System and method for producing active copper oxide ammonia water and salt using alkaline etching waste liquid

Abstract

The invention discloses a system and method for producing active copper oxide ammonia water and salt by using alkaline etching waste liquid, comprising an alkaline etching waste liquid storage tank, an active copper oxide recovery device, a salt recovery device, an ammonia water recovery device and a vacuum device; the active copper oxide recovery device comprises a copper oxide reactor, a first centrifugal filter and a Cu + The chelating recovery device, the copper oxide reactor is connected to the alkaline material input device and the alkaline etching waste liquid storage tank, and its discharge port is connected to the first centrifugal filter device; the gas outlet at the top of the copper oxide reactor is connected to the ammonia water recovery device, and the ammonia water recovery device is also connected to the vacuum device. The present invention obtains high-value active copper oxide products and basic chemical products ammonia water and salt, realizes the thorough and comprehensive recycling of alkaline etching waste liquid, effectively solves the problem of secondary pollution, and has high economic benefits.

Description

Technical Field

[0001] The invention relates to the field of chemical product production and chemical engineering, and in particular to a system and method for producing active copper oxide ammonia water and salt by utilizing alkaline etching waste liquid. Background Art

[0002] With the global resource shortage, especially the scarcity of copper resources in my country, a large amount of copper resources are imported from abroad. It is necessary to make full use of the copper resources in waste to develop my country's circular economy. At present, the scarcity of active copper oxide in my country has increased with the annual increase in the output of PCB (printed circuit board) products. A large amount of active copper oxide is imported from Japan and South Korea, and the import volume accounts for 70% of the amount used by domestic PCB companies. Alkaline etching waste liquid contains a certain amount of Cu + Its effective recovery is of great significance to alleviating the scarcity of copper resources in my country.

[0003] However, the current alkaline etching waste liquid disposal and comprehensive utilization technology is backward and the facilities are simple. For example, the disclosed technologies of Chinese patents CN200610096213.4, CN 105002500A, CN105174536A, CN211688362, etc., a large amount of alkaline etching waste liquid is utilized as copper hydroxide mud or low-value basic copper chloride in the disposal and utilization process of the current technology. On the one hand, copper resources are recycled as low-value products and are not effectively utilized, which causes a waste of copper resources to a certain extent and may also cause secondary pollution of heavy metal copper ions; on the other hand, the copper hydroxide mud or basic copper chloride used as low-value is not effectively separated and proposed, and it also contains components that can cause secondary pollution, such as the copper hydroxide copper mud produces hydrogen chloride and ammonia waste gas during the smelting and reuse process, produces high-salt wastewater, etc., and pollutes the atmospheric environment. Summary of the invention

[0004] The invention solves the above-mentioned problems existing in the recycling and treatment of alkaline etching waste liquid in the prior art by providing a system and a method for producing active copper oxide ammonia water and salt by utilizing alkaline etching waste liquid.

[0005] In order to solve the above technical problems, the present invention provides a system for producing active copper oxide ammonia water and salt by using alkaline etching waste liquid, comprising: an alkaline etching waste liquid storage tank, an active copper oxide recovery device, a salt recovery device, an ammonia water recovery device and a vacuum device; wherein the active copper oxide recovery device comprises a copper oxide reactor, a first centrifugal filter and a Cu + The chelating recovery device has a feed port connected to the alkaline material input device and the alkaline etching waste liquid storage tank, and its discharge port is connected to the first centrifugal filter device, and the filtrate outlet of the first centrifugal filter device is connected to the Cu + The chelating recovery device is connected, and the Cu+ The chelate waste liquid outlet of the chelate recovery device is connected to the salt recovery device; the gas outlet at the top of the copper oxide reactor is connected to the ammonia recovery device, and the ammonia recovery device is also connected to the vacuum device.

[0006] In a preferred embodiment of the present invention, a circulating liquid inlet tangent port is provided on one side of the upper portion of the copper oxide reactor, and a circulating liquid outlet tangent port is provided on one side of the lower portion thereof, and the circulating liquid inlet tangent port and the circulating liquid outlet tangent port are connected via a circulating pipeline with a first forced circulation pump.

[0007] In a preferred embodiment of the present invention, a spiral separator is also installed on the circulation pipeline, the slurry outlet of the spiral separator is connected to the circulation liquid inlet tangent port, and its clear liquid outlet extends into the copper oxide reactor through a pipeline and is connected to a spray mist maker.

[0008] In a preferred embodiment of the present invention, the salt recovery device comprises an evaporative crystallizer and a second centrifugal filter, the feed port of the evaporative crystallizer is connected to the Cu + The chelate waste liquid outlet of the chelate recovery device is connected, and its discharge port is connected with the second centrifugal filter.

[0009] In a preferred embodiment of the present invention, the ammonia water recovery device includes a condensate collector and an ammonia water recovery tank, wherein the tube side inlet of the condensate collector is connected to the gas outlet at the top of the copper oxide reactor and the evaporation crystallizer, the tube side outlet of the condensate collector is connected to the ammonia water collection tank, and the ammonia water collection tank is connected to the vacuum pumping device.

[0010] In a preferred embodiment of the present invention, the water outlet of the ammonia water collecting tank is connected to the top of the condensation collector through a pipeline with a circulation pump, and an ammonia water discharge valve is installed on the pipeline.

[0011] In a preferred embodiment of the present invention, the system also includes a heat exchanger, and the tube-side inlet and tube-side outlet of the heat exchanger are connected to the evaporative condenser through pipelines respectively, and a second forced circulation pump is also installed on the pipeline connecting the tube-side outlet of the heat exchanger and the evaporative condenser.

[0012] In a preferred embodiment of the present invention, the gas outlet at the top of the copper oxide reactor and the gas outlet at the top of the evaporation crystallizer are both connected to the shell inlet of the heat exchanger through a pipeline, and the shell outlet of the heat exchanger is also opened with a steam outlet and a condensate outlet, the steam outlet is connected to the pipe side of the condensate collector, and the condensate outlet is connected to the ammonia water collection tank.

[0013] In order to solve the above technical problems, the present invention also provides a method for systematically producing active copper oxide ammonia water and salt, comprising the following steps:

[0014] (1) Vacuuming: Turn on the vacuuming device to put the entire system in a negative pressure state;

[0015] (2) Recovering active copper oxide: filtering the alkaline etching waste liquid in the alkaline etching waste liquid storage tank and transporting it to the copper oxide reactor, and simultaneously adding an excess of alkaline material to recover the Cu in the alkaline etching waste liquid. + Cu(OH) is generated in the copper oxide reactor 2 The CuO crystals are converted into CuO crystals at 50-100°C under oxidation conditions. The slurry containing the CuO crystals enters the first centrifugal filter from the outlet of the copper oxide reactor. The CuO wet product after centrifugal filtration is dried and crushed to obtain active CuO. The mother liquor after centrifugal separation is transported to the CuO reactor. + Chelating recovery of Cu in the chelating recovery device + , the chelated waste liquid is transported to the evaporation crystallizer through a pipeline;

[0016] (3) recovering salt: after the chelated waste liquid entering the evaporation crystallizer is evaporated and water is removed, the resulting salt is discharged from the discharge port of the evaporation crystallizer and enters the second centrifugal filter. The salt after centrifugal filtration is then dried to obtain finished salt, and the filtrate is returned to the evaporation crystallizer;

[0017] (4) Recovering ammonia water: The ammonia water vapor generated in the copper oxide reactor in step (2) and the ammonia water vapor generated in the evaporation crystallizer are transported to the condensation recovery tube of the ammonia water recovery device through a pipeline, and are recovered as ammonia water after condensation.

[0018] In a preferred embodiment of the present invention, the step (4) is: the ammonia water vapor generated in the copper oxide reactor in the step (2) and the ammonia water vapor generated in the evaporation crystallizer are first introduced into the shell side inlet of the heat exchanger, and the ammonia water vapor and ammonia condensed water after heat exchange enter the condensate collector and the ammonia water collection tank respectively through the steam outlet and the condensate outlet on the shell side of the heat exchanger.

[0019] The beneficial effects of the present invention are as follows: the system and method for producing active copper oxide ammonia water and salt by using alkaline etching waste liquid, through the combined design of active copper oxide recovery device, salt recovery device and ammonia water recovery device and the use of alkaline materials (sodium hydroxide or potassium hydroxide), copper oxide is generated while salt and ammonia water are recovered, thereby achieving thorough and comprehensive recycling of alkaline etching waste liquid, effectively solving the problem of secondary pollution, and achieving a utilization rate of hazardous waste resources of 10%.

[0020] More than 99.9%, achieving zero pollution emissions, and obtaining high-value active copper oxide products and basic chemical products ammonia water and salt, with high economic benefits and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a system for producing active copper oxide ammonia water and salt by using alkaline etching waste liquid in the present invention;

[0022] Figure 2 It is a schematic diagram of the process of producing active copper oxide ammonia water and salt by using alkaline etching waste liquid in the present invention;

[0023] The markings of the components in the accompanying drawings are as follows:

[0024] 100. Alkaline etching waste liquid storage tank;

[0025] 200. Vacuum extraction device;

[0026] 310. Copper oxide reactor, 311. Circulation liquid inlet tangent port, 312. Circulation liquid outlet tangent port, 313. Circulation pipeline, 314. First forced circulation pump, 315. Spiral separator, 316. Spray mist generator, 320. First centrifugal filter, 330. Cu + Chelating recovery device, 340. Alkaline material input device, 350. First conveyor, 360. First dryer, 370. Crusher;

[0027] 410. evaporation crystallizer, 420. second centrifugal filter, 430. heat exchanger, 440. second forced circulation pump, 450. second conveyor, 460. second dryer, 431. shell side inlet, 432. steam outlet, 433. condensate outlet;

[0028] 510. Condensate collector, 520. Ammonia recovery tank, 530. Refrigerator, 521. Circulation pump, 522. Ammonia discharge valve, 531. Refrigerant delivery pump. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0030] See also Figure 1 and Figure 2 , the embodiment of the present invention includes:

[0031] The present invention discloses a method for producing active copper oxide, ammonia water and salt by using alkaline etching waste liquid, wherein the salt may be potassium chloride or sodium chloride. Taking sodium chloride as an example, active copper oxide is prepared by adding an excess of sodium hydroxide to the alkaline etching waste liquid, and by-products ammonia water and sodium chloride are prepared. The system used includes: an alkaline etching waste liquid storage tank 100, an active copper oxide recovery device, a salt recovery device, an ammonia water recovery device and a vacuum device 200.

[0032] The active copper oxide recovery device includes a copper oxide reactor 310, a first centrifugal filter 320 and a Cu + Chelating recovery device 330; wherein the copper oxide reactor 310 is a forced circulation reactor, a circulation liquid inlet tangent port 311 is provided on one side of the upper part thereof, a circulation liquid outlet tangent port 312 is provided on one side of the lower part thereof, the circulation liquid inlet tangent port 311 and the circulation liquid outlet tangent port 312 are connected through a circulation pipeline 313, and a first forced circulation pump 314 is installed on the circulation pipeline 313. A spiral separator 315 is also installed on the circulation pipeline 313 near one end of the circulation liquid inlet tangent port 311, the slurry outlet of the spiral separator 315 is connected to the circulation liquid inlet tangent port 311, the clear liquid outlet of the spiral separator 315 extends into the copper oxide reactor 310 through a pipeline, and is connected to a spray mist maker 316. The spiral separator 315 is designed to separate the materials circulating in the copper oxide reactor 310 into slurry and clear liquid (i.e., sodium chloride clear liquid). The slurry enters the copper oxide reactor 310 through the circulating liquid inlet tangent port 311 to drive the reaction liquid to rotate, and the sodium chloride clear liquid is then sprayed out from the spray mist generator 316, which is beneficial to the NH 3 After being fully volatilized and separated, it is discharged from the outlet at the top of the copper oxide reactor 310.

[0033] The feed port of the copper oxide reactor 310 is connected to the alkaline material input device 340 and the alkaline etching waste liquid storage tank 100, wherein the alkaline material input device 340 is a sodium hydroxide feeder in this embodiment; the outlet of the alkaline etching waste liquid storage tank 100 is first connected to the filter 120 through a pipeline equipped with an alkali solution delivery pump 110, and the filtrate outlet of the filter 120 is connected to the feed port of the copper oxide reactor 310 through a pipeline.

[0034] The discharge port of the copper oxide reactor 310 is provided with a cutting pump, and the discharge port is communicated with the first centrifugal filter 320. The first centrifugal filter 320 is used to centrifugally separate the slurry containing copper oxide crystals discharged from the copper oxide reactor 310. The filter cake outlet of the first centrifugal filter 320 is conveyed to the first dryer 360 for drying through the first conveyor 350, and finally conveyed to the pulverizer 370 for pulverization to obtain active copper oxide with a particle size D90≤10 μm. The filtrate outlet of the first centrifugal filter 320 is connected to the CuO 2 reactor 310 through a pipeline with a mother liquor pump 321. + The chelating recovery device 330 is connected. + The chelate waste liquid outlet of the chelate recoverer 330 is connected to the salt recovery device through a pipeline.

[0035] The salt recovery device includes an evaporation crystallizer 410, a second centrifugal filter 420 and a heat exchanger 430; wherein the feed port of the evaporation crystallizer 410 is connected to the Cu + The chelate waste liquid outlet of the chelate recovery device 330 is connected to remove Cu + The sodium chloride solution is transported to the evaporation crystallizer 410, and the discharge port of the evaporation crystallizer 410 is connected to the second centrifugal filter 420. The tube side inlet and the tube side outlet of the heat exchanger 430 are both connected to the evaporation crystallizer 410, and a second forced circulation pump 440 is also installed on the pipeline connecting the tube side inlet of the heat exchanger 430 and the evaporation crystallizer 410, which is used to circulate heat into the evaporator 410 to evaporate and crystallize the sodium chloride solution.

[0036] The gas outlet at the top of the evaporation crystallizer 410 and the gas outlet at the top of the copper oxide reactor 310 are connected to the shell side inlet 431 of the heat exchanger 430 through a pipeline, and are used to transport the water vapor containing ammonia and the secondary water vapor generated by evaporation and crystallization to the shell side of the heat exchanger 430 to heat the heat exchanger, thereby achieving the purpose of secondary utilization of heat sources and helping to save energy.

[0037] The shell side of the heat exchanger 430 is also provided with a steam outlet 432 and a condensate outlet 433 .

[0038] The ammonia water recovery device includes a condensate collector 510 and an ammonia water recovery tank 520, wherein the tube side inlet of the condensate collector 510 is connected to the steam outlet 432 on the shell side of the heat exchanger 430, the tube side outlet of the condensate collector 510 is connected to the ammonia water collection tank 520, and the condensate outlet 433 on the shell side of the heat exchanger 430 is connected to the ammonia water collection tank 520. After heat exchange in the heat exchanger, the uncondensed ammonia water vapor enters the condensate collector 510 to continue condensing, and the part that has been condensed into a liquid state flows into the ammonia water recovery tank 520. The ammonia water outlet of the ammonia water recovery tank 520 is connected to the tube side of the condensate collector 510 through a reflux pipe with a circulating pump 521, and an ammonia water discharge valve 522 is installed on the reflux pipe for recovering the obtained ammonia water. In addition, the shell layers of the condensate collector 510 and the ammonia water recovery tank 520 are both connected with circulating refrigerant. Specifically, the refrigerant outlet of the refrigerator 530 is first transported to the shell of the ammonia water recovery tank 520 through the refrigerant delivery pump 531, flows out of the shell of the ammonia water collection tank 520, enters the shell of the condensation collector 510, and finally flows back to the refrigerator 530 for refrigeration, thus realizing recycling. During the entire refrigerant circulation process, the refrigerant temperature is stabilized between 0 and 20°C.

[0039] The ammonia water collecting tank 520 is connected to the vacuum pumping device 200, so that the entire system is maintained under negative pressure.

[0040] The method for producing active copper oxide, ammonia and salt (sodium chloride) using the above system comprises the following steps:

[0041] (1) Vacuuming: Turn on the vacuuming device 200 to make the whole system in a negative pressure state. Specifically, the heater shell side of the evaporation crystallizer 410 is in a negative pressure of 0.02-0.04 MPa, and the copper oxide reactor 310 is in a negative pressure of 0.01-0.02 MPa;

[0042] (2) Recovering active copper oxide: Turn on the alkaline solution delivery pump 110, and deliver the alkaline etching waste liquid in the alkaline etching waste liquid storage tank 100 to the filter 120 for filtration. A portion of the filtered filtrate flows back into the alkaline etching waste liquid storage tank 100, and the other portion is fed into the copper oxide reactor 310 at a constant flow rate, and sodium hydroxide is added simultaneously through the alkaline material delivery device 340, and ensure that Na + Excessive amount to fully replace NH in the alkaline etching waste liquid 4 + Under the action of the first forced circulation pump 314 and the spiral separator 315, the Cu in the alkaline etching waste liquid + Formation of Cu(OH) 2 crystals, and transformed into CuO crystals with large surface area at 50-100℃ and oxidation conditions, NH4 + Converted to NH 3 During the rotation process, since the specific gravity of CuO is greater than that of the sodium chloride solution, the slurry containing CuO crystals rotates to the discharge port of the copper oxide reactor 310 and enters the first centrifugal filter 320. The CuO wet product after centrifugal filtration is conveyed to the first dryer 360 for drying by the first conveyor 350, and finally sent to the pulverizer 370 for pulverization to obtain active CuO with a particle size D90 ≤10μm. During the forced circulation process of the above-mentioned materials, the sodium chloride clear liquid separated by the spiral separator 315 is sprayed from the spray mist maker 316 to make NH 3 Rapidly and thoroughly volatilize and separate, and discharge from the top pipe of the copper oxide reactor 310;

[0043] In addition, the mother liquor after the slurry containing CuO crystals is centrifuged from the first centrifugal filter 320 is transported to the Cu + The chelate recovery device 330 recovers Cu by chelation + , the chelated waste liquid is transported to the evaporation crystallizer 410 through a pipeline; in addition, the chelated Cu + Rinse with hydrochloric acid, and recover the rinse liquid into the alkaline etching waste liquid storage tank 100;

[0044] (3) Salt recovery: After the chelated waste liquid entering the evaporation crystallizer 410 is evaporated and dehydrated, the obtained wet sodium chloride product is discharged from the discharge port of the evaporation crystallizer 410 and enters the second centrifugal filter 420. The salt after centrifugal filtration is then conveyed to the second dryer 460 through the second conveyor 450 for drying to obtain finished sodium chloride, and the filtrate is refluxed into the evaporation crystallizer 410;

[0045] (4) Recovering aqueous ammonia: The ammonia vapor generated in the copper oxide reactor 310 and the ammonia vapor generated in the evaporation crystallizer 610 in step (2) are first introduced into the shell side inlet 431 of the heat exchanger 430 to heat the sodium chloride solution flowing through the heat exchanger 430, thereby realizing the secondary utilization of the heat source and achieving the purpose of energy saving;

[0046] After heat exchange, the ammonia vapor and ammonia condensate enter the condensate collector 510 and the ammonia water collection tank 520 through the steam outlet 432 and the condensate outlet 433 on the shell side 430 of the heat exchanger respectively; the refrigerant introduced into the shell side of the condensate collector 510 and the ammonia water collection tank 520 circulates and controls the temperature between 0 and 20°C under the action of the refrigerator 530 and the refrigerant delivery pump 531 to achieve continuous refrigeration; the ammonia water entering the ammonia water collection tank 520 is circulated and refrigerated under the action of the circulating pump 521, and after reaching the output concentration, it is discharged from the ammonia water discharge valve to achieve ammonia water recovery.

[0047] The resource utilization rate of the alkaline etching waste liquid in this embodiment is above 99.9%.

[0048] The present invention uses alkaline etching waste liquid to produce active copper oxide ammonia water and salt system and method, through the active copper oxide recovery device, salt recovery device and ammonia water recovery device combined design and the use of alkaline materials (sodium hydroxide or potassium hydroxide), while generating copper oxide, and also through the metal salt ions (Na + or K + ) replace NH 3 And through physical separation and evaporation crystallization and other methods, the simultaneous recovery of salt and ammonia water is achieved, the alkaline etching waste liquid is completely and comprehensively recycled, the problem of secondary pollution is effectively solved, the utilization rate of hazardous waste resources reaches more than 99.9%, zero pollution emissions are achieved, the problem of secondary hazardous waste is solved, and high-value active copper oxide products and basic chemical products ammonia water and salt are obtained, which have high economic benefits and strong practicality.

[0049] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A system for producing active copper oxide, ammonia and salt using alkaline etching waste liquid, characterized in that: include: Alkaline etching waste liquid storage tank, active copper oxide recovery device, salt recovery device, ammonia recovery device and vacuum device; among which, The active copper oxide recovery device comprises a copper oxide reactor, a first centrifugal filter and a Cu + A chelating recovery device, wherein the feed port of the copper oxide reactor is connected to the alkaline material input device and the alkaline etching waste liquid storage tank, and the discharge port is connected to the first centrifugal filter; a circulating liquid inlet tangent port is opened on one side of the upper part of the copper oxide reactor, and a circulating liquid outlet tangent port is opened on one side of the lower part, and the circulating liquid inlet tangent port and the circulating liquid outlet tangent port are connected through a circulating pipeline with a first forced circulation pump; a spiral separator is also installed on the circulating pipeline, the slurry outlet of the spiral separator is connected to the circulating liquid inlet tangent port, and the clear liquid outlet thereof extends into the copper oxide reactor through a pipeline, and is connected to a spray mist maker; The filtrate outlet of the first centrifugal filter is connected to the Cu + The chelating recovery device is connected, and the Cu + The chelate waste liquid outlet of the chelate recovery device is connected to the salt recovery device; The salt recovery device comprises an evaporative crystallizer and a second centrifugal filter, the feed port of the evaporative crystallizer is connected to the Cu + The chelate waste liquid outlet of the chelate recovery device is connected, and its discharge port is connected to the second centrifugal filter; The ammonia water recovery device comprises a condensation collector and an ammonia water recovery tank, wherein the tube side inlet of the condensation collector is connected to the gas outlet at the top of the copper oxide reactor and the evaporation crystallizer, the tube side outlet of the condensation collector is connected to the ammonia water recovery tank, and the ammonia water recovery tank is connected to the vacuum pumping device; The gas outlet at the top of the copper oxide reactor is connected to the ammonia water recovery device, and the ammonia water recovery device is also connected to the vacuum pumping device; The system further comprises a heat exchanger, wherein the tube side inlet and the tube side outlet of the heat exchanger are respectively connected to the evaporation crystallizer through pipelines, and a second forced circulation pump is also installed on the pipeline connecting the tube side outlet of the heat exchanger and the evaporation crystallizer; The gas outlet at the top of the copper oxide reactor and the gas outlet at the top of the evaporation crystallizer are both connected to the shell inlet of the heat exchanger through a pipeline. The shell outlet of the heat exchanger is also opened with a steam outlet and a condensate outlet. The steam outlet is connected to the pipe side of the condensate collector, and the condensate outlet is connected to the ammonia water recovery tank.

2. A system for producing active copper oxide, ammonia and salt using alkaline etching waste liquid according to claim 1, characterized in that: The water outlet of the ammonia water recovery tank is communicated with the top of the condensation collector through a pipeline with a circulation pump, and an ammonia water discharge valve is installed on the pipeline.

3. A method for producing active copper oxide, ammonia and salt using the system according to any one of claims 1 to 2, characterized in that: The steps include: (1) Vacuuming: Turn on the vacuuming device to put the entire system in a negative pressure state; (2) Recovering active copper oxide: filtering the alkaline etching waste liquid in the alkaline etching waste liquid storage tank and transporting it to the copper oxide reactor, and simultaneously adding an excess of alkaline material to recover the Cu in the alkaline etching waste liquid. + Cu(OH)2 crystals are generated in a copper oxide reactor and converted into CuO crystals at 50-100°C under oxidation conditions. The slurry containing the CuO crystals enters the first centrifugal filter from the outlet of the copper oxide reactor. The CuO wet product after centrifugal filtration is dried and crushed to obtain active CuO. The mother liquor after centrifugation is transported to Cu + Chelating recovery of Cu in the chelating recovery device + , the chelated waste liquid is transported to the evaporation crystallizer through a pipeline; (3) recovering salt: after the chelated waste liquid entering the evaporation crystallizer is evaporated and water is removed, the resulting salt is discharged from the discharge port of the evaporation crystallizer and enters the second centrifugal filter. The salt after centrifugal filtration is then dried to obtain finished salt, and the filtrate is returned to the evaporation crystallizer; (4) Recovering aqueous ammonia: The ammonia vapor generated in the copper oxide reactor and the ammonia vapor generated in the evaporation crystallizer in step (2) are transported to the condensation collector tube side of the aqueous ammonia recovery device through a pipeline, and are recovered as aqueous ammonia after condensation; The step (4) is as follows: the ammonia vapor generated in the copper oxide reactor and the ammonia vapor generated in the evaporation crystallizer in the step (2) are first introduced into the shell side inlet of the heat exchanger, and the ammonia vapor and ammonia condensed water after heat exchange enter the condensate collector and the ammonia water recovery tank respectively through the steam outlet and the condensate outlet on the shell side of the heat exchanger.

Images