Process and system for concentrating and removing fluorine and chlorine from nickel-cobalt smelting waste sulfuric acid

Abstract

The invention discloses a nickel-cobalt smelting waste sulfuric acid concentration and fluorine and chlorine removal process and system, and the process comprises the following steps: preheating waste sulfuric acid, then evaporating and concentrating to 70-75wt%, blowing and absorbing the waste sulfuric acid by hot air at 130-150 DEG C in a desorption tower to obtain concentrated sulfuric acid, discharging the hot air from the top of the desorption tower, introducing the hot air into an absorption tower, and spraying and absorbing the hot air by using a calcium hydroxide solution; calcium fluoride solid and a calcium chloride solution are obtained. The system comprises a preheating system, an evaporation and concentration system, a desorption tower, an absorption tower and a vacuum system. The process is simple, the concentration of treated sulfuric acid is large, the fluorine and chlorine recovery rate is high, and fluorine and chlorine separation can be completed in one step; in addition, the system disclosed by the invention has the characteristics of reasonable design, energy conservation and environment-friendly treatment process.

Description

Technical Field

[0001] The invention relates to a waste sulfuric acid recovery and treatment process and system, in particular to a nickel-cobalt smelting waste sulfuric acid concentration and defluorination and chlorination process and system. Background Art

[0002] Cobalt-nickel hydrometallurgy usually consists of three major steps: acid leaching and dissolution, extraction and impurity removal, and cobalt-nickel separation. During the production process, a large amount of dilute sulfuric acid with a concentration of 5-15% is produced. The concentration of F in the dilute sulfuric acid is 0.5-5g / L, the concentration of Cl is 0.5-12g / L, the concentration of arsenic ions is 0.5-1g / L, and the concentration of other metal ions is 20-100mg / L (Zn, Fe, Ca, etc.).

[0003] Therefore, the waste sulfuric acid produced by cobalt-nickel hydrometallurgy is extremely harmful and has high treatment costs, which has always been a major problem plaguing cobalt-nickel smelting companies.

[0004] Chinese patent CN108083231A introduces a method for separating hydrofluoric acid from fluorine-containing sulfuric acid, which is to continuously pass steam into a fluorine-containing sulfuric acid kettle, and what is finally left in the kettle is fluorine-free sulfuric acid. The generated gas is cooled to obtain hydrofluoric acid without sulfuric acid. Although this method can separate hydrofluoric acid, its disadvantages are: high processing cost, high energy consumption, low concentration of sulfuric acid output, low actual defluorination rate, and no effective separation of chloride ions.

[0005] In order to improve the economic efficiency of defluorination concentration of waste sulfuric acid, reduce the waste of sulfuric acid resources and fluorine and chlorine resources, and reduce the energy consumption of sulfuric acid defluorination concentration, it is necessary to improve the sulfuric acid defluorination concentration process and system. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a process and system for concentrating and removing fluorine and chlorine from waste sulfuric acid in nickel-cobalt smelting. The process of the present invention is simple, the concentration of treated sulfuric acid is large, the recovery rate of fluorine and chlorine is high, and the separation of fluorine and chlorine can be completed in one step; in addition, the system of the present invention has the characteristics of reasonable design, energy saving and environmental protection in the treatment process.

[0007] One of the technical solutions of the present invention:

[0008] A process for concentrating and defluorinating waste sulfuric acid from nickel-cobalt smelting is provided, comprising the following steps:

[0009] S1. introducing waste sulfuric acid into a preheating system to preheat waste sulfuric acid;

[0010] S2. The preheated waste sulfuric acid is introduced into the evaporation concentration system for circulation concentration until a fluorine-containing chlorine-containing concentrated sulfuric acid having a sulfuric acid concentration of 70-75% is obtained;

[0011] S3. The fluorine-containing chlorine-containing concentrated sulfuric acid is introduced into the top of the desorption tower and sprayed down, and the hot air at a temperature of 130-150 ° C is blown and absorbed through the bottom, and the concentrated sulfuric acid is discharged from the bottom;

[0012] S4. The hot air that absorbs fluorine and chlorine is discharged from the top of the desorption tower and then introduced into the absorption tower, and calcium hydroxide solution is sprayed from the top of the absorption tower. The air after absorption is directly discharged, and the solid-liquid mixture below is separated by solid-liquid separation to obtain calcium fluoride solid and calcium chloride solution.

[0013] Through the process of this scheme, waste dilute sulfuric acid can be concentrated, defluorinated and dechlorinated, and the separate recovery of sulfuric acid, fluorine and chlorine is realized. The process is simple and the economic benefit is high. The key of this process is: first, the dilute sulfuric acid is concentrated to 70-75%, and then hot air is used to blow off and recover fluorine and chlorine. At this time, the defluorination rate is the highest, because when the concentration is too low, the fluorine in the solution is difficult to be blown off, and when the concentration is too high, fluorosulfonic acid is easily formed, which is also difficult to blow off. Therefore, this application first concentrates the dilute sulfuric acid to 70-75%, and then blows it off with hot air, which greatly improves the removal rate of fluorine and chlorine, and at the same time, the sulfuric acid is concentrated to achieve the recovery and utilization of sulfuric acid.

[0014] Preferably, in the aforementioned nickel-cobalt smelting waste sulfuric acid concentration and defluorination and chlorination process, the heat source of the preheating system is the low-temperature steam discharged from the service side of the evaporation concentration system and / or the concentrated sulfuric acid discharged from the stripping tower.

[0015] This solution further recovers waste heat, reduces energy consumption, and lowers processing costs by using low-temperature steam discharged from the service side of the evaporation and concentration system and / or concentrated sulfuric acid discharged from the stripping tower as the heat source for the preheating system.

[0016] Preferably, in the aforementioned nickel-cobalt smelting waste sulfuric acid concentration and defluorination and chlorination process, the secondary steam generated by the evaporation and concentration system is introduced into the absorption tower together with the hot air discharged from the desorption tower after condensation treatment.

[0017] This solution reduces the loss of fluorine and chlorine by introducing secondary steam into the absorption tower for treatment, and further improves the recovery rate of fluorine and chlorine.

[0018] Preferably, in the aforementioned process for concentrating and defluorinating chlorine from waste sulfuric acid from nickel-cobalt smelting, the hot air is dry hot air.

[0019] This solution uses dry hot air for stripping, which reduces the introduction of external moisture, ensures the concentration of sulfuric acid in the stripping tower, and thus ensures a high defluorination rate.

[0020] The second technical solution of the present invention:

[0021] Provided is a system for concentrating and defluorinating chlorine from waste sulfuric acid in nickel-cobalt smelting, comprising a waste sulfuric acid inlet, the waste sulfuric acid inlet is connected to a preheating system, the preheating system is connected to an evaporation and concentration system, the evaporation and concentration system is connected to a stripping tower, the stripping tower is connected to an absorption tower, and the absorption tower is connected to a vacuum system; a service side steam inlet is provided on the evaporation and concentration system, a liquid inlet end of the evaporation and concentration system is connected to a liquid outlet end of the preheating system, and a liquid outlet end of the evaporation and concentration system is connected to a liquid inlet end of the stripping tower; a concentrated sulfuric acid outlet and a hot air inlet are connected to the bottom of the stripping tower, and the top of the stripping tower is connected to the absorption tower; a sodium hydroxide solution inlet and an air outlet are connected to the top of the absorption tower, and a filter press is connected to the bottom, and a calcium fluoride extraction outlet and a calcium chloride solution outlet are provided on the filter press.

[0022] The system of this scheme is a supporting equipment for realizing the above-mentioned process. Through the system of this scheme, the concentration and defluorination and dechlorination operations of waste dilute sulfuric acid can be realized, and concentrated sulfuric acid, calcium fluoride and calcium chloride can be produced respectively. The design is reasonable and can be promoted and implemented on an industrial scale.

[0023] Preferably, in the aforementioned nickel-cobalt smelting waste sulfuric acid concentration and defluorination and chlorination system, the preheating system consists of a primary preheater and a secondary preheater connected in series; wherein the service side liquid inlet of the primary preheater is connected to the liquid discharge port of the stripping tower, and the concentrated sulfuric acid discharge port is connected to the service side liquid outlet of the primary preheater; the service side air inlet of the secondary preheater is connected to the low-temperature steam discharge port of the evaporation and concentration system, and the service side exhaust port of the secondary preheater is connected to the condensed water discharge port.

[0024] The preheating system of this scheme adopts a primary and secondary preheater connected in series, and improves the preheating effect through a two-stage preheating method; and the primary and secondary preheaters respectively use concentrated sulfuric acid and low-temperature steam discharged from the system as heat sources, which further reduces energy loss, saves energy consumption, and reduces processing costs.

[0025] Preferably, in the aforementioned nickel-cobalt smelting waste sulfuric acid concentration and defluorination and chlorination system, the evaporation and concentration system consists of a first-effect evaporation concentrator, a second-effect evaporation concentrator and a third-effect evaporation concentrator connected in series.

[0026] This solution forms an evaporation and concentration system by connecting three groups of evaporation concentrators in series, which has higher evaporation and concentration efficiency, higher concentration and better concentration effect.

[0027] Preferably, in the aforementioned nickel-cobalt smelting waste sulfuric acid concentration and defluorination and chlorination system, the first-effect evaporation concentrator includes a first-effect heater and a first-effect separation chamber; the second-effect evaporation concentrator includes a second-effect heater and a second-effect separation chamber; the triple-effect evaporation concentrator includes a triple-effect heater and a triple-effect separation chamber respectively; the exhaust end of the first-effect separation chamber is connected to the service side air inlet of the second-effect heater, the exhaust end of the second-effect separation chamber is connected to the service side air inlet of the triple-effect heater, and the exhaust end of the triple-effect separation chamber is connected to the absorption tower.

[0028] This solution uses the secondary steam of the separation chamber of the previous stage as the heat source of the heater of the next stage, so the design is more reasonable, more energy-saving and lower in cost.

[0029] Preferably, in the aforementioned nickel-cobalt smelting waste sulfuric acid concentration and defluorination and chlorination system, the first-effect evaporation concentrator, the second-effect evaporation concentrator and the third-effect evaporation concentrator are all forced circulation evaporation structures.

[0030] The evaporation concentrator of this scheme is a forced circulation evaporation, which can further improve the effect of evaporation and concentration, and the sulfuric acid concentration is higher.

[0031] Preferably, in the aforementioned nickel-cobalt smelting waste sulfuric acid concentration and defluorination and chlorination system, a condenser is provided between the exhaust end of the three-effect separation chamber and the absorption tower, the service side of the condenser is provided with a condensate upper inlet and a condensate lower inlet, the discharge end of the condenser is connected to a wastewater collecting tank, and the wastewater collecting tank is provided with a wastewater discharge pipe; the wastewater collecting tank is connected to the service side discharge ports of the two-effect heater and the three-effect heater.

[0032] This solution condenses the secondary steam of the evaporation concentration system by setting up a condenser, and uses a wastewater collection tank to collect wastewater in the condenser and wastewater in the second-effect heater and the third-effect heater. The design is reasonable and environmentally friendly.

[0033] Beneficial effects of the present invention:

[0034] 1. The process of the present invention can concentrate, defluorinate and dechlorinate waste dilute sulfuric acid, realize the separate recovery of sulfuric acid, fluorine and chlorine, and has simple process and high economic benefit.

[0035] 2. The process of the present invention further recovers waste heat, reduces energy consumption and reduces processing costs by using low-temperature steam discharged from the service side of the evaporation and concentration system and / or concentrated sulfuric acid discharged from the stripping tower as the heat source of the preheating system.

[0036] 3. The process of the present invention reduces the loss of fluorine and chlorine by introducing secondary steam into the absorption tower for treatment, and further improves the recovery rate of fluorine and chlorine.

[0037] 4. The process of the present invention adopts dry hot air for stripping, thereby reducing the introduction of external moisture, ensuring the concentration of sulfuric acid in the stripping tower, and further ensuring a high defluorination rate.

[0038] 5. The system of the present invention can realize the concentration and defluorination and dechlorination operations of waste dilute sulfuric acid, and respectively produce concentrated sulfuric acid, calcium fluoride and calcium chloride. The design is reasonable and can be promoted and implemented industrially.

[0039] 6. The preheating system of the present invention is composed of a primary and a secondary preheater connected in series, and the preheating effect is improved by a two-stage preheating method; and the primary and secondary preheaters respectively use concentrated sulfuric acid and low-temperature steam discharged from the system as heat sources, which further reduces energy loss, saves energy consumption, and reduces processing costs.

[0040] 7. The present invention forms an evaporation and concentration system by connecting three groups of evaporation concentrators in series, which has higher evaporation and concentration efficiency, higher concentration and better concentration effect. At the same time, the system of the present invention uses the secondary steam of the separation chamber of the previous stage as the heat source of the heater of the next stage, so the design is more reasonable, more energy-saving and lower in cost.

[0041] 8. The system of the present invention condenses the secondary steam of the evaporation concentration system by setting a condenser, and uses a wastewater collection tank to collect wastewater in the condenser and wastewater in the second-effect heater and the third-effect heater. The design is reasonable and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Attached Figure 1 It is a structural schematic diagram of the system of the present invention;

[0043] Attached Figure 2 It is a structural schematic diagram of the evaporation concentration system of the system of the present invention.

[0044] Explanation of the reference numerals: 1-waste sulfuric acid inlet, 2-preheating system, 3-evaporation concentration system, 4-service side steam inlet, 5-stripping tower, 6-absorption tower, 7-vacuum system, 8-sodium hydroxide solution inlet, 9-air outlet, 10-filter press, 11-calcium fluoride extraction outlet, 12-calcium chloride solution outlet, 13-concentrated sulfuric acid outlet, 14-primary preheater, 15-secondary preheater, 16-condensate outlet, 17-condenser, 18-condensate upper water inlet, 19-condensate lower water inlet, 20-wastewater collection tank, 21-wastewater discharge pipe, 22-first-effect evaporation concentrator, 221-first-effect heater, 222-first-effect separation chamber, 23-second-effect evaporation concentrator, 231-second-effect heater, 232-second-effect separation chamber, 24-triple-effect evaporation concentrator, 241-triple-effect heater, 242-triple-effect separation chamber, 25-hot air inlet. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the embodiments, but they are not intended to limit the present invention.

[0046] Embodiments of the present invention

[0047] Example 1

[0048] A process for concentrating and defluorinating waste sulfuric acid from nickel-cobalt smelting, comprising the following steps:

[0049] S1. The waste dilute sulfuric acid from nickel-cobalt smelting having a concentration of 10wt% is introduced into the preheating system for heating to obtain preheated waste sulfuric acid;

[0050] S2. The preheated waste sulfuric acid is introduced into the evaporation concentration system for circulation concentration until a fluorine-containing chlorine-containing concentrated sulfuric acid having a sulfuric acid concentration of 72wt% is obtained;

[0051] S3. The fluorine-containing chlorine-containing concentrated sulfuric acid is introduced into the top of the desorption tower and sprayed down, and the dry hot air at a temperature of 150°C is blown and absorbed through the bottom, and the concentrated sulfuric acid is discharged from the bottom; at this time, the fluorine content in the concentrated sulfuric acid is less than 100 mg / L, and the chlorine content is less than 80 mg / L;

[0052] S4. The hot air that absorbs fluorine and chlorine is discharged from the top of the desorption tower and then introduced into the absorption tower, and calcium hydroxide solution is sprayed from the top of the absorption tower. The air after absorption is directly discharged, and the solid-liquid mixture below is separated by solid-liquid separation to obtain calcium fluoride solid and calcium chloride solution.

[0053] The arsenic content in the exhausted air of this embodiment is less than 0.4 mg / m 3 , the content of sulfuric acid mist is less than 40mg / m 3 、Chloride ion content is less than 60mg / m 3 , the content of hydrogen chloride is less than 80mg / m 3 、The fluoride content is less than 3.0mg / m 3 .

[0054] Example 2

[0055] A process for concentrating and defluorinating waste sulfuric acid from nickel-cobalt smelting, comprising the following steps:

[0056] S1. The waste dilute sulfuric acid from nickel-cobalt smelting having a concentration of 5wt% is introduced into the preheating system for heating to obtain preheated waste sulfuric acid;

[0057] S2. The preheated waste sulfuric acid is introduced into the evaporation concentration system for circulation concentration until a fluorine-containing chlorine-containing concentrated sulfuric acid having a sulfuric acid concentration of 70wt% is obtained;

[0058] S3. The fluorine-containing chlorine-containing concentrated sulfuric acid is introduced into the top of the desorption tower and sprayed down, and the dry hot air at a temperature of 140°C is blown and absorbed through the bottom, and the concentrated sulfuric acid is discharged from the bottom. The discharged hot concentrated sulfuric acid is used as the heat source of the S1 preheating system;

[0059] S4. The hot air that absorbs fluorine and chlorine is discharged from the top of the desorption tower and then introduced into the absorption tower, and calcium hydroxide solution is sprayed from the top of the absorption tower. The air after absorption is directly discharged, and the solid-liquid mixture below is separated by solid-liquid separation to obtain calcium fluoride solid and calcium chloride solution.

[0060] Example 3

[0061] A process for concentrating and defluorinating waste sulfuric acid from nickel-cobalt smelting, comprising the following steps:

[0062] S1. The waste dilute sulfuric acid from nickel-cobalt smelting having a concentration of 15wt% is introduced into the preheating system for heating to obtain preheated waste sulfuric acid;

[0063] S2. The preheated waste sulfuric acid is introduced into the evaporation concentration system for circulation concentration until a fluorine-containing chlorine-containing concentrated sulfuric acid with a sulfuric acid concentration of 75wt% is obtained; the low-temperature steam discharged from the service side of the evaporation concentration system is used as the heat source of the S1 preheating system;

[0064] S3. The fluorine-containing chlorine-containing concentrated sulfuric acid is introduced into the top of the desorption tower and sprayed down, and the dry hot air at a temperature of 160°C is blown and absorbed through the bottom, and the concentrated sulfuric acid is discharged from the bottom;

[0065] S4. After the hot air that absorbs fluorine and chlorine is discharged from the top of the desorption tower, it is introduced into the absorption tower together with the secondary steam generated by the evaporation and concentration system after condensation treatment, and calcium hydroxide solution is sprayed from the top of the absorption tower. The air after absorption treatment is directly discharged, and the solid-liquid mixture below is separated by solid-liquid separation to obtain calcium fluoride solid and calcium chloride solution.

[0066] Example 4

[0067] A system for concentrating and defluorinating waste sulfuric acid from nickel and cobalt smelting, as shown in the attached Figure 1-2 As shown, it includes a waste sulfuric acid inlet 1, which is connected to a storage tank of waste sulfuric acid, the waste sulfuric acid inlet 1 is connected to a preheating system 2, the preheating system 2 is connected to an evaporation and concentration system 3, the evaporation and concentration system 3 is connected to a desorption tower 5, the desorption tower 5 is connected to an absorption tower 6, and the absorption tower 6 is connected to a vacuum system 7; wherein the preheating system 2, the evaporation and concentration system 3, the desorption tower 5 and the absorption tower 6 are airtightly connected via pipelines, and a vacuum environment is provided inside by the vacuum system 7;

[0068] The evaporation and concentration system 3 is provided with a service side steam inlet 4, which is connected to an external steam generator to provide high-temperature steam for heating in the evaporation and concentration system 3. The liquid inlet end of the evaporation and concentration system 3 is connected to the liquid outlet end of the preheating system 2, and the liquid outlet end of the evaporation and concentration system 3 is connected to the liquid inlet end of the desorption tower 5.

[0069] The bottom of the stripping tower 5 is connected to a concentrated sulfuric acid outlet 13 and a hot air inlet 25, the hot air inlet 25 is connected to an external hot air generator, and the top of the stripping tower 5 is connected to the absorption tower 6;

[0070] The top of the absorption tower 6 is connected to a sodium hydroxide solution inlet 8 and an air outlet 9, and the bottom is connected to a filter press 10, and the filter press 10 is provided with a calcium fluoride extraction outlet 11 and a calcium chloride solution outlet 12.

[0071] When the system of this embodiment is in use, the waste dilute sulfuric acid first enters the preheating system 2 through the waste sulfuric acid inlet 1 for heating to obtain preheated waste sulfuric acid; the preheated waste sulfuric acid is discharged from the preheating system 2 and then enters the evaporation and concentration system 3 through a pipeline. Under the action of high-temperature steam provided by the service side, the preheated waste sulfuric acid is further heated to evaporate most of the water therein, thereby obtaining concentrated fluorine-containing chlorine-containing concentrated sulfuric acid; the fluorine-containing chlorine-containing concentrated sulfuric acid is discharged from the evaporation and concentration system 3, and then sent to the top of the desorption tower 5 through a pipeline, and sprayed down through a conventional nozzle, and the bottom is sent through the hot air inlet 25 is blown with dry hot air, so that the fluorine and chlorine in the concentrated sulfuric acid are absorbed by the blowing gas, and the pure concentrated sulfuric acid is discharged from the bottom; the hot air that absorbs the fluorine and chlorine is discharged from the top of the desorption tower 5 and then sent to the absorption tower 6 through a pipeline, and the calcium hydroxide solution is sprayed into the sodium hydroxide solution inlet 8 at the top of the absorption tower 6. The calcium hydroxide solution absorbs and reacts with the gas in the absorption tower 6 after contacting, generating calcium fluoride precipitation and calcium chloride solution, and the air after absorption is directly discharged, and the solid-liquid mixture below enters the filter press 10 for filter pressing to obtain calcium fluoride solid and calcium chloride solution.

[0072] Further implementation examples include Figure 1-2 As shown, the preheating system 2 is composed of a primary preheater 14 and a secondary preheater 15 connected in series; wherein the service side liquid inlet of the primary preheater 14 is connected to the liquid discharge port of the stripping tower 5, and the concentrated sulfuric acid discharge port 13 is connected to the service side liquid outlet of the primary preheater 14; the service side air inlet of the secondary preheater 15 is connected to the low-temperature steam discharge port of the evaporation and concentration system 3, and the service side exhaust port of the secondary preheater 15 is connected to the condensed water discharge port 16.

[0073] In this embodiment, when the high-temperature concentrated sulfuric acid is discharged from the desorption tower 5, it first passes through the primary preheater 14, and the cold waste dilute sulfuric acid in the primary preheater 14 is preheated for the first time to recover the heat of the high-temperature concentrated sulfuric acid, and then discharged through the concentrated sulfuric acid outlet 13; and the low-temperature steam discharged from the evaporation concentration system 3 enters the secondary preheater 15, and the waste dilute sulfuric acid that has undergone the primary preheating treatment is preheated for the second time, thereby recovering the heat in the low-temperature steam.

[0074] Further implementation examples include Figure 1-2As shown, the evaporation and concentration system 3 is composed of a first-effect evaporation concentrator 22, a second-effect evaporation concentrator 23 and a third-effect evaporation concentrator 24 connected in series.

[0075] In this embodiment, the first-effect evaporation concentrator 22, the second-effect evaporation concentrator 23 and the third-effect evaporation concentrator 24 can be connected in series according to the conventional connection method of the third-effect evaporation system.

[0076] Further implementation examples include Figure 1-2 As shown, the first-effect evaporation concentrator 22 includes a first-effect heater 221 and a first-effect separation chamber 222; the second-effect evaporation concentrator 23 includes a second-effect heater 231 and a second-effect separation chamber 232; the triple-effect evaporation concentrator 24 includes a triple-effect heater 241 and a triple-effect separation chamber 242 respectively; the exhaust end of the first-effect separation chamber 222 is connected to the service side air inlet of the second-effect heater 231, the exhaust end of the second-effect separation chamber 232 is connected to the service side air inlet of the triple-effect heater 241, and the exhaust end of the triple-effect separation chamber 242 is connected to the absorption tower 6.

[0077] In this embodiment, the heat source of the first-effect heater 221 is the high-temperature steam delivered from the service-side steam inlet 4, while the heat sources of the second-effect heater 231 and the third-effect heater 241 are the secondary steam separated from the first-effect separation chamber 222 and the second-effect separation chamber 232, respectively.

[0078] Further implementation examples include Figure 1-2 As shown, the first-effect evaporation concentrator 22, the second-effect evaporation concentrator 23 and the third-effect evaporation concentrator 24 are all forced circulation evaporation structures.

[0079] The forced circulation evaporation structure in this embodiment is an existing structure, and the function of forced circulation or liquid discharge is achieved through the cooperation of the circulation pipeline and the valve body.

[0080] Further implementation examples include Figure 1-2 As shown, a condenser 17 is provided between the exhaust end of the three-effect separation chamber 242 and the absorption tower 6, and a condensate upper water inlet 18 and a condensate lower water inlet 19 are provided on the service side of the condenser 17. A wastewater collecting tank 20 is connected to the discharge end of the condenser 17, and a wastewater discharge pipe 21 is provided on the wastewater collecting tank 20; the wastewater collecting tank 20 is connected to the service side discharge ports of the two-effect heater 231 and the three-effect heater 241.

[0081] The wastewater collection tank 20 in this embodiment is mainly used to collect condensed water after cooling of the steam heat source in the second-effect heater 231 and the third-effect heater 241, as well as condensed water after secondary steam condensation discharged from the third-effect separation chamber 242, to avoid pollution caused by condensed water discharge.

[0082] The technical terms "stripping tower", "absorption tower", "vacuum system", "filter press", "preheater", "condenser", "wastewater collection tank", "heater" and "separation chamber" that appear in the embodiments of the present invention are all customary terms in the field. Unless otherwise specified, the equipment referred to by the above terms are all commonly used equipment in the field.

[0083] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A process for concentrating and defluorinating waste sulfuric acid from nickel-cobalt smelting, characterized in that: The steps include: S1. introducing waste sulfuric acid into a preheating system to preheat waste sulfuric acid; S2. The preheated waste sulfuric acid is introduced into the evaporation concentration system for circulation concentration until a fluorine-containing chlorine-containing concentrated sulfuric acid having a sulfuric acid concentration of 70-75% is obtained; S3. The fluorine-containing chlorine-containing concentrated sulfuric acid is introduced into the top of the desorption tower and sprayed down, and the hot air at a temperature of 130-150 ° C is blown and absorbed through the bottom, and the concentrated sulfuric acid is discharged from the bottom; S4. The hot air that absorbs fluorine and chlorine is discharged from the top of the desorption tower and then introduced into the absorption tower, and calcium hydroxide solution is sprayed from the top of the absorption tower. The air after absorption is directly discharged, and the solid-liquid mixture below is separated by solid-liquid separation to obtain calcium fluoride solid and calcium chloride solution.

2. The process for concentrating and defluorinating chlorine from waste sulfuric acid from nickel and cobalt smelting according to claim 1, characterized in that: The heat source of the preheating system is low-temperature steam discharged from the service side of the evaporation concentration system and / or concentrated sulfuric acid discharged from the stripping tower.

3. The process for concentrating and defluorinating chlorine from waste sulfuric acid from nickel and cobalt smelting according to claim 1, characterized in that: The secondary steam generated by the evaporation and concentration system is introduced into the absorption tower together with the hot air discharged from the desorption tower after condensation treatment.

4. The process for concentrating and defluorinating chlorine from waste sulfuric acid from nickel and cobalt smelting according to claim 1, characterized in that: The hot air is dry hot air.

5. A system for concentrating and defluorinating waste sulfuric acid from nickel and cobalt smelting, characterized by: The invention comprises a waste sulfuric acid inlet (1), the waste sulfuric acid inlet (1) is connected to a preheating system (2), the preheating system (2) is connected to an evaporation concentration system (3), the evaporation concentration system (3) is connected to a desorption tower (5), the desorption tower (5) is connected to an absorption tower (6), and the absorption tower (6) is connected to a vacuum system (7); The evaporation and concentration system (3) is provided with a service side steam inlet (4), the liquid inlet end of the evaporation and concentration system (3) is connected to the liquid outlet end of the preheating system (2), and the liquid outlet end of the evaporation and concentration system (3) is connected to the liquid inlet end of the desorption tower (5); The bottom of the stripping tower (5) is connected to a concentrated sulfuric acid outlet (13) and a hot air inlet (25), and the top of the stripping tower (5) is connected to the absorption tower (6); The top of the absorption tower (6) is connected to a sodium hydroxide solution inlet (8) and an air outlet (9), and the bottom is connected to a filter press (10). The filter press (10) is provided with a calcium fluoride extraction outlet (11) and a calcium chloride solution outlet (12).

6. The system for concentrating and defluorinating chlorine from waste sulfuric acid from nickel and cobalt smelting according to claim 5, characterized in that: The preheating system (2) is composed of a primary preheater (14) and a secondary preheater (15) connected in series; wherein the service side liquid inlet of the primary preheater (14) is connected to the liquid discharge port of the stripping tower (5), and the concentrated sulfuric acid discharge port (13) is connected to the service side liquid outlet of the primary preheater (14); the service side air inlet of the secondary preheater (15) is connected to the low-temperature steam discharge port of the evaporation and concentration system (3), and the service side air outlet of the secondary preheater (15) is connected to the condensed water discharge port (16).

7. The system for concentrating and defluorinating chlorine from waste sulfuric acid from nickel and cobalt smelting according to claim 5, characterized in that: The evaporation and concentration system (3) is composed of a first-effect evaporation and concentrator (22), a second-effect evaporation and concentrator (23) and a third-effect evaporation and concentrator (24) connected in series.

8. The system for concentrating and defluorinating chlorine from waste sulfuric acid from nickel and cobalt smelting according to claim 7, characterized in that: The first-effect evaporation concentrator (22) comprises a first-effect heater (221) and a first-effect separation chamber (222); the second-effect evaporation concentrator (23) comprises a second-effect heater (231) and a second-effect separation chamber (232); the third-effect evaporation concentrator (24) comprises a third-effect heater (241) and a third-effect separation chamber (242); the exhaust end of the first-effect separation chamber (222) is connected to the service-side air inlet of the second-effect heater (231), the exhaust end of the second-effect separation chamber (232) is connected to the service-side air inlet of the third-effect heater (241), and the exhaust end of the third-effect separation chamber (242) is connected to an absorption tower (6).

9. The system for concentrating and defluorinating chlorine from waste sulfuric acid from nickel and cobalt smelting according to claim 8, characterized in that: The first-effect evaporation concentrator (22), the second-effect evaporation concentrator (23) and the third-effect evaporation concentrator (24) are all forced circulation evaporation structures.

10. The system for concentrating and defluorinating chlorine from waste sulfuric acid from nickel and cobalt smelting according to claim 8, characterized in that: A condenser (17) is provided between the exhaust end of the three-effect separation chamber (242) and the absorption tower (6); a condensate upper inlet (18) and a condensate lower inlet (19) are provided on the service side of the condenser (17); a wastewater collection tank (20) is connected to the discharge end of the condenser (17); and a wastewater discharge pipe (21) is provided on the wastewater collection tank (20); the wastewater collection tank (20) is connected to the service side discharge ports of the two-effect heater (231) and the three-effect heater (241).

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