Electrolytic device for lead-zinc smelting high-chlorine sodium sulfate wastewater and electrolytic method thereof

Abstract

The application belongs to the technical field of water treatment, and particularly discloses a lead-zinc smelting high-chloride sodium sulfate wastewater electrolysis device and an electrolysis method thereof. The device is characterized in that an anion membrane is arranged in the middle of a cation membrane electrolytic cell, and anode and cathode chambers are arranged on both sides of the membrane; the anode and cathode chambers are respectively connected with an anode and a cathode of a power supply; the anode chamber of the cation membrane electrolytic cell is connected with a brine circulation tank through inlet and outlet ports, the cathode chamber is connected through a circulation pipe, and the gas outlets of the anode and cathode chambers are respectively connected with a chlorine gas collecting and processing device and a hydrogen gas collecting or processing device; the cathode chamber of the anion membrane electrolytic cell is connected with the brine circulation tank through inlet and outlet ports, the anode chamber is connected through a circulation pipe, and the gas outlets of the anode and cathode chambers are respectively connected with the chlorine gas collecting and processing device and the hydrogen gas collecting or processing device. The method comprises the steps of pretreatment, coupled electrolysis and post-treatment. The application has the characteristics of compact structure, simple process, high electrolysis efficiency, high product purity and efficient and synergistic removal of chlorides in lead-zinc wastewater.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of water treatment, in particular to a lead-zinc smelting high-chloride sodium sulfate wastewater electrolysis device and an electrolysis method thereof, which are compact in structure, simple in process, high in electrolysis efficiency, high in product purity and efficient in synergistic removal of chlorides in lead-zinc wastewater. BACKGROUND

[0002] The wastewater of lead-zinc smelting enterprises not only has a large output, but also has complex components. After a series of process treatments, the wastewater is finally reused or discharged. At present, the Discharge Standard of Pollutants in Lead and Zinc Industry (GB 25466-2010) and the modification thereof have discharge limits for pH, chemical oxygen demand, suspended solids, fluorides, heavy metals and the like, but do not give limits for chlorides and sodium ions. In addition, the Reuse of Urban Recycling Water - Water Quality for Industrial Use (GB 19923-2005) and the Water Quality Standard for Urban Domestic Miscellaneous Water Use (GB / T 18920-2020) do not have requirements for sodium ions in the reused water, so that the reused or discharged water after the treatment of the lead-zinc smelting wastewater is high-salt wastewater, mainly containing SO4 2- , Na + , Cl - , calcium, magnesium, heavy metals and the like. The reuse of the lead-zinc smelting wastewater in production will cause the enrichment of sodium ions and chloride ions in the production system, affecting the production, and the direct discharge will cause the waste of the resources rich therein and the increase of the soil salinization and the water mineralization, thus endangering the ecological environment.

[0003] The traditional lead-zinc smelting high-salt wastewater treatment method has a thermal method (evaporation) and a membrane method, wherein the membrane method has reverse osmosis, microfiltration, ultrafiltration, sodium filtration and electrodialysis. However, the traditional treatment method has problems of a long treatment cycle, high cost, difficult recovery of sodium sulfate or poor economic benefits and the like. In recent years, more researches on the electrolysis of sodium sulfate to produce acid and alkali have been carried out at home and abroad, and new progress has been made. However, the single-membrane electrolysis technology can only electrolyze sodium sulfate into NaOH and H2SO4-Na2SO4 mixed solution or H2SO4 and NaOH-Na2SO4 mixed solution, cannot completely obtain acid and alkali products, and the concentration of H + in the H2SO4-Na2SO4 mixed solution will affect the selective permeability of the membrane to Na + , thus affecting the electrolysis result. In the process of electrolyzing Na2SO4 to NaOH and H2SO4 by using an anion membrane and a cation membrane, it is difficult to effectively control the interelectrode distance (the smaller the interelectrode distance, the higher the electrolysis efficiency), and the ion membrane has a poor blocking effect on H + , so that the salt chamber is in the H2SO4-Na2SO4 system, thus significantly reducing the acid electrolysis efficiency.

[0004] In the prior art, patent CN218539382U discloses an industrial sodium sulfate wastewater electrolysis device, which is compared with conventional electrolytic cell electrolysis, and an adjustable electrode is arranged in the two-chamber electrolytic cell, and the inter-electrode distance can be freely adjusted during electrolysis, and a stirring paddle device is arranged in the electrolytic cell. Although the device realizes the adjustment of the electrode spacing, since it still adopts a membrane two-chamber electrolysis structure, there are problems of low acid current efficiency and inability to completely obtain acid and alkali products. Patent CN103060834B discloses a process flow for continuous electrolysis of industrial sodium sulfate wastewater, which requires that the sodium sulfate raw material be filtered to remove impurities SS < 50 mg / L, and harmful ions Ca 2+ +Mg 2+ < 20 ppb, and the pretreated sodium sulfate is electrolyzed by using a cation membrane electrolytic cell; however, the pretreatment requirement of the process is high, and the anode chamber system is H2SO4-Na2SO4, which cannot completely separate H2SO4. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application provides a lead-zinc smelting high-chlorine sodium sulfate wastewater electrolysis device with compact structure, simple process, high electrolysis efficiency, high product purity and efficient synergistic removal of chlorides in lead-zinc wastewater, and a lead-zinc smelting high-chlorine sodium sulfate wastewater electrolysis method.

[0006] The lead-zinc smelting high-chlorine sodium sulfate wastewater electrolysis device is implemented as follows: a cation membrane electrolytic cell, a salt liquid circulating tank, an anion membrane electrolytic cell and a power supply are provided, the cation membrane electrolytic cell and the anion membrane electrolytic cell are each provided with a cathode chamber and an anode chamber on both sides of an ion membrane, the cathode chamber and the anode chamber are each a frame-shaped structure with one end open and are each provided with a liquid inlet, a liquid outlet and a gas outlet penetrating the inside and outside of the side wall, the cathode chamber is provided with a cathode with adjustable spacing, the anode chamber is provided with an anode with adjustable spacing, and the cathode and the anode are each electrically connected to a power output port of the power supply.

[0007] The cathode chamber and the anode chamber of the cation membrane electrolytic cell are in parallel and airtight butt joint with the openings opposite to each other, and a cation exchange membrane is arranged between the cathode chamber and the anode chamber, the liquid inlet and the liquid outlet of the anode chamber of the cation membrane electrolytic cell are respectively communicated with the salt liquid circulating tank, the liquid inlet and the liquid outlet of the cathode chamber of the cation membrane electrolytic cell are communicated through an external circulating pipe, a circulating pump and a three-way valve are connected in series on the circulating pipe, one port of the three-way valve is communicated with a product alkali storage tank, the gas outlet of the anode chamber of the cation membrane electrolytic cell is communicated with a chlorine gas collection and treatment device, and the gas outlet of the cathode chamber is communicated with a hydrogen gas collection or treatment device.

[0008] The anion membrane electrolytic cell and the cation membrane electrolytic cell have the same structure, and an anion exchange membrane is arranged between a cathode chamber and an anode chamber, liquid inlet and liquid outlet of the cathode chamber of the anion membrane electrolytic cell are communicated with a salt liquid circulating tank, liquid inlet and liquid outlet of the anode chamber of the anion membrane electrolytic cell are communicated through an external circulating pipe, a circulating pump and a three-way valve are connected in series on the circulating pipe, one port of the three-way valve is communicated with a product acid storage tank, a gas outlet of the anode chamber of the anion membrane electrolytic cell is communicated with a chlorine gas collecting and processing device, and a gas outlet of the cathode chamber is communicated with a hydrogen gas collecting and processing device.

[0009] Further, the anode of the cation membrane electrolytic cell and the anode of the anion membrane electrolytic cell are respectively a titanium mesh or a titanium plate with a ruthenium iridium or iridium tantalum oxide coating, and the cathode is a titanium mesh or a titanium plate, and the distance between the anode and the cathode is 1-4 cm.

[0010] Further, the chlorine gas collecting and processing device is a chlorine gas detoxification device, the gas inlet of the chlorine gas detoxification device is communicated with the gas outlet of the anode chamber of the cation membrane electrolytic cell and the anode chamber of the anion membrane electrolytic cell, and the feed inlet of the chlorine gas detoxification device is communicated with the three-way valve connected in series on the external circulating pipe of the cathode chamber of the cation membrane electrolytic cell.

[0011] Further, the bottom end of the cathode chamber and the anode chamber away from the gas outlet is provided with an electrode power supply port, and the cathode and the anode are respectively fixedly provided with an electrode power supply handle which can move through the electrode power supply port to adjust the position of the electrode, and the electrode power supply handle is electrically connected with the power supply output port of the power supply.

[0012] Further, a plurality of threaded holes are respectively arranged on the side walls of the cathode chamber and the anode chamber, the cathode chamber and the anode chamber are fixedly connected through screws penetrating the threaded holes, the cation exchange membrane or the anion exchange membrane is fixedly arranged between the open end faces of the cathode chamber and the anode chamber, and airtight silica gel pads are arranged between the open end faces of the cathode chamber and the anode chamber.

[0013] The lead-zinc smelting high-chlorine sodium sulfate wastewater electrolysis method is realized by the following steps: pretreatment, coupled electrolysis and post-treatment.

[0014] A, pretreatment: the lead-zinc smelting high-chlorine sodium sulfate wastewater is mixed with alkali or alkali obtained in the coupled electrolysis step, then impurities are removed by suction filtration, and high-salt wastewater containing chlorine is obtained;

[0015] B, coupling electrolysis: the high salt wastewater containing chlorine is introduced into the salt solution circulating tank, and then the high salt wastewater containing chlorine in the salt solution circulating tank is continuously circulated and electrolyzed in the anode chamber of the cation membrane electrolytic tank and the cathode chamber of the anion membrane electrolytic tank respectively through the circulating pump, and at the same time, the cathode liquid in the cathode chamber of the cation membrane electrolytic tank and the anode liquid in the anode chamber of the anion membrane electrolytic tank are continuously circulated through the circulating pump, when the alkali concentration in the cathode liquid in the cathode chamber of the cation membrane electrolytic tank reaches the preset concentration, the cathode liquid is discharged to the product alkali storage tank through the three-way valve, and when the acid concentration in the anode liquid in the anode chamber of the anion membrane electrolytic tank reaches the preset concentration, the anode liquid is discharged to the product acid storage tank through the three-way valve;

[0016] C, post-treatment: collecting hydrogen gas discharged from the cathode chamber outlet of the cation membrane electrolytic tank, and introducing chlorine gas and oxygen gas discharged from the anode chamber outlet of the cation membrane electrolytic tank and the anode chamber outlet of the anion membrane electrolytic tank into the chlorine gas collection and treatment device storing the alkali diluent, absorbing the toxic chlorine gas, and discharging clean oxygen gas.

[0017] Further, in the pretreatment step, the SS of the high salt wastewater containing chlorine after removing impurities is less than 50 mg / L, the pH is greater than or equal to 9.8, and the sodium sulfate concentration is greater than 0.35 mol / L; in the coupling electrolysis step, the sum of the volumes of the salt solutions in the salt solution circulating tank, the anode chamber of the cation membrane electrolytic tank and the cathode chamber of the anion membrane electrolytic tank is at least 1.5 times the sum of the volumes of the anode chamber of the cation membrane electrolytic tank and the cathode chamber of the anion membrane electrolytic tank.

[0018] Further, in the coupling electrolysis step, the current density of electrolysis is 20-100 mA / cm 2 , and the electrolyte in the cathode chamber and the anode chamber is circulated once every 3-5 min; when the suspended substance concentration in the high salt wastewater containing chlorine in the salt solution circulating tank is greater than 100 mg / L or the H + concentration is greater than 1.0 mol / L, the high salt wastewater containing chlorine is pumped to the pretreatment step for treatment.

[0019] Further, in the coupling electrolysis step, the high salt wastewater containing chlorine is continuously circulated and electrolyzed for more than 3 h, and the removal rate of chlorides is 90-95%.

[0020] Further, in the coupling electrolysis step, when the alkali concentration in the cathode liquid in the cathode chamber of the cation membrane electrolytic tank reaches the preset requirement, the cathode liquid is discharged to the product alkali storage tank, and when the acid concentration in the anode liquid in the anode chamber of the anion membrane electrolytic tank reaches the preset requirement, the anode liquid is discharged to the product acid storage tank.

[0021] Further, in the coupling electrolysis, deionized water or 0.5-1% sodium hydroxide solution is introduced into the cathode chamber of the cation membrane electrolytic tank before electrolysis starts, and deionized water or 0.5-1% sulfuric acid solution is introduced into the anode chamber of the anion membrane electrolytic tank before electrolysis starts.

[0022] Further, the alkali diluent in the post-processing step is the cathode liquid containing alkali discharged from the cathode chamber of the cation membrane electrolytic cell, which is diluted to 1.0-1.5% of sodium hydroxide.

[0023] The present application has the following advantages:

[0024] 1. The present application can effectively remove the SO4 2- , Na + , Cl - , calcium, magnesium, heavy metals and other lead and zinc smelting sodium sulfate wastewater, and can efficiently produce reusable high-quality acid and alkali.

[0025] 2. The present application innovatively adopts a coupling electrolytic cell structure of a cation membrane electrolytic cell and an anion membrane electrolytic cell, and sets a shared salt liquid circulating tank, and the high-salt wastewater containing chlorine in the salt liquid circulating tank is pumped into the anode chamber of the cation membrane electrolytic cell and the cathode chamber of the anion membrane electrolytic cell as an electrolyte and is circulated and electrolyzed, under the action of an electric field, the concentration of NaOH in the cathode chamber of the cation membrane electrolytic cell gradually increases, and the concentration of H2SO4 in the anode chamber of the anion membrane electrolytic cell gradually increases, and the high-salt wastewater containing chlorine in the salt liquid circulating tank is pumped to the pretreatment step for treatment to control the H + concentration of the electrolyte circulating in the salt liquid circulating tank in the coupling electrolysis step to be less than or equal to 1.0 mol / L, thereby reducing the influence of the H + concentration in the anode chamber of the cation membrane electrolytic cell on the selective permeability of Na + , and avoiding the formation of a large amount of H2SO4-Na2SO4 system in the cathode chamber of the anion membrane electrolytic cell, thereby ensuring the efficiency of electrolysis, and removing Cl - from the high-salt wastewater containing chlorine to form chlorine gas and discharge, so that high-purity acid and alkali products can be finally prepared for reuse, and the prepared alkali products can be used for pretreatment to remove calcium and magnesium ions in the wastewater, so that the mineralization and Cl - in the finally discharged wastewater are significantly reduced, and the problems of affecting production by reuse and causing soil salinization and water mineralization increase by direct discharge are avoided.

[0026] 3. The electrolysis method of the present invention pre-treats the lead-zinc smelting sodium sulfate wastewater with alkali, mixes it, and removes impurities by suction filtration. Therefore, the pre-treatment process is simple and has low requirements. Then, by adopting an electrolysis device with a coupled electrolytic cell structure, the pre-treated chlorine-containing high-salt wastewater is passed into the electrode chamber on one side of the ion membrane of the coupled electrolytic cell structure through a circulating pump as an electrolyte for circulated electrolysis, and finally NaOH and H2SO4 solutions are produced respectively in the electrode chamber on the other side of the ion membrane of the coupled electrolytic cell structure, thereby ensuring that the produced acid and alkali have high purity. In addition, the continuous circulation electrolysis can also avoid the reduction of the extreme concentration difference of the electrode liquid in the electrode chambers on both sides of the ion membrane of the electrolytic cell, thereby ensuring that the electrolysis process can maintain a high efficiency.

[0027] In summary, the present invention has the characteristics of compact structure, simple process, high electrolysis efficiency, high product purity and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the principle of the lead-zinc smelting sodium sulfate wastewater electrolysis device of the present invention;

[0029] Figure 2 for Figure 1 A top view of

[0030] Figure 3 for Figure 1 Schematic diagram of the three-dimensional structure of the anode chamber;

[0031] Figure 4 This is a flow chart of the electrolysis method of high-chloride sodium sulfate wastewater from lead and zinc smelting according to the present invention;

[0032] In the figure: 1-cationic membrane electrolyzer, 2-salt solution circulation tank, 3-anion membrane electrolyzer, 4-power supply, 5A-anode compartment liquid inlet of cationic membrane electrolyzer, 5-cathode compartment liquid inlet of anion membrane electrolyzer, 6A-anode compartment liquid outlet of cationic membrane electrolyzer, 6-cathode compartment liquid outlet of anion membrane electrolyzer, 7A-anode compartment gas outlet of cationic membrane electrolyzer, 7-cathode compartment gas outlet of anion membrane electrolyzer, 8-cation exchange membrane, 9-circulation pipe A, 10-anion exchange membrane, 11-chlorine detoxification device, 12-electrode power supply port, 13-screw, 14-sealed silicone pad, 15-salt solution circulation pipe, 16-electrode, 17-circulation pump, 18-three-way valve B. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] like Figure 1 、 2The lead-zinc smelting high-chlorine sodium sulfate wastewater electrolysis device of the present application is shown in FIGS. 1-3, and comprises a cation membrane electrolytic cell 1, a salt liquid circulating tank 2, an anion membrane electrolytic cell 3, and a power supply 4. The cation membrane electrolytic cell 1 and the anion membrane electrolytic cell 3 are each provided with a cathode chamber and an anode chamber on both sides of the ion membrane. The cathode chamber and the anode chamber are each in a frame-shaped structure with one end open, and the side walls are each provided with liquid inlet and outlet ports and gas outlet ports that penetrate the inside and outside. The anode chamber is provided with anode with adjustable spacing. The cathode and the anode are each electrically connected to the power supply output port of the power supply 4.

[0035] The cathode chamber of the cation membrane electrolytic cell 1 and the anode chamber of the cation membrane electrolytic cell 1 are in parallel and sealed and butted at the openings, and a cation exchange membrane 8 is arranged between the cathode chamber of the cation membrane electrolytic cell 1 and the anode chamber of the cation membrane electrolytic cell 1. The anode chamber liquid inlet port 5A of the cation membrane electrolytic cell 1 and the anode chamber liquid outlet port 6A of the cation membrane electrolytic cell 1 are each connected to the salt liquid circulating tank 2. The cathode chamber liquid inlet port of the cation membrane electrolytic cell 1 and the cathode chamber liquid outlet port of the cation membrane electrolytic cell 1 are connected by an external circulating pipe A9. The circulating pipe A9 is provided with a circulating pump A and a three-way valve A in series. One port of the three-way valve A is connected to a product alkali storage tank. The anode chamber gas outlet port 7A of the cation membrane electrolytic cell 1 is connected to a chlorine gas collection and treatment device, and the cathode chamber gas outlet port of the cation membrane electrolytic cell 1 is connected to a hydrogen gas collection or treatment device.

[0036] The anion membrane electrolytic cell 3 has the same structure as the cation membrane electrolytic cell 1, and an anion exchange membrane 10 is arranged between the cathode chamber of the anion membrane electrolytic cell 3 and the anode chamber of the anion membrane electrolytic cell 3. The cathode chamber liquid inlet port 5 of the anion membrane electrolytic cell 3 and the cathode chamber liquid outlet port 6 of the anion membrane electrolytic cell 3 are each connected to the salt liquid circulating tank 2. The anode chamber liquid inlet port of the anion membrane electrolytic cell 3 and the anode chamber liquid outlet port of the anion membrane electrolytic cell 3 are connected by an external circulating pipe B. The circulating pipe B is provided with a circulating pump B and a three-way valve B18 in series. One port of the three-way valve B18 is connected to a product acid storage tank. The anode chamber gas outlet port of the anion membrane electrolytic cell 3 is connected to a chlorine gas collection and treatment device, and the cathode chamber gas outlet port 7 of the anion membrane electrolytic cell 3 is connected to a hydrogen gas collection or treatment device.

[0037] The anodes of the cation membrane electrolytic cell 1 and the anion membrane electrolytic cell 3 are titanium mesh or titanium plates with ruthenium iridium or iridium tantalum oxide coating, and the cathodes are titanium mesh or titanium plates. The spacing between the anode and the cathode is 1-4 cm.

[0038] The chlorine collection treatment device is a chlorine detoxification device 11, the gas inlets of the chlorine detoxification device 11 are communicated with the anode chamber gas outlets 7A of the cation membrane electrolytic cell 1 and the anode chamber gas outlets of the anion membrane electrolytic cell 3 respectively, and the feed inlet of the chlorine detoxification device 11 is communicated with the three-way valve A connected in series on the external circulation pipe A9 of the cathode chamber of the cation membrane electrolytic cell 1.

[0039] The bottom end of the cathode chamber and the anode chamber away from the outlet is provided with an electrode power supply port 12, and the cathode and the anode are respectively fixedly provided with an electrode power supply handle which can move through the electrode power supply port 12 to adjust the position of the electrode, and the electrode power supply handle is electrically connected with the power supply output port of the power supply 4.

[0040] A plurality of threaded holes are respectively arranged on the side walls of the cathode chamber and the anode chamber, the cathode chamber and the anode chamber are fixedly connected through screws penetrating the threaded holes, the cation exchange membrane 8 or the anion exchange membrane 10 is fixedly arranged between the open end faces of the cathode chamber and the anode chamber, and airtight silica gel pads are further arranged between the open end faces of the cathode chamber and the anode chamber.

[0041] The airtight silica gel pads are square pads consistent with the shapes of the open end faces of the cathode chamber and the anode chamber.

[0042] The screw directions of the corresponding threaded holes on the side walls of the cathode chamber and the anode chamber are opposite.

[0043] As shown in the drawings, Figures 1 to 4 The lead-zinc smelting high-chlorine sodium sulfate wastewater electrolysis method of the application comprises pretreatment, coupled electrolysis and post-treatment steps, and the specific content is as follows:

[0044] A, pretreatment: the lead-zinc smelting high-chlorine sodium sulfate wastewater is mixed with alkali or the alkali obtained in the coupled electrolysis step, then impurities are removed by suction filtration to obtain high-salt wastewater containing chlorine;

[0045] B, coupled electrolysis: the high-salt wastewater containing chlorine is introduced into the salt liquid circulation tank 2, then the high-salt wastewater containing chlorine in the salt liquid circulation tank 2 is continuously circulated and electrolyzed in the anode chamber of the cation membrane electrolytic cell 1 and the cathode chamber of the anion membrane electrolytic cell 3 through the circulation pump 17 respectively, at the same time, the cathode liquid in the cathode chamber of the cation membrane electrolytic cell 1 is continuously circulated through the circulation pump A, and the anode liquid in the anode chamber of the anion membrane electrolytic cell 3 is continuously circulated through the circulation pump B, when the alkali in the cathode liquid in the cathode chamber of the cation membrane electrolytic cell 1 reaches a preset concentration, the cathode liquid is discharged to the product alkali storage tank through the three-way valve A, and when the acid in the anode liquid in the anode chamber of the anion membrane electrolytic cell 3 reaches a preset concentration, the anode liquid is discharged to the product acid storage tank through the three-way valve B 18;

[0046] C. Post-processing: Collect the hydrogen gas discharged from the gas outlet of the cathode chamber of the cation membrane electrolyzer 1, and pass the chlorine gas and oxygen gas discharged from the gas outlet 7A of the anode chamber of the cation membrane electrolyzer 1 and the gas outlet of the anode chamber of the anion membrane electrolyzer 3 into the chlorine gas collection and processing device storing the alkali diluent, to absorb the toxic chlorine gas and discharge clean oxygen gas.

[0047] The SS in the high-salt wastewater containing chlorine after impurity removal in the pretreatment step is less than 50 mg / L, and the pH is greater than or equal to 9.8, and the sodium sulfate concentration is greater than 0.35 mol / L; the sum of the volumes of the salt solution in the salt solution circulating tank 2, the anode chamber of the cation membrane electrolyzer 1, and the cathode chamber of the anion membrane electrolyzer 3 in the coupled electrolysis step is at least 1.5 times the sum of the volumes of the anode chamber of the cation membrane electrolyzer 1 and the cathode chamber of the anion membrane electrolyzer 3.

[0048] The current density in the coupled electrolysis step is 20-100 mA / cm 2 , and the electrolyte in the cathode chamber and the anode chamber is circulated once every 3-5 min.

[0049] When the suspended substance concentration in the high-salt wastewater containing chlorine in the salt solution circulating tank 2 in the coupled electrolysis step is greater than 100 mg / L or the H + concentration is greater than 1.0 mol / L, the high-salt wastewater containing chlorine is pumped to the pretreatment step for treatment.

[0050] The high-salt wastewater containing chlorine is continuously circulated and electrolyzed for more than 3 h in the coupled electrolysis step, and the removal rate of chlorides is 90-95%.

[0051] In the coupled electrolysis step, when the alkali concentration in the catholyte in the cathode chamber of the cation membrane electrolyzer 1 reaches the preset requirement, the catholyte is discharged to the product alkali storage tank; when the acid concentration in the anolyte in the anode chamber of the anion membrane electrolyzer 3 reaches the preset requirement, the anolyte is discharged to the product acid storage tank. The acid and alkali concentrations in the electrode solution can be determined according to the continuous electrolysis time, for example, 1 h of electrolysis of 0.5 mol / L sodium sulfate can produce more than 3.5% of acid and alkali.

[0052] In the coupled electrolysis, deionized water or a 0.5-1% sodium hydroxide solution is introduced into the cathode chamber of the cation membrane electrolyzer 1 before electrolysis starts, and deionized water or a 0.5-1% sulfuric acid solution is introduced into the anode chamber of the anion membrane electrolyzer 3 before electrolysis starts.

[0053] In the post-processing step, the alkali diluent is the alkali-containing catholyte discharged from the cathode chamber of the cation membrane electrolyzer 1 diluted to 1.0-1.5% sodium hydroxide.

[0054] Example

[0055] The electrolysis method of the present invention was used to electrolyze lead-zinc smelting sodium sulfate wastewater collected from a lead-zinc smelter in Huize, Yunnan. The main pollutants in the wastewater are shown in Table 1.

[0056] Table 1 Pollutant composition of chlorine-containing high-salt wastewater (unit: dimensionless pH, conductivity ms / cm, arsenic μg / L)

[0057]

[0058] S100: Add the sodium hydroxide obtained in step S200 to the above-mentioned lead-zinc smelting sodium sulfate wastewater, stir and mix, and then use a suction pump to filter out impurities therein to obtain chlorine-containing high-salt wastewater with SS less than 50 mg / L, pH greater than 9.8, and sodium sulfate concentration greater than 0.35 mol / L.

[0059] S200: 500 mL of the above-mentioned high-salt wastewater after impurity removal is passed into the salt solution circulation tank 2, and then the chlorine-containing high-salt wastewater at room temperature is electrolyzed in the anode chamber of the cationic membrane electrolyzer 1 and the cathode chamber of the anionic membrane electrolyzer 3 in a continuous cycle through the circulation pump 17;

[0060] Parameters of the cationic membrane electrolyzer 1 are as follows: the cathode is a titanium mesh of 8.4 cm × 8.4 cm, the anode is a titanium ruthenium-plated iridium mesh of 8.4 cm × 8.4 cm × 0.1 cm, the distance between the anode and the cathode is 10 mm, the effective area of ​​the cation exchange membrane 8 is 8.4 cm × 8.4 cm, and the initial cathode liquid introduced into the cathode chamber is 125 mL of 1% sodium hydroxide.

[0061] Parameters of the anion membrane electrolyzer 3: the cathode is a titanium mesh of 8.4 cm × 8.4 cm × 0.1 cm, the anode is a titanium ruthenium-plated iridium mesh of 8.4 cm × 8.4 cm × 0.1 cm, the distance between the anode and the cathode is 10 mm, the effective area of ​​the anion exchange membrane 10 is 8.4 cm × 8.4 cm, and the initial anolyte introduced into the anode chamber is 125 mL of a 1% concentration sulfuric acid solution.

[0062] In order to compare the effects of coupled electrolysis, one-membrane two-chamber electrolysis and two-membrane three-chamber electrolysis, the electrolysis time was set to 3 h, and the constant current of the electrolysis process was controlled at 5.0 A; the circulation flow rates of the anolyte, cathode liquid and chlorine-containing high-salt wastewater were all controlled at 100 mL / min.

[0063] During the coupled electrolysis process, the H content in the circulating salt chamber was detected every 30 minutes. + Concentration, when H + When the concentration is greater than 1.0 mol / L, the salt solution in the circulating salt chamber is continuously pumped to the pretreatment process to adjust the pH to greater than 9.8.

[0064] S300: Collect hydrogen gas discharged from the cathode chamber gas outlet of the cation membrane electrolyzer 1, and pass the chlorine gas and oxygen gas discharged from the anode chamber gas outlet 7A of the cation membrane electrolyzer 1 and the anode chamber gas outlet of the anion membrane electrolyzer 3 into the chlorine detoxification device 11 storing a 1% concentration of sodium hydroxide solution, absorb the toxic chlorine gas, and discharge clean oxygen gas.

[0065] After the coupling electrolysis 3h, the cathode chamber of the cation membrane electrolyzer 1 produces 130g / L of sodium hydroxide, and the electrolysis efficiency is 73%; the anode chamber of the anion membrane electrolyzer 3 produces 150g / L of sulfuric acid solution, and the electrolysis efficiency is 65%. The chloride ion concentration in the salt solution circulating tank 2 is reduced to 303mg / L.

[0066] Comparative Example 1

[0067] The chlorine-containing high-salt wastewater obtained by electrolysis of the step of Example S100 is electrolyzed using a membrane two-chamber electrolyzer.

[0068] Electrolyzer parameters: the cathode is a titanium mesh of 8.4x8.4cmx0.1cm, the anode is a titanium mesh coated with ruthenium and iridium of 8.4x8.4cmx0.1cm, the distance between the anode and the cathode is 10mm; the effective area of the cation exchange membrane is 8.4x8.4cm; the initial catholyte in the cathode chamber is 125mL of 1% sodium hydroxide; the anolyte (including the circulating tank) is 500mL of the above-mentioned chlorine-containing high-salt wastewater.

[0069] The chlorine-containing high-salt wastewater is circulated and electrolyzed in the anode chamber at room temperature, and the catholyte in the cathode chamber is circulated synchronously during the electrolysis process. The electrolysis process is controlled at a constant current of 5.0A; the circulation flow rate of the catholyte and the salt solution into the anode chamber is controlled at 100mL / min, and electrolysis is carried out for 3h. The anode exhaust gas (oxygen and chlorine) generated in the anode chamber during electrolysis is absorbed by 1% sodium hydroxide.

[0070] After electrolysis for 3h, the cathode chamber produces 84g / L of sodium hydroxide, and the electrolysis efficiency is 51%; the anode chamber produces 86g / L of sulfuric acid-sodium sulfate mixed solution, and the electrolysis efficiency is 38%, and the chloride ion concentration in the sulfuric acid-sodium sulfate mixed solution is 289mg / L.

[0071] Comparative Example 2

[0072] The chlorine-containing high-salt wastewater obtained by electrolysis of the step of Example S100 is electrolyzed using a two-membrane three-chamber electrolyzer.

[0073] Electrolytic cell parameters: the cathode is 8.4x8.4cmx0.1cm titanium mesh, the anode is 8.4x8.4cmx0.1cm titanium mesh plated with ruthenium and iridium, the distance between the anode and the cathode is 50mm (due to the structural characteristics of the electrolytic cell, the distance between the electrodes cannot be controlled at 10mm, the minimum distance of the cell type design is 50mm); the effective area of the cation and anion exchange membrane is 8.4x8.4cm; the initial catholyte in the cathode chamber is 125mL of 1% sodium hydroxide solution; the initial anolyte in the anode chamber is 125mL of 1% sulfuric acid solution; the initial salt in the middle salt chamber (including the circulating pool) is 500mL of the above-mentioned high-salt wastewater containing chlorine.

[0074] The high-salt wastewater containing chlorine is introduced into the middle salt chamber and circulated electrolysis for 3h at room temperature, while the catholyte in the cathode chamber and the anolyte in the anode chamber are circulated synchronously during the electrolysis process. The electrolysis process is controlled at a constant current of 5.0A. The anode exhaust gas (oxygen and chlorine) generated in the anode chamber during electrolysis is absorbed with 1% sodium hydroxide.

[0075] After 3h of electrolysis, 73g / L of sodium hydroxide is produced in the cathode chamber, and the electrolysis efficiency is 62%; 80g / L of sulfuric acid is produced in the anode chamber, and the electrolysis efficiency is 51%, and the chloride ion concentration in the salt chamber is reduced to 5988mg / L (without chlorine removal effect).

[0076] Compared with the electrolysis method of the embodiment (i.e. the coupled electrolytic cell electrolysis technology), the membrane two-chamber electrolysis technology of Comparative Example 1 and the two-membrane three-chamber electrolysis technology of Comparative Example 2, under basically the same conditions, the coupled electrolytic cell electrolysis technology can effectively treat the high-salt wastewater containing chlorine in the lead-zinc smelting industry, and completely separate the electrolysis products acid and alkali, and the concentration of the produced product acid and alkali is much higher than that of the two electrolysis technologies of the comparative examples, and the electrolysis efficiency is also much higher than that of the electrolysis technologies of the comparative examples.

[0077] The above only describes the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical range disclosed by the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A lead-zinc smelting sodium sulfate wastewater electrolysis device, characterized in that The invention comprises a cationic membrane electrolyzer (1), a salt solution circulation tank (2), an anionic membrane electrolyzer (3), and a power supply (4). The cationic membrane electrolyzer (1) and the anionic membrane electrolyzer (3) are respectively provided with a cathode chamber and an anode chamber on both sides of the ion membrane. The cathode chamber and the anode chamber are both frame-shaped structures with one end open and the side walls are provided with a liquid inlet, a liquid outlet, and a gas outlet penetrating inside and outside. A cathode with an adjustable spacing is provided in the cathode chamber, and an anode with an adjustable spacing is provided in the anode chamber. The cathode and the anode are respectively electrically connected to the power output port of the power supply (4); The cathode chamber of the cationic membrane electrolyzer (1) and the anode chamber of the cationic membrane electrolyzer (1) are parallelly and sealedly docked with each other, and a cation exchange membrane (8) is arranged between the cathode chamber of the cationic membrane electrolyzer (1) and the anode chamber of the cationic membrane electrolyzer (1), the anode chamber liquid inlet (5A) of the cationic membrane electrolyzer and the anode chamber liquid outlet (6A) of the cationic membrane electrolyzer are respectively connected to the salt solution circulation tank (2), the cathode chamber liquid inlet of the cationic membrane electrolyzer and the cathode chamber liquid outlet of the cationic membrane electrolyzer are connected through an external circulation pipe A (9), a circulation pump A and a three-way valve A are connected in series on the circulation pipe A (9), one port of the three-way valve A is connected to the product alkali storage tank, the anode chamber gas outlet (7A) of the cationic membrane electrolyzer is connected to the chlorine collection and treatment device, and the cathode chamber gas outlet of the cationic membrane electrolyzer is connected to the hydrogen collection or treatment device; The anion membrane electrolyzer (3) has the same structure as the cation membrane electrolyzer (1), and the anion exchange membrane (10) is arranged between the cathode chamber of the anion membrane electrolyzer (3) and the anode chamber of the anion membrane electrolyzer (3). The cathode chamber liquid inlet (5) and the cathode chamber liquid outlet (6) of the anion membrane electrolyzer are respectively connected to the salt solution circulation tank (2). The anode chamber liquid inlet and the anode chamber liquid outlet of the anion membrane electrolyzer are connected through an external circulation pipe B. A circulation pump B and a three-way valve B (18) are connected in series on the circulation pipe B. One port of the three-way valve B (18) is connected to the product acid storage tank. The anode chamber gas outlet of the anion membrane electrolyzer (3) is connected to a chlorine gas collection and treatment device, and the cathode chamber gas outlet (7) of the anion membrane electrolyzer (3) is connected to a hydrogen gas collection or treatment device.

2. The lead-zinc smelting sodium sulfate wastewater electrolysis device according to claim 1, characterized in that The anodes of the cationic membrane electrolyzer (1) and the anionic membrane electrolyzer (3) are titanium mesh or titanium plate with ruthenium-iridium or iridium-tantalum oxide coatings, and the cathodes are titanium mesh or titanium plate, respectively. The distance between the anode and the cathode is 1 to 4 cm.

3. The lead-zinc smelting sodium sulfate wastewater electrolysis device according to claim 1, characterized in that The chlorine gas collection and treatment device is a chlorine gas detoxification device (11), the air inlet of the chlorine gas detoxification device (11) is respectively connected to the anode chamber air outlet (7A) of the cation membrane electrolyzer (1) and the anode chamber air outlet of the anion membrane electrolyzer (3), and the feed port of the chlorine gas detoxification device (11) is connected to the three-way valve A connected in series on the external circulation pipe A (9) of the cathode chamber of the cation membrane electrolyzer (1).

4. The lead-zinc smelting sodium sulfate wastewater electrolysis device according to claim 1, characterized in that The cathode chamber and the anode chamber are provided with an electrode power port penetrating the bottom ends away from the openings, and the cathode and the anode are respectively fixed with an electrode power handle that can be moved through the electrode power port to adjust the electrode position, and the electrode power handle is electrically connected to the power output port of the power supply (4).

5. The lead-zinc smelting sodium sulfate wastewater electrolysis device according to any one of claims 1 to 4, characterized in that The side walls of the cathode chamber and the anode chamber are respectively provided with a plurality of threaded holes, and the cathode chamber and the anode chamber are connected and fixed by screws inserted into the threaded holes. The cation exchange membrane (8) or the anion exchange membrane (10) is fixedly arranged between the open end faces of the cathode chamber and the anode chamber, and a sealed silica gel pad is also arranged between the open end faces of the cathode chamber and the anode chamber.

6. An electrolysis method based on the lead-zinc smelting sodium sulfate electrolysis device according to any one of claims 1 to 5, characterized in that It includes pretreatment, coupled electrolysis, and post-treatment steps, specifically: A. Pretreatment: The high-chloride sodium sulfate wastewater from the lead and zinc smelting process is mixed with the alkali obtained from the coupled electrolysis step, and then filtered to remove impurities to obtain high-chloride salt wastewater; B. Coupled electrolysis: the chlorine-containing high-salt wastewater is introduced into the salt solution circulation tank (2), and then the chlorine-containing high-salt wastewater in the salt solution circulation tank (2) is continuously circulated and electrolyzed in the anode chamber of the cation membrane electrolyzer (1) and the cathode chamber of the anion membrane electrolyzer (3) respectively through the circulation pump (17). At the same time, the cathode liquid in the cathode chamber of the cation membrane electrolyzer (1) is continuously circulated through the circulation pump A, and the anode liquid in the anode chamber of the anion membrane electrolyzer (3) is continuously circulated through the circulation pump B. When the alkali in the cathode liquid in the cathode chamber of the cation membrane electrolyzer (1) reaches a preset concentration, the wastewater is discharged to the product alkali storage tank through the three-way valve A. When the acid in the anode liquid in the anode chamber of the anion membrane electrolyzer (3) reaches a preset concentration, the wastewater is discharged to the product acid storage tank through the three-way valve B (18); C. Post-treatment: collect and utilize or burn the hydrogen discharged from the cathode chamber outlet of the cation membrane electrolyzer (1), and pass the chlorine and oxygen discharged from the anode chamber outlet (7A) of the cation membrane electrolyzer (1) and the anode chamber outlet of the anion membrane electrolyzer (3) into a chlorine collection and treatment device storing an alkali dilution solution, absorb the toxic chlorine, and discharge clean oxygen.

7. The electrolysis method according to claim 6, characterized in that In the pretreatment step, the SS in the chlorine-containing high-salt wastewater after impurities are removed is less than 50 mg / L, the pH is ≥9.8, and the sodium sulfate concentration is greater than 0.35 mol / L; in the coupled electrolysis step, the sum of the volumes of the salt solutions in the salt solution circulation tank (2), the anode chamber of the cation membrane electrolyzer (1), and the cathode chamber of the anion membrane electrolyzer (3) is at least 1.5 times the sum of the volumes of the anode chamber of the cation membrane electrolyzer (1) and the cathode chamber of the anion membrane electrolyzer (3).

8. The electrolysis method according to claim 6, characterized in that The current density of the electrolysis in the coupled electrolysis step is 20-100 mA / cm 2 The electrolyte in the cathode chamber and the anode chamber circulates once every 3 to 5 minutes; in the coupled electrolysis step, the suspended solids concentration in the chlorine-containing high-salt wastewater in the salt solution circulation tank (2) is greater than 100 mg / L or H + When the concentration is greater than 1.0 mol / L, the chlorine-containing high-salt wastewater is pumped to the pretreatment step for treatment.

9. The electrolysis method according to claim 6, characterized in that In the coupled electrolysis step, when the alkali concentration in the cathode liquid in the cathode chamber of the cation membrane electrolyzer (1) reaches a preset requirement, the solution is discharged to the product alkali storage tank; when the acid concentration in the anode liquid in the anode chamber of the anion membrane electrolyzer (3) reaches a preset requirement, the solution is discharged to the product acid storage tank.

10. The electrolysis method according to claim 6, characterized in that In the coupled electrolysis, deionized water or a 0.5-1% sodium hydroxide solution is introduced into the cathode chamber of the cationic membrane electrolyzer (1) before electrolysis begins, and deionized water or a 0.5-1% sulfuric acid solution is introduced into the anode chamber of the anionic membrane electrolyzer (3) before electrolysis begins.

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