the time is 1.75h, and after separation by filtration, the washing water is incorporated into the first separated liquid;

[0111] (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment, wherein the bipolar membrane and anionic and cationic membranes are used in combination, wherein the bipolar membrane is an anionic and cationic composite membrane, and direct current is applied during the bipolar membrane treatment, wherein the voltage is 9 V and the current is 2.8 A, and the temperature of the bipolar membrane treatment is 27° C., to obtain a sodium hydroxide solution and a hydrochloric acid solution;

[0112] (3) neutralizing the hydrochloric acid solution obtained in step (2) and then precipitating, wherein the reagent used for the neutralization is calcium hydroxide, the neutralization endpoint pH is 5.8, the reagent used for the precipitation is sodium oxalate, the precipitation time is 3.5 hours, and after separation by suction filtration, a solid precipitate and a second separation liquid are obtained, wherein the solid precipitate is calcium oxalate solid, the solid precipitate is pulped and washed with water, the solid-liquid mass ratio of the pulping and washing is 1:1.8, and the time is 2.75 hours, and after separation by filtration, the washing water is incorporated into the second separation liquid, and the second separation liquid is incorporated into the first separation liquid for recycling; and then calcining the precipitated solid, the calcination temperature is 420° C., the time is 4.5 hours, and a calcination residue and tail gas are obtained, wherein the calcination residue is calcium oxide, which is returned as a neutralizing reagent for the hydrochloric acid solution;

[0113] (4) The tail gas generated by the calcination in step (3) is used for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1), wherein the tail gas includes carbon dioxide and carbon monoxide, and the temperature of the calcination, decomposition and reduction is 780° C. and the time is 6.5 hours; during the calcination and decomposition, basic copper carbonate is decomposed into copper oxide, and iron hydroxide is decomposed into iron oxide. During the calcination and reduction, carbon monoxide is used as a reducing agent, and copper oxide is reduced to copper and iron oxide is reduced to iron to obtain a copper-iron mixed solid. The tail gas generated during the calcination, decomposition and reduction process is absorbed by the sodium hydroxide solution in step (2), and then returned to step (1) for use as an alkali solution; the copper-iron mixed solid is then subjected to magnetic separation treatment, and the frequency of the magnetic separation treatment is 45 Hz, the gap is 22 mm, and the magnetic declination is 15 degrees, so as to separate metallic copper and metallic iron.

[0114] In this embodiment, after the copper- and iron-containing etching waste liquid is recovered, the purity of the obtained copper element is 99.2%, and the yield is 98.9%. The purity of the iron element is 99.1%, and the yield is 98.8%.

[0115] Comparative Example 1:

[0116] This comparative example provides a method for recycling copper- and iron-containing etching waste liquid. The method refers to the method in Example 1, with the only difference being that the alkali solution used in step (1) is a sodium hydroxide solution, and the endpoint pH value of the reaction is controlled to be above 10.

[0117] In this comparative example, when sodium hydroxide solution is used as the alkali solution, copper hydroxide precipitate is generated with copper ions. In order to precipitate the copper ions as completely as possible, the endpoint pH value of the reaction is relatively high, which needs to be above 10. Therefore, the amount of alkali solution required to treat the same etching waste liquid is greatly increased, and the precipitated solution needs to be adjusted again before subsequent bipolar membrane treatment can be carried out, thereby greatly increasing the treatment cost of the etching waste liquid.

[0118] From the above embodiments and comparative examples, it can be seen that the method of the present invention, according to the composition characteristics of the copper-containing and iron-containing etching waste liquid, first adopts a neutralization and alkalization method to solidify the free copper and iron ions to form copper-containing and iron-containing precipitates, and the remaining solution is treated by a bipolar membrane to form an acid and alkaline solution, and then the acid solution is neutralized, precipitated, calcined, etc., and the tail gas generated is used for calcination, decomposition and reduction of the copper-containing and iron-containing precipitates, thereby obtaining copper and iron metal elements, and then the metallic copper and iron are recovered by magnetic separation, respectively, to achieve full recovery and utilization of each component in the etching waste liquid, and reduce the difficulty and danger of etching waste liquid treatment; the method is simple to operate, the intermediate product can be recycled, the processing cost is reduced, and no secondary pollution is generated.

[0119] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the method of the present invention, addition of auxiliary steps, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for recycling copper and iron-containing etching waste liquid, characterized in that: The method comprises the following steps: (1) adding the copper- and iron-containing etching waste liquid to the heated alkali solution, maintaining the temperature, aging after the reaction is completed, and then separating the solid and the liquid after cooling to obtain a copper- and iron-containing mixed solid and a first separated liquid; (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment to obtain a caustic soda solution and a hydrochloric acid solution; (3) neutralizing the hydrochloric acid solution obtained in step (2) and precipitating the solution, and calcining the precipitated solid after solid-liquid separation to obtain a calcination residue and tail gas; (4) The tail gas generated by the calcination in step (3) is used for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1) to obtain a copper-iron mixed solid, which is then subjected to magnetic separation to separate metallic copper and metallic iron.

2. The method according to claim 1, characterized in that: The copper- and iron-containing etching waste liquid in step (1) is an etching waste liquid obtained by etching a ferric chloride solution, wherein the etching waste liquid contains ferric chloride, cupric chloride and hydrochloric acid; Preferably, the copper content in the copper-iron etching waste liquid in step (1) is 50-60 g / L, the iron content is 20-30 g / L, the chloride ion content is 100-200 g / L, and the free acid content is 1-2 mol / L; Preferably, the alkali solution in step (1) comprises an alkali metal carbonate solution and / or an alkali metal bicarbonate solution, preferably comprising any one of sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate, or a combination of at least two thereof; Preferably, the concentration of the alkali solution in step (1) is 1 to 2 mol / L.

3. The method according to claim 1 or 2, characterized in that: The copper and iron etching waste liquid in step (1) is slowly and uniformly added into the alkaline solution; Preferably, the copper- and iron-containing etching waste liquid is added at a rate of 70 to 100 mL / s; Preferably, the alkali solution in step (1) is heated to 65-75° C. in advance; Preferably, the temperature of 65-75° C. is maintained during the reaction in step (1), and the reaction is terminated when the pH value drops to 6-7.

4. The method according to any one of claims 1 to 3, characterized in that: During the aging in step (1), the reaction temperature is maintained, and the aging time is 0.5 to 1 hour; Preferably, the step (1) is cooling to room temperature; Preferably, the solid-liquid separation in step (1) comprises filtration separation, preferably suction filtration separation; Preferably, the copper-iron mixed solid in step (1) is a mixed solid of basic copper carbonate and ferric hydroxide; Preferably, the copper-iron mixed solid in step (1) is slurried and washed with water, and then after solid-liquid separation, the washing water is incorporated into the first separated liquid; Preferably, the solid-liquid mass ratio of the beating washing is 1:(1-1.5); Preferably, the beating and washing time is 1 to 2 hours.

5. The method according to any one of claims 1 to 4, characterized in that: In step (2), the bipolar membrane treatment uses a bipolar membrane in combination with an anionic and cationic membrane, wherein the bipolar membrane is an anionic and cationic composite membrane; Preferably, direct current is applied during the bipolar membrane treatment in step (2); Preferably, the voltage of the bipolar membrane treatment in step (2) is 8 to 12 V; Preferably, the current of the bipolar membrane treatment in step (2) is 2.5 to 3.5 A; Preferably, the temperature of the bipolar membrane treatment in step (2) is 20-35° C. Preferably, the caustic soda solution in step (2) comprises sodium hydroxide solution or potassium hydroxide solution.

6. The method according to any one of claims 1 to 5, characterized in that: The reagent used for neutralization in step (3) includes calcium oxide and / or calcium hydroxide; Preferably, the neutralization endpoint pH in step (3) is 5 to 6; Preferably, the reagent used for the precipitation in step (3) comprises oxalate, preferably sodium oxalate or potassium oxalate; Preferably, the precipitation time in step (3) is 2 to 4 hours; Preferably, the solid-liquid separation in step (3) comprises filtration separation, preferably suction filtration separation; Preferably, the solid-liquid separation in step (3) obtains a solid precipitate and a second separated liquid, wherein the solid precipitate comprises calcium oxalate solid; Preferably, the solid precipitate in step (3) is slurried and washed with water, and after solid-liquid separation, the washing water is incorporated into the second separation liquid, and the second separation liquid is incorporated into the first separation liquid for recycling; Preferably, the solid-liquid mass ratio of the beating washing is 1:(1.5-2); Preferably, the beating and washing time is 2 to 3 hours.

7. The method according to any one of claims 1 to 6, characterized in that: The calcination temperature in step (3) is 350-450° C. Preferably, the calcination time in step (3) is 3 to 5 hours; Preferably, the calcined residue in step (3) comprises calcium oxide, and the calcium oxide is returned as a neutralizing agent for the hydrochloric acid solution.

8. The method according to any one of claims 1 to 7, characterized in that: The tail gas in step (4) includes carbon dioxide and carbon monoxide; Preferably, the temperature of the calcination, decomposition and reduction in step (4) is 700-800° C. and the time is 5-7 h; Preferably, during the calcination and decomposition in step (4), basic copper carbonate decomposes into copper oxide, and iron hydroxide decomposes into iron oxide; Preferably, during the calcination reduction in step (4), carbon monoxide is used as a reducing agent, copper oxide is reduced to copper, and iron oxide is reduced to iron; Preferably, the tail gas generated during the calcination, decomposition and reduction process in step (4) is absorbed by the caustic soda solution in step (2) and then returned to step (1) for use as alkaline solution.

9. The method according to any one of claims 1 to 8, characterized in that: The frequency of the magnetic separation treatment in step (4) is 20 to 50 Hz; Preferably, the gap of the magnetic separation treatment in step (4) is 15 to 25 mm; Preferably, the magnetic declination angle of the magnetic separation treatment in step (4) is 5 to 20 degrees.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) slowly and uniformly adding copper- and iron-containing etching waste liquid to the heated alkali solution, wherein the copper- and iron-containing etching waste liquid is an etching waste liquid obtained by etching a ferric chloride solution, and contains ferric chloride, cupric chloride and hydrochloric acid, wherein the copper content is 50-60 g / L, the iron content is 20-30 g / L, the chloride ion content is 100-200 g / L, and the free acid content is 1-2 mol / L. The alkali solution includes an alkali metal carbonate solution and / or an alkali metal bicarbonate solution, and the concentration of the alkali solution is 1-2 mol / L. The rate of adding the copper- and iron-containing etching waste liquid is 70-100 mL / s , the alkali solution is heated to 65-75°C in advance, the temperature is maintained during the reaction, the reaction is terminated after the pH value drops to 6-7, and then aging is performed, the reaction temperature is maintained during the aging, the aging time is 0.5-1h, and then the solid-liquid separation is performed after cooling to room temperature, the solid-liquid separation includes filtration separation, and a copper-iron mixed solid and a first separated liquid are obtained; the copper-iron mixed solid is a mixed solid of basic copper carbonate and ferric hydroxide, water is added for pulping and washing, the solid-liquid mass ratio of the pulping and washing is 1:(1-1.5), the time is 1-2h, and after solid-liquid separation, the washing water is incorporated into the first separated liquid; (2) subjecting the first separated liquid obtained in step (1) to bipolar membrane treatment, wherein the bipolar membrane and anion and cation membranes are used in combination, wherein the bipolar membrane is an anion and cation composite membrane, and direct current is applied during the bipolar membrane treatment, wherein the voltage is 8 to 12 V and the current is 2.5 to 3.5 A, and the temperature of the bipolar membrane treatment is 20 to 35° C., to obtain a caustic solution and a hydrochloric acid solution, wherein the caustic solution comprises a sodium hydroxide solution or a potassium hydroxide solution; (3) neutralizing the hydrochloric acid solution obtained in step (2) and then precipitating, wherein the reagent used for the neutralization comprises calcium oxide and / or calcium hydroxide, the neutralization end point pH is 5-6, the reagent used for the precipitation comprises oxalate, the precipitation time is 2-4 hours, and after solid-liquid separation, a solid precipitate and a second separated liquid are obtained, wherein the solid precipitate comprises calcium oxalate solid, the solid precipitate is pulped and washed with water, the solid-liquid mass ratio of the pulping and washing is 1:(1.5-2), the time is 2-3 hours, and after solid-liquid separation, the washing water is incorporated into the second separated liquid, and the second separated liquid is incorporated into the first separated liquid for recycling; and then the precipitated solid is calcined, the calcination temperature is 350-450° C., the time is 3-5 hours, and a calcination residue and tail gas are obtained, wherein the calcination residue comprises calcium oxide, and the calcium oxide is returned as a neutralizing reagent for the hydrochloric acid solution; (4) using the tail gas generated by the calcination in step (3) for the calcination, decomposition and reduction of the copper-iron mixed solid in step (1), wherein the tail gas includes carbon dioxide and carbon monoxide, and the temperature of the calcination, decomposition and reduction is 700-800° C. and the time is 5-7 hours; during the calcination and decomposition, basic copper carbonate is decomposed into copper oxide, and iron hydroxide is decomposed into iron oxide; during the calcination and reduction, carbon monoxide is used as a reducing agent, and copper oxide is reduced to copper and iron oxide is reduced to iron, thereby obtaining a copper-iron mixed solid; the tail gas generated during the calcination, decomposition and reduction process is absorbed by the caustic soda solution in step (2), and then returned to step (1) for use as alkaline solution; the copper-iron mixed solid is then subjected to magnetic separation treatment, and the frequency of the magnetic separation treatment is 20-50 Hz, the gap is 15-25 mm, and the magnetic declination is 5-20 degrees, so as to separate metallic copper and metallic iron.

Images