Chlorine recovery method for chlorination electrodeposition nickel production

Abstract

The invention provides a chlorine gas recovery method for production of chlorinated electrodeposited nickel, belongs to the technical field of hydrometallurgy, solves the problem of poor chlorine gas recovery effect in the production process of chlorinated electrodeposited nickel, and comprises a gas collection device which is sequentially connected with a gas-liquid separator, a multi-stage cooler, a drying tower and a chlorine gas compressor, the chlorine gas compressor is respectively connected with a chlorine gas leaching device and an accident emergency treatment tank; wet chlorine and anolyte enter a gas collection device and then enter a gas-liquid separator; wet chlorine is subjected to water removal, impurity removal and drying through a multi-stage cooler and a drying tower, is compressed by a chlorine compressor, and enters a chlorine leaching device when the chlorine concentration meets the requirement; and the chlorine enters the accident emergency disposal tank when the chlorine concentration does not meet the requirement. The chlorine can be completely recycled, the unit processing cost is obviously reduced, the discharge amount of tail gas and sewage is greatly reduced, the working environment is improved, and the refining technology of the chlorinated electrodeposited nickel is further perfected.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a chlorine recovery method for nickel chloride electrodeposition production. Background Art

[0002] Nickel chloride production technology is a domestic first, and nickel chloride is a domestic first product. Nickel chloride is a high-purity nickel chloride solution that utilizes a chlorination system. After an electrolytic process, metal ions are precipitated on the cathode, and chloride ions are precipitated on the anode to release chlorine gas. This process has the characteristics of short process, low cost and excellent product quality.

[0003] Judging from the current production situation of nickel chloride electrowinning, the recovery and utilization of chlorine generated in the anode process is the core technology in the production process of nickel chloride electrowinning. At present, the production of nickel chloride electrowinning has the following problems: the recovery and utilization effect of chlorine is not good, there is a lack of recovery technology, chlorine is easy to escape from the liquid surface of the electrolytic cell and enter the air to cause on-site environmental pollution; there is a lack of low-concentration chlorine utilization technology, and there is no mature recovery and utilization technology to learn from in China. Therefore, it is necessary to invent a recovery and utilization system for chlorine generated in the production process of chloride electrowinning to solve the problems of recovery and utilization. Summary of the invention

[0004] The purpose of the present invention is to provide a chlorine recovery method for nickel chloride electrowinning production, so as to solve the problem of poor chlorine recovery and utilization effect in the nickel chloride electrowinning production process.

[0005] The technical solution of the present invention is: a chlorine recovery method for nickel electrolytic production by chloride, the device structure used is as follows, including a gas collecting device, the gas collecting device is sequentially connected to a gas-liquid separator, a multi-stage cooler, a drying tower and a chlorine compressor, the chlorine compressor is respectively connected to a chlorine leaching device and an accident emergency disposal tank; The method comprises the following steps: Step 1: The wet chlorine gas and the anolyte enter the gas collecting device to collect the chlorine gas, and then enter the gas-liquid separator to separate the wet chlorine gas and the anolyte, and the anolyte returns to the production system for reuse; Step 2: The wet chlorine gas separated by the gas-liquid separator passes through a multi-stage cooler and a drying tower to remove water, impurities and dry the wet chlorine gas; Step 3: After the dried chlorine is compressed by the chlorine compressor, it enters the chlorine leaching device for further recycling when the chlorine concentration reaches the requirement; when the chlorine concentration does not meet the requirement, it enters the accident emergency disposal tank for treatment and then meets the discharge standards.

[0006] As a further improvement of the present invention, the gas collecting device includes an electrolytic cell, in which an insoluble anode is suspended by a conductive rod, an anode bag is provided on the insoluble anode, an anode cover is provided on the upper part of the insoluble anode, and the electrolytic cell is also provided with an exhaust pipe, a liquid exhaust pipe and a tank side gas collecting pipe.

[0007] As a further improvement of the present invention, the chlorine compressor is connected to the chlorine leaching device and the accident emergency disposal tank respectively through the chlorine pressure stabilizing tank.

[0008] As a further improvement of the present invention, the multi-stage cooler includes a primary cooler and a secondary cooler. The primary cooler is connected to a circulating water machine and is also provided with a chilled water unit, which flows into the secondary cooler.

[0009] As a further improvement of the present invention, an automatically controlled vacuum regulating loop is provided in the chlorine compressor.

[0010] As a further improvement of the present invention, in step 2, the multi-stage cooler includes a primary cooler and a secondary cooler, and the temperature of the wet chlorine gas in the secondary cooler is reduced to below 15°C.

[0011] As a further improvement of the present invention, in step 2, 98% concentrated sulfuric acid is introduced into the drying tower.

[0012] As a further improvement of the present invention, in step three, the inlet vacuum degree of the chlorine compressor is -0.02 to -0.05 MPa, and the outlet pressure of the chlorine compressor is 0.35 to 0.45 MPa.

[0013] As a further improvement of the present invention, in step three, when the chlorine concentration is lower than 50%, it enters the accident emergency disposal tank.

[0014] The beneficial effects of the present invention are as follows: chlorine gas and anode liquid enter a gas collecting device to effectively collect chlorine gas, and then pass through a gas-liquid separator for gas-liquid separation. After the chlorine gas is cooled by a multi-stage cooler, most of the saturated water and entrained matter can be removed, and then the chlorine gas is dried by concentrated sulfuric acid in a drying tower. If the dried chlorine gas meets the concentration requirement, it can be sent to a chlorine leaching device for leaching copper slag and raw materials, and the leachate composition meets the production requirement; if the chlorine concentration is low and does not meet the concentration requirement, the chlorine gas cannot enter the chlorine leaching device, but is discharged into a chlorine accident emergency disposal tank, and is discharged after a neutralization reaction with sodium hydroxide meets the standard.

[0015] The gas collecting device is designed in a specific way: the insoluble anode is suspended in the electrolytic cell by a conductive rod, which mainly plays the role of conductivity. It can transmit current and ensure the stable transmission of current during the electrolysis process, thereby ensuring the normal progress of the electrolysis reaction, so that the insoluble anode can effectively precipitate metal ions during the electrolysis process, help maintain the balance of the electrolyte, and thus ensure the stability and efficiency of the production process; the main function of the anode bag on the insoluble anode is to form a gas collecting cavity with the anode cover on the upper part of the insoluble anode, effectively preventing the escape of chlorine and improving the recovery effect of chlorine; the exhaust pipe, liquid extraction pipe and tank side gas collecting pipe are arranged on the electrolytic cell to ensure the effective collection of gas, stabilize the gas flow and optimize the gas distribution.

[0016] In order to stabilize the tank surface liquid level, prevent air from entering the chlorine system, improve the purity of chlorine, and facilitate the recovery and reuse of chlorine, a vacuum adjustment loop is added to the chlorine compressor, and automatic control technology is used to ensure the stability and adjustability of the system vacuum. Finally, the chlorine concentration is selected to enter the chlorine leaching device or the accident emergency disposal tank, providing follow-up treatment options for different situations, increasing the effective recovery and utilization of chlorine, so that the chlorine in the nickel electrowinning process is effectively recovered and utilized, reducing production costs and environmental pollution.

[0017] The present invention aims at the process of producing nickel electrolytic chloride. After the mixture of chlorine gas and anolyte is passed through the processes of electrolytic gas collection device, gas-liquid separation, multi-stage cooling, drying, compression, chlorine gas leaching or accident emergency disposal tank, the chlorine gas can be completely recovered and utilized, the unit processing cost is significantly reduced, the exhaust gas and sewage discharge are greatly reduced, the working environment is improved, the nickel electrolytic chloride refining technology is further improved, the nickel electrolytic chloride refining technology has obvious economic and social benefits, and the nickel electrolytic chloride production process technology is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a connection structure diagram of the system of the present invention; Figure 2 This is a structural diagram of the gas collecting device in the present invention.

[0019] In the figure: 1-gas collecting device; 2-gas-liquid separator; 3-primary cooler; 4-secondary cooler; 5-drying tower; 6-chlorine compressor; 7-chlorine pressure regulating tank; 8-chlorine leaching device; 9-accident emergency disposal tank; 10-circulating water machine; 11-chilled water unit; 12-electrodeposition tank; 13-insoluble anode; 14-anode bag; 15-anode cover; 16-exhaust pipe; 17-liquid extraction pipe; 18-tank side gas collecting pipe; 19-conductive rod. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] like Figure 1-Figure 2 As shown, a chlorine recovery method for nickel electrolytic production using chloride, the device structure used is as follows, including a gas collecting device 1, the gas collecting device 1 is sequentially connected to a gas-liquid separator 2, a multi-stage cooler, a drying tower 5 and a chlorine compressor 6, the chlorine compressor 6 is respectively connected to a chlorine leaching device 8 and an accident emergency disposal tank 9; The method comprises the following steps: Step 1: wet chlorine gas and anolyte enter the gas collecting device 1 to collect chlorine gas, and then enter the gas-liquid separator 2 to separate the wet chlorine gas and anolyte, and the anolyte returns to the production system for reuse; Step 2: The wet chlorine gas separated by the gas-liquid separator 2 passes through a multi-stage cooler and a drying tower 5 to remove water, impurities and dry the wet chlorine gas; Step 3: After the dried chlorine is compressed by the chlorine compressor 6, it enters the chlorine leaching device 8 for further recycling when the chlorine concentration reaches the requirement; when the chlorine concentration does not reach the requirement, it enters the accident emergency disposal tank 9 for treatment and then meets the discharge standards.

[0022] The gas collecting device 1 comprises an electrolytic cell 12, in which an insoluble anode 13 is suspended by a conductive rod 19, an anode bag 14 is provided on the insoluble anode 13, an anode cover 15 is provided on the upper part of the insoluble anode 13, and the electrolytic cell 12 is also provided with an exhaust pipe 16, a liquid exhaust pipe 17 and a tank side gas collecting pipe 18.

[0023] The chlorine compressor 6 is connected to the chlorine extraction device 8 and the accident emergency disposal tank 9 through the chlorine pressure stabilizing tank 7. The multi-stage cooler includes a primary cooler 3 and a secondary cooler 4. The primary cooler 3 is connected to a circulating water machine 10 and is also provided with a chilled water unit 11, which is connected to the secondary cooler 4. The chlorine compressor 6 is provided with an automatically controlled vacuum regulating circuit.

[0024] In step 2, the multi-stage cooler includes a primary cooler 3 and a secondary cooler 4, and the temperature of the wet chlorine in the secondary cooler 4 drops to below 15°C. In step 2, 98% concentrated sulfuric acid is introduced into the drying tower 5. In step 3, the inlet vacuum degree of the chlorine compressor 6 is -0.02 to -0.05Mpa, and the outlet pressure of the chlorine compressor 6 is 0.35 to 0.45Mpa. In step 3, when the chlorine concentration is less than 50%, it enters the accident emergency disposal tank 9.

[0025] Embodiment 1, The mixture of wet chlorine and anode liquid enters the gas collecting device 1 for gas collection, and then enters the gas-liquid separator 2 through the air extraction pipe 16, the liquid extraction pipe 17, and the tank side gas collection pipe 18 in sequence. The gas collecting device 1 is mainly used to collect the wet chlorine generated in the production process to ensure that it will not escape into the environment, thereby reducing environmental pollution; in the process of wet chlorine recovery, the vacuum generated at the compressor inlet can prevent the occurrence of backflow and ensure that the liquid will not flow back into the system.

[0026] The mixture of wet chlorine and anolyte enters the gas-liquid separator 2, and the anolyte is discharged from the lower drain pipe by gravity. The wet chlorine is discharged from the top of the gas-liquid separator 2 and enters the primary cooler 3. The primary cooler 3 is a tube-in-tube cooler. The wet chlorine introduced into the tube enters from the bottom and exits from the top. After cooling, it enters the secondary cooler 4. The temperature of the chlorine after cooling in the primary cooler 3 is less than 30°C. The shell of the primary cooler 3 contains circulating cooling water introduced by the circulating water machine 10. The primary cooler 3 is provided with a temperature detection and adjustment device, which can realize the detection and automatic adjustment of the temperature of the titanium tube cooler. The wet chlorine after cooling in the primary cooler 3 enters the secondary cooler 4. The wet chlorine introduced into the secondary cooler 4 enters from the bottom and exits from the top. The shell of the secondary cooler 4 contains chilled water provided by the chiller 11. The temperature of the wet chlorine is reduced to below 15°C by the secondary cooler 4, thereby removing more than 90% of the saturated water and entrained materials.

[0027] The circulating water from the primary cooler 3 and the refrigerated circulating water from the secondary cooler 4 can be reused, increasing the recycling rate of resources. The main reason for setting up a multi-stage cooler is to improve cooling efficiency, enhance system flexibility, adapt to different environmental conditions, improve system reliability, and minimize energy consumption.

[0028] The wet chlorine gas cooled by the secondary cooler 4 enters from the side of the drying tower 5 and flows upward. The drying tower 5 is fed with concentrated sulfuric acid with a concentration of 98% as a desiccant. The concentrated sulfuric acid of 98% has the characteristics of being difficult to dilute, maintaining acidity and oxidizability, and being able to continuously dry the wet chlorine gas. The concentrated sulfuric acid of 98% is sprayed downward from the top of the drying tower 5 in a mist-like manner and is countercurrent dried. The water content of the gas entering the drying tower 5 is 0.4%, and the water content of the dried chlorine gas is less than 0.05%. The extremely low water content of the dried chlorine gas can facilitate the selection of chlorine gas compression, storage equipment and conveying pipeline materials, and has high economy. The concentration of the concentrated sulfuric acid after use after entering the drying tower 5 drops to below 93%, and the water absorption and oxidizability change, so it can no longer be used for drying gas, and can be used as recycling to achieve repeated use. Concentrated sulfuric acid flows back to the sulfuric acid circulation tank from the bottom of the drying tower 5, and dry chlorine is discharged from the top of the drying tower 5 from bottom to top and enters the chlorine compressor 6. A pressure sensor and a temperature sensor are installed at the outlet of the chlorine pipeline at the top of the drying tower 5, which can realize the detection of the pressure and temperature of the chlorine at the outlet of the drying tower 5.

[0029] In order to stabilize the tank surface liquid level, prevent air from entering the chlorine system, improve the purity of chlorine, and facilitate the recovery and reuse of chlorine, a vacuum regulating loop is added to the chlorine compressor 6, and automatic control technology is adopted to ensure the stability and adjustability of the system vacuum degree. The inlet vacuum degree of the chlorine compressor 6 is -0.02~-0.05Mpa, and the outlet pressure of the chlorine compressor 6 is 0.35~0.45Mpa; a reflux pipeline is set on the outlet pipeline of the chlorine compressor 6, connected to the inlet pipeline of the chlorine compressor 6, and a vacuum meter is installed on the connecting pipeline of the outlet pipeline of the chlorine compressor 6 and the inlet pipeline, and an automatic regulating valve is installed on the connecting pipeline. The valve is interlocked with the vacuum meter to balance the system vacuum degree by adjusting the valve opening size, so as to realize the detection and automatic adjustment of the inlet and outlet pressures of the chlorine compressor 6. The chlorine compressor 6 passes the compressed chlorine into the chlorine pressure regulating tank 7. The chlorine pressure regulating tank 7 can maintain the system pressure stability and adjust the chlorine flow rate to ensure the stable operation and safe supply of the system. The inlet pipe of the chlorine compressor 6 to the anode cover 15 of the electrolytic cell 12 is welded, which further prevents air from entering the vacuum pipe.

[0030] When the chlorine concentration is greater than 50%, the compressed dry chlorine enters the chlorine leaching device 8, and copper-nickel concentrate slurry is quantitatively added to the chlorine leaching device 8 to strictly control the leaching potential to achieve the purification of valuable metals such as nickel, copper and cobalt. By recycling the chlorine generated during the electrolytic process of this system and using chlorine to leach copper slag and nickel concentrate, not only the consumption of sodium hydroxide absorption liquid is reduced, but also the supply of fresh chlorine from external plants is saved, thereby achieving great economic benefits.

[0031] Once an accident occurs or the chlorine concentration is low, that is, when the chlorine concentration is lower than 50%, the chlorine cannot enter the chlorine leaching device, and the chlorine is discharged into the accident emergency disposal tank 9 and reacts with sodium hydroxide to meet the standard before being discharged. The automatic regulating valve leading from the chlorine compressor 6 to the accident emergency disposal tank 9 is interlocked with the chlorine concentration detection device on the chlorine compressor 6 to achieve the interlocking control of chlorine compression 6 and the accident emergency disposal tank 9. When the pressure in the chlorine main pipe suddenly changes and chlorine may leak, the automatic regulating valve leading to the accident emergency disposal tank 9 is automatically opened immediately to send the chlorine to the accident emergency disposal tank 9 and be discharged after being absorbed by alkali solution and meeting the standard.

Claims

1. A chlorine recovery method for nickel chloride electrowinning production, characterized in that: The structure of the device used is as follows, comprising a gas collecting device (1), wherein the gas collecting device (1) is sequentially connected to a gas-liquid separator (2), a multi-stage cooler, a drying tower (5) and a chlorine compressor (6), and the chlorine compressor (6) is respectively connected to a chlorine leaching device (8) and an accident emergency disposal tank (9); The method comprises the following steps: Step 1: The wet chlorine gas and the anolyte enter the gas collecting device (1) to collect the chlorine gas, and then enter the gas-liquid separator (2) to separate the wet chlorine gas and the anolyte, and the anolyte is returned to the production system for reuse; Step 2: the wet chlorine gas separated by the gas-liquid separator (2) passes through a multi-stage cooler and a drying tower (5) to remove water, impurities and dry the wet chlorine gas; Step 3: The dried chlorine gas is compressed by the chlorine compressor (6) and enters the chlorine leaching device (8) for further recycling when the chlorine concentration reaches the required level; if the chlorine concentration does not reach the required level, it enters the accident emergency disposal tank (9) for treatment and then meets the discharge standards.

2. The chlorine recovery method for nickel chloride electrowinning production according to claim 1, characterized in that: The gas collecting device (1) comprises an electrolytic cell (12), in which an insoluble anode (13) is suspended via a conductive rod (19), an anode bag (14) is provided on the insoluble anode (13), an anode cover (15) is provided on the upper part of the insoluble anode (13), and the electrolytic cell (12) is also provided with an air extraction pipe (16), a liquid extraction pipe (17) and a cell-side gas collecting pipe (18).

3. A chlorine recovery method for nickel chloride electrowinning production according to claim 1 or 2, characterized in that: The chlorine compressor (6) is connected to the chlorine leaching device (8) and the accident emergency disposal tank (9) respectively through the chlorine pressure stabilizing tank (7).

4. A chlorine recovery method for nickel chloride electrowinning production according to claim 3, characterized in that: The multi-stage cooler comprises a primary cooler (3) and a secondary cooler (4); the primary cooler (3) is connected to a circulating water machine (10) and is also provided with a chilled water unit (11); the chilled water unit (11) is connected to the secondary cooler (4).

5. A chlorine recovery method for nickel chloride electrowinning production according to claim 4, characterized in that: The chlorine compressor (6) is provided with an automatically controlled vacuum regulating circuit.

6. A chlorine recovery method for nickel chloride electrowinning production according to claim 1, characterized in that: In step 2, the multi-stage cooler includes a primary cooler (3) and a secondary cooler (4), and the temperature of the wet chlorine gas in the secondary cooler (4) is reduced to below 15°C.

7. A chlorine recovery method for nickel chloride electrowinning production according to claim 1, characterized in that: In step 2, 98% concentrated sulfuric acid is introduced into the drying tower (5).

8. A chlorine recovery method for nickel chloride electrowinning production according to claim 1, characterized in that: In step 3, the inlet vacuum degree of the chlorine compressor (6) is -0.02 to -0.05 MPa, and the outlet pressure of the chlorine compressor (6) is 0.35 to 0.45 MPa.

9. A chlorine recovery method for nickel chloride electrowinning production according to claim 1, characterized in that: In step 3, when the chlorine concentration is lower than 50%, it enters the accident emergency disposal tank (9).

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