Treatment method and device system for recovering nickel from nitrogen trifluoride electrolysis waste residues

Abstract

The invention relates to a treatment method and device system for recycling nickel from nitrogen trifluoride electrolysis waste residues. The device system comprises an electrolytic bath stirring device, a conveying device, a first centrifugal device, a first drying device, a smelting device, a tail gas treatment device and an electrolyte recycling unit. The device system provided by the invention is simple in structure and convenient to operate, can run safely and stably, can recover ammonium bifluoride and crude nickel ingots with the nickel content of 95 wt% or above from the electrolytic bath waste residues, reduces pollutant discharge, greatly reduces the production cost, and has remarkable economic benefits and environmental benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of nitrogen trifluoride preparation, and relates to a method for recycling electrolytic waste residue of nitrogen trifluoride, in particular to a treatment method and device system for recycling nickel from electrolytic waste residue of nitrogen trifluoride. Background Art

[0002] Nitrogen trifluoride is an electronic gas that has developed rapidly in recent years. It is an excellent plasma etching gas in the microelectronics industry and an essential material in the manufacturing processes of the semiconductor and LCD industries. It is mostly used as an etchant for semiconductor materials such as polysilicon, silicon nitride, and tungsten silicide, especially for etching integrated circuit materials with a thickness less than 1.5 μm. It can also play a cleaning role in the production of integrated circuit boards and liquid crystal displays, or be used as a fluorine source for hydrogen fluoride-fluorine high-energy chemical lasers, etc.

[0003] The electrolytic method for preparing nitrogen trifluoride is a continuous production process that generates a large amount of waste residue containing ammonium bifluoride, hydrogen fluoride, nickel fluoride, ferrous fluoride, and ferric fluoride. Due to the relatively large specific gravity of metal fluorides, most of them will deposit at the bottom of the electrolytic cell. During the process of disassembling and inspecting the electrolytic cell, it is necessary to clean the waste residue from the bottom of the electrolytic cell, which brings a series of problems such as heavy metal pollution, waste of nickel resources and electrolyte raw materials, and increased production costs.

[0004] Currently, the methods for recycling and treating electrolytic waste residue of nitrogen trifluoride include chemical precipitation method, electrolysis method, flocculation method, and ion exchange method, etc. Among them, the chemical precipitation method has the characteristics of simple process, low cost, and diverse precipitants, and is suitable for the treatment and recycling of electrolytic waste residue of nitrogen trifluoride with special components. However, the purity of the nickel product obtained by recycling is relatively low, still containing a large amount of fluorine- and ammonia-containing impurities, and the price of the obtained nickel product is relatively low, which cannot effectively reduce the production cost. Although the electrolysis method has high recycling efficiency and good effect, due to the complex composition of the electrolytic waste residue of nitrogen trifluoride, the treatment difficulty is relatively large, and the recycling cost is relatively high. The flocculation method is not conducive to the further recycling and utilization of nickel due to the complex components of the flocculant. The ion exchange method is not suitable for the recycling of nickel with complex composition and high concentration.

[0005] In order to further improve the resource utilization efficiency, reduce environmental pollution and production costs, it is necessary to provide a different treatment method and device system for recycling nickel from electrolytic waste residue of nitrogen trifluoride. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a treatment method and device system for recycling nickel from electrolytic waste residue of nitrogen trifluoride. The treatment method operates in the device system, can fully treat the electrolytic waste residue of nitrogen trifluoride, effectively reduce pollutant emissions, and greatly reduce the production cost, with significant economic and environmental benefits.

[0007] To achieve the object of the present invention, the following technical solutions are adopted in the present invention:

[0008] In a first aspect, the present invention provides a device system for recovering nickel from electrolytic waste residue of nitrogen trifluoride. The device system includes an electrolytic cell stirring device, a conveying device, a first centrifugal device, a first drying device, a smelting device, a tail gas treatment device and an electrolyte recovery unit.

[0009] The electrolytic cell stirring device is used to stir the materials in the electrolytic cell; the conveying device is used to convey the materials in the electrolytic cell to the first centrifugal device; the solid material outlet of the first centrifugal device is connected to the first drying device, and the liquid material outlet of the first centrifugal device is connected to the electrolyte recovery unit; the dried material outlet of the first drying device is connected to the smelting device.

[0010] The waste gas outlets of the first drying device, the smelting device and the electrolytic cell are connected to the tail gas treatment device.

[0011] The electrolyte recovery unit is used to recover ammonium bifluoride.

[0012] The device system provided by the present invention has a simple structure, convenient operation and safe and stable operation. It can fully treat the electrolytic waste residue of nitrogen trifluoride, effectively reduce the emission of pollutants, realize the effective recovery of metallic nickel in the nitrogen trifluoride waste residue, and has high economic value. The recovered ammonium bifluoride can be used as a raw material for preparing nitrogen trifluoride by electrolysis; the slag produced by the smelting device can be used to make rock wool boards or machine-made sand. Therefore, the device system provided by the present invention realizes the recovery and comprehensive utilization of nickel and fluorine resources, effectively reduces the emission of pollutants, greatly reduces the production cost, and has remarkable economic and environmental benefits.

[0013] When applying the device system provided by the present invention:

[0014] (1) Ammonia water is added to the electrolytic cell, and the electrolytic cell stirring device is started to fully dissolve the electrolytic waste residue in the electrolytic cell to obtain a neutralized solution; the neutralized solution in the electrolytic cell is transferred to the first centrifugal device by the conveying device for the first centrifugal treatment to obtain solid materials and liquid materials;

[0015] (2) The main component of the liquid material obtained in step (1) includes an aqueous solution of ammonium bifluoride, and ammonium bifluoride is recovered in the electrolyte recovery unit;

[0016] (3) The solid material obtained in step (1) is subjected to the first drying treatment in the first drying device to obtain a dried residue with a water content of less than 1 wt%; the dried residue is transferred to the smelting device, where it is mixed with a smelting agent for smelting treatment to obtain slag and a crude nickel ingot with a nickel content of more than 95 wt%.

[0017] The order of steps (2) and (3) is not specified.

[0018] The exhaust gas outlets of the first drying device, the smelting device, and the electrolytic cell are used for tail gas treatment in the tail gas treatment device.

[0019] Preferably, the conveying device includes a diaphragm pump.

[0020] Preferably, the electrolyte recovery unit includes a dehydration device, a second centrifugal device, a second drying device, and a vacuum device;

[0021] The liquid material outlet of the first centrifugal device is connected to the feed inlet of the dehydration device;

[0022] The vacuum device is connected to the dehydration device to provide a negative pressure condition for the dehydration device;

[0023] The second centrifugal device and the second drying device are connected in sequence, and the discharge outlet of the dehydration device is connected to the feed inlet of the second centrifugal device.

[0024] The main component of the liquid material obtained in step (1) includes an aqueous solution of ammonium bifluoride. The liquid material is dehydrated and cooled for crystallization in the dehydration device, and then undergoes a second centrifugation treatment in the second centrifugal device; the material after the second centrifugation treatment is dried in the second drying device to obtain the recovered ammonium bifluoride.

[0025] Preferably, the smelting device is a direct current electric furnace.

[0026] Preferably, the tail gas treatment device includes a dust removal device, a desulfurization device, and a tail gas absorption device;

[0027] The exhaust gas outlets of the first drying device and the smelting device are connected to the inlet of the dust removal device. The outlet of the dust removal device is connected to the inlet of the desulfurization device. The outlet of the desulfurization device is connected to the inlet of the tail gas absorption device;

[0028] The exhaust gas outlet of the electrolytic cell is connected to the inlet of the tail gas absorption device.

[0029] Optionally, the dust removal device includes a cyclone dust collector or a high-temperature resistant bag filter.

[0030] Optionally, the desulfurization device includes a conventional semi-dry desulfurization device, including a lime slurry storage tank, a jet pump, a desulfurization scrubbing tower, etc.

[0031] Optionally, the tail gas absorption device includes an absorption tower, a circulating jet pump, a fan, etc.

[0032] Second aspect, the present invention provides a method for treating nickel recovered from electrolytic waste residue of nitrogen trifluoride, and the treatment method is carried out in the device system described in the first aspect, including the following steps:

[0033] (1) Under stirring conditions, use ammonia water to dissolve the electrolytic waste residue in the electrolytic cell to obtain a neutralized solution; the obtained neutralized solution is subjected to a first centrifugation treatment to obtain a solid material and a liquid material;

[0034] (2) The liquid material is subjected to electrolyte recovery to obtain ammonium bifluoride;

[0035] (3) The solid material is first dried to a water content of less than 1 wt%, obtaining a dried residue; the dried residue is mixed with a smelting agent and subjected to a smelting treatment to obtain a slag and a crude nickel ingot;

[0036] Steps (2) and (3) are not in a sequential order;

[0037] The waste gas generated during the treatment method is subjected to tail gas treatment.

[0038] Preferably, the concentration of the ammonia water in step (1) is 5 wt% - 25 wt%, for example, it can be 5 wt%, 10 wt%, 15 wt%, 18 wt%, 20 wt% or 25 wt%, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable, and preferably 15 wt% - 20 wt%.

[0039] Preferably, the pH value of the neutralized solution is 6 - 7.

[0040] Preferably, the rotation speed of the stirring conditions in step (1) is 30 r / min - 50 r / min, for example, it can be 30 r / min, 35 r / min, 40 r / min, 45 r / min or 50 r / min, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0041] Preferably, the stirring time of the stirring conditions in step (1) is 1 h - 2 h, for example, it can be 1 h, 1.2 h, 1.5 h, 1.6 h, 1.8 h or 2 h, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0042] Preferably, the centrifugation speed of the first centrifugation treatment in step (1) is 5000 r / min - 7000 r / min, for example, it can be 5000 r / min, 5500 r / min, 6000 r / min, 6500 r / min or 7000 r / min, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0043] Preferably, the temperature of the first drying in step (3) is 600°C - 800°C. For example, it can be 600°C, 650°C, 700°C, 750°C or 800°C, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable, and preferably it is 700°C - 750°C.

[0044] Preferably, the smelting agent in step (3) includes any one or a combination of at least two of coke, pulverized coal, gypsum or limestone. Typical but non-limiting combinations include the combination of coke and pulverized coal, the combination of pulverized coal and gypsum, the combination of gypsum and limestone, the combination of coke, pulverized coal and gypsum, the combination of pulverized coal, gypsum and limestone, or the combination of coke, pulverized coal, gypsum and limestone.

[0045] Preferably, the temperature of the smelting treatment in step (3) is 1300°C - 1500°C. For example, it can be 1300°C, 1350°C, 1400°C, 1450°C or 1500°C, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable, and preferably it is 1400°C - 1450°C.

[0046] Preferably, the time of the smelting treatment in step (3) is 8h - 16h. For example, it can be 8h, 10h, 12h, 14h, 15h or 16h, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable, and preferably it is 10h - 12h.

[0047] As a preferred technical solution of the second aspect of the present invention, the treatment method includes the following steps:

[0048] (1) Add ammonia water with a concentration of 5wt% - 25wt% to the electrolytic cell, start the stirring device of the electrolytic cell, stir at a speed of 30r / min - 50r / min for 1h - 2h to fully dissolve the electrolytic waste residue in the electrolytic cell to obtain a neutralized solution; use a conveying device to transfer the neutralized solution in the electrolytic cell to a first centrifugal device for a first centrifugal treatment with a centrifugal speed of 5000r / min - 7000r / min to obtain a solid material and a liquid material;

[0049] (2) The main component of the liquid material obtained in step (1) includes an aqueous solution of ammonium bifluoride. The liquid material is subjected to dehydration treatment and cooling crystallization in a dehydration device, and then subjected to a second centrifugal treatment in a second centrifugal device; the material after the second centrifugal treatment is dried in a second drying device to obtain recycled ammonium bifluoride;

[0050] (3) The solid material obtained in step (1) is subjected to a first drying treatment at a temperature of 600°C - 800°C in a first drying device to obtain a dried residue with a water content of 1 wt% or less; the dried residue is transferred to a direct current electric furnace, where it is mixed with a smelting agent and subjected to a smelting treatment at a temperature of 1300°C - 1500°C for 8 h - 16 h to obtain a slag and a crude nickel ingot with a nickel content of 95 wt% or more.

[0051] Step (2) and step (3) are not in a sequential order.

[0052] The waste gas generated by the first drying device and the direct current electric furnace is first subjected to dust removal treatment in a dust removal device, then subjected to desulfurization treatment in a desulfurization device, and finally discharged after being treated by a tail gas absorption device; the waste gas generated in the electrolytic cell is discharged after being treated by the tail gas absorption device.

[0053] The numerical ranges described in the present invention not only include the specific point values exemplified above, but also any point values between the above numerical ranges not exemplified. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the ranges.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The device system provided by the present invention has a simple structure, convenient operation, and safe and stable operation. It can fully treat the nitrogen trifluoride electrolytic waste residue, effectively reduce pollutant emissions, realize the effective recovery of metallic nickel in the nitrogen trifluoride waste residue, and has high economic value. The ammonium bifluoride recovered can be used as a raw material for the preparation of nitrogen trifluoride by electrolysis; the slag generated by the smelting device can be used to make rock wool boards or machine-made sand. Therefore, the device system provided by the present invention realizes the recovery and comprehensive utilization of nickel and fluorine resources, effectively reduces pollutant emissions, greatly reduces production costs, and has significant economic and environmental benefits. Description of the Drawings

[0056] Figure 1 It is a schematic structural diagram of the device system for recovering nickel from nitrogen trifluoride electrolytic waste residue in Example 1 of the present invention.

[0057] Among them: 1, electrolytic cell; 2, electrolytic cell stirring device; 3, conveying device; 4, first centrifugal device; 5, first drying device; 6, direct current electric furnace; 7, dust removal device; 8, desulfurization device; 9, tail gas absorption device; 10, dehydration device; 11, second centrifugal device; 12, second drying device; 13, vacuum device. Detailed Embodiments

[0058] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0059] Embodiment 1

[0060] The present invention provides a device system for recovering nickel from electrolytic waste residue of nitrogen trifluoride, and its structural schematic diagram is as Figure 1 shown, including an electrolytic cell stirring device 2, a conveying device 3, a first centrifugal device 4, a first drying device 5, a smelting device, a tail gas treatment device and an electrolyte recovery unit;

[0061] The electrolytic cell stirring device 2 is used to stir the materials in the electrolytic cell 1; the conveying device 3 is used to convey the materials in the electrolytic cell 1 to the first centrifugal device 4; the solid material outlet of the first centrifugal device 4 is connected to the first drying device 5, and the liquid material outlet of the first centrifugal device 4 is connected to the electrolyte recovery unit; the dried material outlet of the first drying device 5 is connected to the smelting device; the conveying device 3 is a diaphragm pump, and the smelting device is a direct current electric furnace 6.

[0062] The electrolyte recovery unit includes a dehydration device 10, a second centrifugal device 11, a second drying device 12 and a vacuum device 13; the liquid material outlet of the first centrifugal device 4 is connected to the feed inlet of the dehydration device 10; the vacuum device 13 is connected to the dehydration device 10 to provide a negative pressure condition for the dehydration device 10; the second centrifugal device 11 and the second drying device 12 are connected in sequence, and the discharge outlet of the dehydration device 10 is connected to the feed inlet of the second centrifugal device 11; the second drying device 12 obtains ammonium bifluoride through drying and recovery.

[0063] The tail gas treatment device includes a dust removal device 7, a desulfurization device 8 and a tail gas absorption device 9; the exhaust gas outlets of the first drying device 5 and the smelting device are connected to the inlet of the dust removal device 7, the outlet of the dust removal device 7 is connected to the inlet of the desulfurization device 8, and the outlet of the desulfurization device 8 is connected to the inlet of the tail gas absorption device 9; the exhaust gas outlet of the electrolytic cell 1 is connected to the inlet of the tail gas absorption device 9.

[0064] Application Example 1

[0065] This application example provides a treatment method for recovering nickel from electrolytic waste residue of nitrogen trifluoride. The treatment method is carried out in the device system provided in Embodiment 1 and includes the following steps:

[0066] (1) Add 200 Kg of ammonia water with a concentration of 20 wt% to an electrolytic cell containing 200 Kg of nitrogen trifluoride electrolytic waste residue. Start the stirring device of the electrolytic cell and stir at a speed of 40 r / min for 1.5 h to fully dissolve the electrolytic waste residue in the electrolytic cell, obtaining a neutralization solution with a pH of 7. Use a diaphragm pump to transfer the neutralization solution in the electrolytic cell to the first centrifugal device and perform the first centrifugation treatment at a centrifugal speed of 6000 r / min, obtaining 140 Kg of solid material and 260 Kg of liquid material;

[0067] (2) The main component of the liquid material obtained in step (1) is an aqueous solution of ammonium bifluoride. The liquid material is dehydrated in a dehydration device under the conditions of -0.09 MPa and 70 °C. After removing 120 Kg of water, it is cooled and crystallized. After 4 hours of cooling and crystallization, an ammonium bifluoride solid-liquid mixture is obtained. The ammonium bifluoride solid-liquid mixture is subjected to a second centrifugation treatment in a second centrifugal device. The material after the second centrifugation treatment is dried in a second drying device to obtain 60 Kg of ammonium bifluoride that meets the requirements for use as a raw material for the preparation of nitrogen trifluoride by electrolysis;

[0068] (3) The solid material obtained in step (1) is subjected to a first drying treatment at a temperature of 750 °C for 3 h in a first drying device to obtain 126 Kg of dry slag with a water content of less than 1 wt%. The dry slag is transferred to a direct current electric furnace and mixed with 100 Kg of the smelting agent coke therein, and smelted at a temperature of 1450 °C for 10 h to obtain slag and 50 Kg of crude nickel ingot with a nickel content of 96.5 wt%;

[0069] The waste gas generated by the first drying device and the direct current electric furnace is first subjected to dust removal treatment in a dust removal device, then subjected to desulfurization treatment in a desulfurization device, and finally discharged after being treated by a tail gas absorption device; the waste gas generated in the electrolytic cell is discharged after being treated by a tail gas absorption device.

[0070] Application Example 2

[0071] This application example provides a treatment method for recovering nickel from nitrogen trifluoride electrolytic waste residue. The treatment method is carried out in the device system provided in Example 1 and includes the following steps:

[0072] (1) Add 250 Kg of ammonia water with a concentration of 15 wt% to an electrolytic cell containing 200 Kg of nitrogen trifluoride electrolytic waste residue. Start the stirring device of the electrolytic cell and stir at a speed of 30 r / min for 2 h to fully dissolve the electrolytic waste residue in the electrolytic cell, obtaining a neutralization solution with a pH of 6. Use a diaphragm pump to transfer the neutralization solution in the electrolytic cell to the first centrifugal device and perform the first centrifugation treatment at a centrifugal speed of 5000 r / min, obtaining 135 Kg of solid material and 315 Kg of liquid material;

[0073] (2) The main component of the liquid material obtained in step (1) includes an aqueous solution of ammonium bifluoride. The liquid material is dehydrated in a dehydration device under the conditions of -0.086 MPa and 75 °C. After removing 150 Kg of water, it is cooled and crystallized. After 4 hours of cooling and crystallization, an ammonium bifluoride solid-liquid mixture is obtained. The ammonium bifluoride solid-liquid mixture is subjected to a second centrifugation treatment in a second centrifugation device. The material after the second centrifugation treatment is dried in a second drying device to obtain 58 Kg of ammonium bifluoride that meets the requirements for use as a raw material in the electrolytic preparation of nitrogen trifluoride.

[0074] (3) The solid material obtained in step (1) is subjected to a first drying treatment at a temperature of 700 °C for 3 h in a first drying device to obtain 122 Kg of dry slag with a water content of 1 wt% or less. The dry slag is transferred to a direct current electric furnace, where it is mixed with 100 Kg of a smelting agent coke and subjected to a smelting treatment at a temperature of 1400 °C for 12 h to obtain slag and 46 Kg of crude nickel ingots with a nickel content of 96.8 wt%.

[0075] The waste gas generated by the first drying device and the direct current electric furnace is first subjected to dust removal treatment in a dust removal device, then subjected to desulfurization treatment in a desulfurization device, and finally discharged after being treated by a tail gas absorption device. The waste gas generated in the electrolytic cell is discharged after being treated by a tail gas absorption device.

[0076] Application Example 3

[0077] This application example provides a method for treating nickel recovered from electrolytic waste slag of nitrogen trifluoride. The treatment method is carried out in the device system provided in Example 1 and includes the following steps:

[0078] (1) 400 Kg of ammonia water with a concentration of 10 wt% is added to an electrolytic cell containing 200 Kg of electrolytic waste slag of nitrogen trifluoride. The stirring device of the electrolytic cell is started and stirred at a speed of 50 r / min for 1 h to fully dissolve the electrolytic waste slag in the electrolytic cell, obtaining a neutralization solution with a pH of 6. The neutralization solution in the electrolytic cell is transferred to a first centrifugation device by a diaphragm pump and subjected to a first centrifugation treatment with a centrifugal speed of 7000 r / min to obtain 130 Kg of solid material and 470 Kg of liquid material.

[0079] (2) The main component of the liquid material obtained in step (1) includes an aqueous solution of ammonium bifluoride. The liquid material is dehydrated in a dehydration device under the conditions of -0.096 MPa and 65 °C. After removing 230 Kg of water, it is cooled and crystallized. After 4 hours of cooling and crystallization, an ammonium bifluoride solid-liquid mixture is obtained. The ammonium bifluoride solid-liquid mixture is subjected to a second centrifugation treatment in a second centrifugation device. The material after the second centrifugation treatment is dried in a second drying device to obtain 55 Kg of ammonium bifluoride that meets the requirements for use as a raw material in the electrolytic preparation of nitrogen trifluoride.

[0080] (3) The solid material obtained in step (1) is subjected to a first drying treatment at a temperature of 600 °C for 3 h in a first drying device to obtain 118 Kg of dry slag with a water content of 1 wt% or less; the dry slag is transferred to a direct current electric furnace, where it is mixed with 100 Kg of a smelting agent coke and subjected to a smelting treatment at a temperature of 1300 °C for 16 h to obtain slag and 42 Kg of crude nickel ingot with a nickel content of 96.7 wt%.

[0081] The waste gas generated by the first drying device and the direct current electric furnace is first subjected to dust removal treatment in a dust removal device, then to desulfurization treatment in a desulfurization device, and finally discharged after being treated by a tail gas absorption device; the waste gas generated in the electrolytic cell is discharged after being treated by a tail gas absorption device.

[0082] Application Example 4

[0083] This application example provides a method for treating nickel recovered from nitrogen trifluoride electrolysis waste residue. The treatment method is carried out in the device system provided in Example 1 and includes the following steps:

[0084] (1) 160 Kg of ammonia water with a concentration of 25 wt% is added to an electrolytic cell containing 200 Kg of nitrogen trifluoride electrolysis waste residue. The stirring device of the electrolytic cell is started and stirred at a speed of 50 r / min for 1 h to fully dissolve the electrolysis waste residue in the electrolytic cell to obtain a neutralization solution with a pH of 7; the neutralization solution in the electrolytic cell is transferred to a first centrifugation device by a diaphragm pump and subjected to a first centrifugation treatment at a centrifugation speed of 7000 r / min to obtain 142 Kg of solid material and 218 Kg of liquid material.

[0085] (2) The main component of the liquid material obtained in step (1) is an aqueous solution of ammonium bifluoride. The liquid material is subjected to dehydration treatment in a dehydration device under the conditions of -0.096 MPa and 65 °C. After removing 105 Kg of water, it is cooled and crystallized. After 4 hours of cooling and crystallization, a solid-liquid mixture of ammonium bifluoride is obtained; the solid-liquid mixture of ammonium bifluoride is subjected to a second centrifugation treatment in a second centrifugation device; the material after the second centrifugation treatment is dried in a second drying device to obtain 62 Kg of ammonium bifluoride that meets the usage requirements of the raw material for preparing nitrogen trifluoride by electrolysis.

[0086] (3) The solid material obtained in step (1) is subjected to a first drying treatment at a temperature of 800 °C for 3 h in a first drying device to obtain 133 Kg of dry slag with a water content of 1 wt% or less; the dry slag is transferred to a direct current electric furnace, where it is mixed with 100 Kg of a smelting agent coke and subjected to a smelting treatment at a temperature of 1500 °C for 8 h to obtain slag and 51 Kg of crude nickel ingot with a nickel content of 96.1 wt%.

[0087] The waste gas generated by the first drying device and the DC electric furnace is first subjected to dust removal treatment in the dust removal device, then desulfurization treatment in the desulfurization device, and finally discharged after being treated by the tail gas absorption device; the waste gas generated in the electrolytic cell is discharged after being treated by the tail gas absorption device.

[0088] In summary, the device system provided by the present invention has a simple structure, convenient operation, and safe and stable operation. It can fully treat the electrolytic waste residue of nitrogen trifluoride, effectively reduce the emission of pollutants, realize the effective recovery of metallic nickel in the nitrogen trifluoride waste residue, and has high economic value. The recovered ammonium bifluoride can be used as a raw material for the preparation of nitrogen trifluoride by electrolysis; the slag generated by the melting device can be used to make rock wool boards or manufactured sand. Therefore, the device system provided by the present invention realizes the recovery and comprehensive utilization of nickel and fluorine resources, effectively reduces the emission of pollutants, greatly reduces the production cost, and has remarkable economic and environmental benefits.

[0089] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived within the technical scope disclosed by the present invention by those skilled in the art all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A device system for recovering nickel from nitrogen trifluoride electrolysis waste residue, characterized in that: The device system includes an electrolytic tank stirring device, a conveying device, a first centrifugal device, a first drying device, a smelting device, a tail gas treatment device and an electrolyte recovery unit; The electrolytic tank stirring device is used to stir the material in the electrolytic tank; the conveying device is used to convey the material in the electrolytic tank to the first centrifugal device; the solid material outlet of the first centrifugal device is connected to the first drying device, and the liquid material outlet of the first centrifugal device is connected to the electrolyte recovery unit; the dry material outlet of the first drying device is connected to the smelting device; The exhaust gas outlets of the first drying device, the smelting device and the electrolytic cell are connected to the tail gas treatment device; The electrolyte recovery unit is used to recover ammonium bifluoride.

2. The device system according to claim 1, characterized in that: The electrolyte recovery unit includes a dehydration device, a second centrifugal device, a second drying device and a vacuum device; The liquid material outlet of the first centrifugal device is connected to the feed inlet of the dehydration device; The vacuum device is connected to the dehydration device and is used to provide negative pressure conditions for the dehydration device; The second centrifugal device is connected to the second drying device in sequence, and the discharge port of the dehydration device is connected to the feed port of the second centrifugal device.

3. The device system according to claim 1 or 2, characterized in that: The smelting device is a direct current furnace.

4. The device system according to any one of claims 1 to 3, characterized in that: The tail gas treatment device includes a dust removal device, a desulfurization device and a tail gas absorption device; The exhaust gas outlet of the first drying device and the smelting device is connected to the air inlet of the dust removal device, the air outlet of the dust removal device is connected to the air inlet of the desulfurization device, and the air outlet of the desulfurization device is connected to the air inlet of the tail gas absorption device; The exhaust gas outlet of the electrolytic cell is connected to the air inlet of the tail gas absorption device.

5. A method for recovering nickel from nitrogen trifluoride electrolysis waste residue, characterized in that: The processing method is carried out in the device system according to any one of claims 1 to 4, comprising the following steps: (1) using aqueous ammonia to dissolve the electrolytic waste residue in the electrolytic cell under stirring conditions to obtain a neutralized solution; the obtained neutralized solution is subjected to a first centrifugal treatment to obtain a solid material and a liquid material; (2) the liquid material is recovered through electrolyte to obtain ammonium bifluoride; (3) the solid material is first dried to a moisture content of less than 1 wt % to obtain dry slag; the dry slag is mixed with a smelting agent and smelted to obtain slag and crude nickel ingots; The steps (2) and (3) are performed in no particular order; The waste gas generated during the treatment method is subjected to tail gas treatment.

6. The processing method according to claim 5, characterized in that: The concentration of the aqueous ammonia in step (1) is 5wt%-25wt%, preferably 15wt%-20wt%; Preferably, the pH value of the neutralization solution is 6-7.

7. The processing method according to claim 5 or 6, characterized in that: The stirring speed in step (1) is 30 rpm to 50 rpm. Preferably, the stirring time of the stirring conditions in step (1) is 1 h to 2 h.

8. The processing method according to any one of claims 5 to 7, characterized in that: The centrifugal speed of the first centrifugal treatment in step (1) is 5000 r / min-7000 r / min; Preferably, the temperature of the first drying in step (3) is 600°C-800°C, preferably 700°C-750°C.

9. The processing method according to any one of claims 5 to 8, characterized in that: The smelting agent in step (3) includes any one of coke, coal powder, gypsum or limestone, or a combination of at least two thereof; Preferably, the temperature of the smelting treatment in step (3) is 1300°C-1500°C, preferably 1400°C-1450°C; Preferably, the smelting treatment time in step (3) is 8h-16h, preferably 10h-12h.

10. The processing method according to any one of claims 5 to 9, characterized in that: The processing method comprises the following steps: (1) adding ammonia water with a concentration of 5wt%-25wt% to the electrolytic cell, starting the electrolytic cell stirring device, stirring at a speed of 30r / min-50r / min for 1h-2h to fully dissolve the electrolytic waste residue in the electrolytic cell to obtain a neutralized solution; using a conveying device to transfer the neutralized solution in the electrolytic cell to a first centrifugal device, performing a first centrifugal treatment at a centrifugal speed of 5000r / min-7000r / min, and obtaining a solid material and a liquid material; (2) The main component of the liquid material obtained in step (1) includes an aqueous solution of ammonium bifluoride, the liquid material is subjected to dehydration treatment and cooling crystallization in a dehydration device, and then subjected to a second centrifugal treatment in a second centrifugal device; the material after the second centrifugal treatment is dried in a second drying device to obtain recovered ammonium bifluoride; (3) The solid material obtained in step (1) is subjected to a first drying treatment at a temperature of 600° C. to 800° C. in a first drying device to obtain a dried slag having a water content of less than 1 wt %; the dried slag is transferred to a DC electric furnace, mixed with a smelting agent, and subjected to a smelting treatment at a temperature of 1300° C. to 1500° C. for 8 h to 16 h to obtain a slag and a crude nickel ingot having a nickel content of more than 95 wt %; The steps (2) and (3) are performed in no particular order; The waste gas generated by the first drying device and the DC electric furnace is first subjected to dust removal treatment in a dust removal device, then subjected to desulfurization treatment in a desulfurization device, and finally subjected to treatment by a tail gas absorption device and discharged externally; the waste gas generated in the electrolytic cell is subjected to treatment by a tail gas absorption device and discharged externally.

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