Device and process system for resource utilization of by-product salt

Abstract

The invention discloses a device and a process system for resource utilization of by-product salt, comprising a membrane filter, a saturated brine tank and a composite membrane electrolyzer connected in sequence, a saturated brine delivery pipeline and a saturated brine delivery pump are arranged between the saturated brine tank and the composite membrane electrolyzer, the composite membrane electrolyzer comprises a number of electrolyzer units, each electrolyzer unit comprises an anode chamber and a cathode chamber, a diaphragm is arranged between the anode chamber and the cathode chamber, and the diaphragm is a fluorine-containing fiber composite membrane; a cathode gas discharge hose and a cathode liquid outlet hose are respectively arranged on the cathode chamber, the cathode gas discharge hose is respectively connected to the hydrogen main pipe, the cathode liquid outlet hose is connected to a monolithic cathode liquid outlet pipe, the monolithic cathode liquid outlet pipe in each electrolyzer unit is connected to the cathode liquid main pipe, and the monolithic cathode liquid outlet pipe realizes the adjustment of the liquid outlet height through a monolithic cathode liquid level regulator. The invention realizes the large-scale and efficient utilization of by-product salt.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of by-product salt, and in particular to a device and a process system for resource utilization of by-product salt. Background Art

[0002] The chemical industry, especially the petrochemical, coal chemical, fine chemical and intermediate industries, produces a large amount of by-product salt such as waste sodium chloride every year. Since by-product salt contains various impurities, it cannot enter the production system with high requirements for raw materials and becomes waste salt. It has become a bottleneck problem for the sustainable development of the industry and a key issue that the society, the public and government departments pay close attention to.

[0003] If waste salt is recycled, it will first reduce the harm to the environment, and at the same time, electrolysis of waste salt can produce basic chemical raw materials, increasing the company's output value and profits. Therefore, it is necessary to carry out research and development of recycling technology for by-product waste salt. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a device and process system for resource utilization of by-product salt, aiming to achieve large-scale and efficient resource utilization of by-product salt. The specific technical solution is as follows:

[0005] A device for resource utilization of by-product salt comprises a membrane filter, a saturated brine tank and a composite membrane electrolyzer which are connected in sequence according to a process for treating saturated brine of by-product salt, a saturated brine delivery pipeline is arranged between the saturated brine tank and the composite membrane electrolyzer, a saturated brine delivery pump is arranged on the saturated brine delivery pipeline, the composite membrane electrolyzer comprises a number of electrolyzer units, each of the electrolyzer units comprises an anode chamber and a cathode chamber, a diaphragm is arranged between the anode chamber and the cathode chamber, and the diaphragm is a fluorine-containing fiber composite membrane; a cathode gas exhaust hose and a cathode liquid outlet hose are respectively arranged on the cathode chamber, the cathode gas exhaust hose in each electrolyzer unit is respectively connected to a hydrogen main pipe, the cathode liquid outlet hose is connected to a monolithic cathode liquid outlet pipe, the monolithic cathode liquid outlet pipe in each electrolyzer unit is connected to a cathode liquid main pipe, and the monolithic cathode liquid outlet pipe adjusts the height of the liquid outlet through a monolithic cathode liquid level regulator.

[0006] Wherein, the single cathode liquid outlet pipe in each electrolytic cell unit is also connected to the waste liquid main pipe through a stop valve.

[0007] In the present invention, the anode chamber and the cathode chamber are connected around each other to achieve sealing through rubber gaskets and rigid flanges, and the anode in each electrolytic cell unit and the cathode in each electrolytic cell unit are respectively connected in series by conductive devices.

[0008] In the present invention, an anode liquid inlet hose and an anode liquid outlet hose are respectively provided on the anode chamber, the anode liquid inlet hose in each electrolytic cell unit is respectively connected to the anode liquid inlet main pipe, the anode liquid outlet hose in each electrolytic cell unit is respectively connected to the anode main pipe serving as the anode high-level tank, and a monolithic gas-liquid separator is provided between the anode liquid outlet hose and the anode main pipe.

[0009] Preferably, a brine heat exchanger is provided on the saturated brine delivery pipeline, and the brine heat exchanger is connected to a low-pressure steam pipeline.

[0010] In the present invention, the fluorine-containing material fiber composite membrane is prepared by the following method:

[0011] (1) Slurry preparation: adding a certain proportion of fluorine-containing material fibers and mineral powder filler materials to an aqueous solution containing sodium chloride and sodium hydroxide, stirring and mixing them thoroughly, and adding a certain proportion of PTFE emulsion to make the fluorine-containing material fibers hydrophilic, and then stirring and mixing the mixed solution at a set mixing temperature through a reactor at a high speed, so that the fluorine-containing material fibers form a network structure in the mixed solution, and the mineral powder filler materials and the aqueous solution of sodium chloride and sodium hydroxide are evenly filled in the grid space of the network structure, thereby forming a uniformly dispersed slurry;

[0012] (2) Slurry adsorption: The cathode of the electrolytic cell is horizontally contacted with the adsorption slurry or immersed in the adsorption slurry, so that the uniformly dispersed slurry is adsorbed on the cathode of the electrolytic cell, thereby forming a wet film on the surface of the cathode of the electrolytic cell;

[0013] (3) Drying of wet film: Drying a layer of wet film on the cathode surface of the electrolytic cell at a set drying temperature to form a dry film. The sodium chloride in the wet film forms crystals after drying and is evenly mixed in the mineral powder filling material of the dry film.

[0014] (4) Sintering into a fluorine-containing material fiber composite membrane: After the wet membrane is dried, it is sintered at a set sintering temperature so that the fluorine-containing material fibers in the dry membrane are firmly bonded together to form a network bonding structure; at the same time, micropores are formed between the mineral powder filling material and the fluorine-containing material fibers, and between the mineral powder filling material particles and the mineral powder filling material particles through the sintering of the dry membrane. The micropores serve as the first microporous channels for the brine on the fluorine-containing material fiber composite membrane during electrolysis. During electrolysis, sodium chloride crystals are dissolved to form the second microporous channels for the brine on the fluorine-containing material fiber composite membrane.

[0015] Wherein, the fluorine-containing material is a fluorine polymer, and the fluorine-containing material fiber is a fluorine polymer fiber.

[0016] Preferably, the fluoropolymer is one of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene-propylene copolymer, perfluoroalkoxy resin, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, polyvinylidene fluoride, and polyvinyl fluoride.

[0017] Preferably, the mineral powder filling material is one of titanium dioxide powder, zirconium dioxide powder and hydrated magnesium silicate.

[0018] In the present invention, the preparation of the fluorine-containing material fiber composite membrane includes the following process steps:

[0019] S1. Preparation of precursor: dissolve sodium chloride and sodium hydroxide in pure water to form a mixed solution of 13% to 15% sodium chloride and 13% to 15% sodium hydroxide by mass ratio, add fluorine-containing material fibers, mineral powder filler materials and pure water in a mass ratio of 1: (2 to 9): (40 to 160) to the sodium chloride / sodium hydroxide solution, stir and mix at a high speed of 900 to 5400 r / min in a reaction kettle, and keep the system temperature at 30 to 45°C to uniformly disperse the fluorine-containing material fibers;

[0020] S2. Slurry preparation: add PTFE emulsion at a mass ratio of 4:1 to fiber under high-speed stirring, continue high-speed stirring, maintain the system temperature at 30-45°C, make the material uniform, and form slurry;

[0021] S3, membrane adsorption molding: on the cathode of the electrolytic cell, the slurry is adsorbed horizontally or immersed to form a composite membrane;

[0022] S4, drying: drying temperature 80 ~ 130 ℃;

[0023] S5, sintering: sintering temperature 120 ~ 345 ℃;

[0024] Wherein, the fluorine-containing material is a fluorine polymer, and the fluorine-containing material fiber is a fluorine polymer fiber;

[0025] Preferably, the fluoropolymer is one of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene-propylene copolymer, perfluoroalkoxy resin, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, polyvinylidene fluoride, and polyvinyl fluoride.

[0026] Wherein, the mineral powder filling material is one of titanium dioxide powder, zirconium dioxide powder and hydrous magnesium silicate;

[0027] The fluorine-containing material fiber has a diameter of 2 to 3 μm and a length of 4 to 10 mm; during drying, the temperature is increased step by step from 80°C to 100°C to 120°C; during sintering, the temperature is increased step by step from 120°C to 170°C to 220°C to 270°C to 320°C to 330°C to 340°C to 345°C, and the sintering is performed at 330-345°C for 2 to 3 hours.

[0028] The film-forming mechanism of the fluorine-containing fiber composite membrane in the present invention is as follows: in the slurry system, the PTFE emulsion makes the fluorine-containing fiber hydrophilic and can be evenly dispersed in the slurry system. In the composite membrane formed by vacuum adsorption, the fluorine-containing fiber is crisscrossed to form a grid, and the mineral powder filling material is filled therein, and micropores are formed between the mineral powder filling material and the fluorine-containing fiber and between the particles of the mineral powder filling material and the mineral powder filling material; in addition, during the drying process, the sodium chloride in the slurry is crystallized and sandwiched in the mineral powder filling material, and the sodium chloride crystals are dissolved during driving to form micropores, which become the channel of the salt water on the composite membrane; after sintering, the fluorine-containing fiber itself can be firmly bonded together to form a mesh structure, thereby enhancing the mechanical properties of the composite membrane, so that the fluorine-containing fiber composite membrane has a longer life. During the electrolysis process, the salt water forms Cl2 in the anode chamber, and Cl2 overflows through the gas channel. The liquid enters the cathode chamber through the micropores under the drive of a certain liquid level difference, and forms NaOH and H2 in the cathode chamber.

[0029] A process system for resource utilization of by-product salt comprises a membrane filter, a saturated brine tank, a composite membrane electrolytic cell and an electrolysis product utilization unit which are sequentially arranged according to a process flow for treating saturated brine of the by-product salt. The electrolysis product utilization unit comprises a chlorine utilization unit and a caustic soda utilization unit. The alkaline solution produced by the composite membrane electrolytic cell is delivered to the caustic soda utilization unit through a conveying system after being subjected to system power-off treatment. The chlorine produced by the composite membrane electrolytic cell is delivered to the chlorine utilization unit through a gas suction and pressurizing device.

[0030] Among them, a chlorine delivery pipeline is connected between the composite membrane electrolyzer and the chlorine utilization unit, a caustic soda delivery pipeline is connected between the composite membrane electrolyzer and the caustic soda utilization unit, and a cooling circulation loop is connected between the chlorine delivery pipeline and the caustic soda delivery pipeline, the cooling circulation loop exchanges heat with the chlorine delivery pipeline through a chlorine cooler, and the cooling circulation loop exchanges heat with the caustic soda delivery pipeline through a caustic soda cooler.

[0031] Preferably, the caustic soda and chlorine products are continuously used in the electrolysis product utilization unit to regenerate by-product salt.

[0032] The invention can be used for resource utilization of chemical by-product salt, and converts sodium chloride with high organic matter content into sodium hydroxide for resource utilization.

[0033] In the present invention, during the operation of the composite membrane electrolyzer, except for adding salt water to the anode, the cathode does not need to consume materials. The fluorine-containing fiber composite membrane on the unit electrolyzer has an acceptance range of less than 200ppm for the organic matter content in the by-product salt and a service life of more than 5 years.

[0034] In the present invention, the by-product salt resource utilization device is composed of a plurality of unit electrolytic cells connected in series, with a single effective area of ​​0.5 to 3.3 m2. A single device can be configured with 1 to 200 unit electrolytic cells according to actual needs, with an operating current density of 0 to 2 KA / m2, a generated sodium hydroxide concentration of 0 to 16%, a chlorine purity of >98%, a hydrogen purity of >99%, a current efficiency of >0.95%, and a flexible configuration, and the annual by-product salt processing capacity can reach 10,000 tons or more.

[0035] The process flow of by-product salt treatment of the present invention is as follows:

[0036] (1) The saturated brine of the by-product salt is filtered through the membrane filter to form a saturated brine with the following properties: NaCl concentration 300-315 g / l, Ca 2+ and Mg 2+ Concentration ≤10mg / l, SO4 2- Concentration, NaClO3 concentration, suspended matter concentration, TOC concentration ≤ 200 mg / l, pH value 9-10, temperature ≥ 50℃, 0.2MpaG.

[0037] (2) The saturated brine of the by-product salt is filtered through the membrane filter and enters the saturated brine tank, and then enters the brine heat exchanger through the brine delivery pump for heat exchange, is heated to between 65 and 80° C., and enters the anode high-level tank of the composite membrane electrolyzer. Under the action of gravity, the by-product brine enters the interior of the composite membrane electrolyzer. The cathode chamber and the anode chamber in the composite membrane electrolyzer are separated by a fluorine-containing fiber composite membrane. Under the action of the fluorine-containing fiber composite membrane and the current, the chloride ions and sodium ions in the anode chamber are separated, and the chloride ions are converted into chlorine gas. The sodium ions and part of the sodium chloride solution pass through the composite membrane into the cathode chamber. In the cathode chamber, the sodium ions combine with the hydroxide ions decomposed by water to form sodium hydroxide, and the hydrogen ions are converted into hydrogen gas.

[0038] (3) Chlorine gas is delivered to the chlorine utilization unit through a gas suction and pressurization device, and sodium hydroxide (caustic soda) is delivered to the caustic soda utilization unit.

[0039] (4) In the chlorine utilization unit and the caustic soda utilization unit, the by-product salt is regenerated after the caustic soda and chlorine products are used, thereby forming a recycling utilization of the by-product salt resources.

[0040] The beneficial effects of the present invention are:

[0041] First, the present invention provides a device and process system for resource utilization of by-product salt. The diaphragm between the cathode chamber and the anode chamber of the composite membrane electrolyzer of the device for resource utilization of by-product salt adopts a fluorine-containing material fiber composite membrane, which has good adaptability to by-product salt, high electrolysis efficiency and long service life.

[0042] Secondly, in the device and process system for resource utilization of by-product salt of the present invention, the height of the single cathode liquid outlet pipe of the electrolytic cell unit can be freely adjusted, thereby ensuring that the concentration of sodium hydroxide produced is within the control index range.

[0043] Third, the device and process system for resource utilization of by-product salt of the present invention can be equipped with sufficient electrolytic cell units in a set of devices according to the processing volume of by-product salt, thereby realizing large-scale and efficient resource utilization of by-product salt.

[0044] Fourthly, the present invention provides a device and process system for resource utilization of by-product salt. The device is made of titanium, nickel and stainless steel and has a service life of more than 10 years.

[0045] Fifth, the device and process system for resource utilization of by-product salt of the present invention adopts a rapid circulation structure, which is conducive to the escape of bubbles generated by the decomposition of organic matter in the electrolysis chamber, thereby improving the electrolysis efficiency and reducing the electrolysis energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a structural schematic diagram of a device and a process system for resource utilization of by-product salt according to the present invention;

[0047] Figure 2 yes Figure 1 Schematic diagram of the structure of the composite membrane electrolyzer;

[0048] Figure 3 It is a schematic diagram of the preparation process of fluorine-containing material fiber composite membrane;

[0049] Figure 4 It is a trend chart when using fluorine-containing material fiber composite membrane to electrolyze refined brine and electrolyze by-product brine; the bottom coordinate in the figure represents time (hours), the left vertical coordinate represents voltage V (corresponding to curve ①), and the right vertical coordinate represents temperature or alkali concentration (wherein: the right vertical coordinate value corresponding to curve ② represents temperature ℃, and the right vertical coordinate value corresponding to curve ③ represents alkali concentration %).

[0050] In the figure: 1, membrane filter, 2, saturated brine tank, 3, composite membrane electrolyzer, 4, saturated brine delivery pipeline, 5, brine delivery pump, 6, cathode gas discharge hose, 7, cathode liquid outlet hose, 8, hydrogen main pipe, 9, single-chip cathode liquid outlet pipe, 10, cathode liquid main pipe, 11, single-chip cathode liquid level regulator, 12, stop valve, 13, waste liquid main pipe, 14, anode liquid inlet hose, 15, anode liquid outlet hose, 16, anode liquid inlet main pipe, 17, anode main pipe, 18, single-chip gas-liquid separator, 19, brine heat exchanger, 20, low-pressure steam pipeline, 21, chlorine utilization unit, 22, caustic soda utilization unit, 23, gas suction and pressurization device, 24, chlorine delivery pipeline, 25, caustic soda delivery pipeline, 26, cooling circulation loop, 27, chlorine cooler, 28, caustic soda cooler. DETAILED DESCRIPTION

[0051] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0052] Embodiment 1:

[0053] like Figures 1 to 4 The present invention shows an embodiment of a device for resource utilization of by-product salt, comprising a membrane filter 1, a saturated brine tank 2 and a composite membrane electrolyzer 3 connected in sequence according to a process for treating saturated brine of by-product salt, a saturated brine delivery pipeline 4 is arranged between the saturated brine tank 2 and the composite membrane electrolyzer 3, a saturated brine delivery pump 5 is arranged on the saturated brine delivery pipeline 4, the composite membrane electrolyzer 3 comprises a number of electrolyzer units, each of the electrolyzer units comprises an anode chamber and a cathode chamber, a diaphragm is arranged between the anode chamber and the cathode chamber, and the diaphragm is a fluorine-containing fiber composite membrane; a cathode gas exhaust hose 6 and a cathode liquid outlet hose 7 are respectively arranged on the cathode chamber, the cathode gas exhaust hose 6 in each electrolyzer unit is respectively connected to a hydrogen main pipe 8, the cathode liquid outlet hose 7 is connected to a monolithic cathode liquid outlet pipe 9, the monolithic cathode liquid outlet pipe 9 in each electrolyzer unit is connected to a cathode liquid main pipe 10, and the monolithic cathode liquid outlet pipe 9 is adjusted by a monolithic cathode liquid level regulator 11 to adjust the height of the liquid outlet.

[0054] The single cathode liquid outlet pipe 9 in each electrolytic cell unit is also connected to the waste liquid main pipe 13 through a stop valve 12 .

[0055] In this embodiment, the anode chamber and the cathode chamber are connected to each other on all sides to achieve sealing through rubber gaskets and rigid flanges, and the anode in each electrolytic cell unit and the cathode in each electrolytic cell unit are connected in series by conductive devices.

[0056] In this embodiment, an anode liquid inlet hose 14 and an anode liquid outlet hose 15 are respectively provided on the anode chamber, the anode liquid inlet hose 14 in each electrolytic cell unit is respectively connected to an anode liquid inlet main pipe 16, the anode liquid outlet hose 15 in each electrolytic cell unit is respectively connected to an anode main pipe 17 serving as an anode high-level tank, and a monolithic gas-liquid separator 18 is provided between the anode liquid outlet hose 15 and the anode main pipe 17.

[0057] Preferably, a brine heat exchanger 19 is provided on the saturated brine delivery pipeline 4 , and the brine heat exchanger 19 is connected to a low-pressure steam pipeline 20 .

[0058] In this embodiment, the fluorine-containing fiber composite membrane is prepared by the following method:

[0059] (1) Slurry preparation: adding a certain proportion of fluorine-containing material fibers and mineral powder filler materials to an aqueous solution containing sodium chloride and sodium hydroxide, stirring and mixing them thoroughly, and adding a certain proportion of PTFE emulsion to make the fluorine-containing material fibers hydrophilic, and then stirring and mixing the mixed solution at a set mixing temperature through a reactor at a high speed, so that the fluorine-containing material fibers form a network structure in the mixed solution, and the mineral powder filler materials and the aqueous solution of sodium chloride and sodium hydroxide are evenly filled in the grid space of the network structure, thereby forming a uniformly dispersed slurry;

[0060] (2) Slurry adsorption: The cathode of the electrolytic cell is horizontally contacted with the adsorption slurry or immersed in the adsorption slurry, so that the uniformly dispersed slurry is adsorbed on the cathode of the electrolytic cell, thereby forming a wet film on the surface of the cathode of the electrolytic cell;

[0061] (3) Drying of wet film: Drying a layer of wet film on the cathode surface of the electrolytic cell at a set drying temperature to form a dry film. The sodium chloride in the wet film forms crystals after drying and is evenly mixed in the mineral powder filling material of the dry film.

[0062] (4) Sintering into a fluorine-containing material fiber composite membrane: After the wet membrane is dried, it is sintered at a set sintering temperature so that the fluorine-containing material fibers in the dry membrane are firmly bonded together to form a network bonding structure; at the same time, micropores are formed between the mineral powder filling material and the fluorine-containing material fibers, and between the mineral powder filling material particles and the mineral powder filling material particles through the sintering of the dry membrane. The micropores serve as the first microporous channels for the brine on the fluorine-containing material fiber composite membrane during electrolysis. During electrolysis, sodium chloride crystals are dissolved to form the second microporous channels for the brine on the fluorine-containing material fiber composite membrane.

[0063] Wherein, the fluorine-containing material is a fluorine polymer, and the fluorine-containing material fiber is a fluorine polymer fiber.

[0064] Preferably, the fluoropolymer is one of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene-propylene copolymer, perfluoroalkoxy resin, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, polyvinylidene fluoride, and polyvinyl fluoride.

[0065] Preferably, the mineral powder filling material is one of titanium dioxide powder, zirconium dioxide powder and hydrated magnesium silicate.

[0066] In this embodiment, the preparation of the fluorine-containing material fiber composite membrane includes the following process steps:

[0067] S1. Preparation of precursor: dissolve sodium chloride and sodium hydroxide in pure water to form a mixed solution of 13% to 15% sodium chloride and 13% to 15% sodium hydroxide by mass ratio, add fluorine-containing material fibers, mineral powder filler materials and pure water in a mass ratio of 1: (2 to 9): (40 to 160) to the sodium chloride / sodium hydroxide solution, stir and mix at a high speed of 900 to 1400 r / min in a reaction kettle, and keep the system temperature at 30 to 45°C to uniformly disperse the fluorine-containing material fibers;

[0068] S2. Slurry preparation: add PTFE emulsion at a mass ratio of 4:1 to fiber under high-speed stirring, continue high-speed stirring, maintain the system temperature at 30-45°C, make the material uniform, and form slurry;

[0069] S3, membrane adsorption molding: on the cathode of the electrolytic cell, the slurry is adsorbed horizontally or immersed to form a composite membrane;

[0070] S4, drying: drying temperature 80 ~ 130 ℃;

[0071] S5, sintering: sintering temperature 120 ~ 345 ℃;

[0072] Wherein, the fluorine-containing material is a fluorine polymer, and the fluorine-containing material fiber is a fluorine polymer fiber;

[0073] Preferably, the fluoropolymer is one of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene-propylene copolymer, perfluoroalkoxy resin, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, polyvinylidene fluoride, and polyvinyl fluoride.

[0074] Wherein, the mineral powder filling material is one of titanium dioxide powder, zirconium dioxide powder and hydrous magnesium silicate;

[0075] The fluorine-containing material fiber has a diameter of 2 to 3 μm and a length of 4 to 10 mm. The fiber is dried by gradually increasing the temperature from 80°C to 100°C to 120°C. The fiber is sintered by gradually increasing the temperature from 120°C to 170°C to 220°C to 270°C to 320°C to 330°C to 340°C to 345°C, and is sintered at 345°C for 2 hours.

[0076] The film-forming mechanism of the fluorine-containing material fiber composite membrane in this embodiment is as follows: In the slurry system, the PTFE emulsion makes the fluorine-containing material fiber hydrophilic and can be evenly dispersed in the slurry system. In the composite membrane formed by vacuum adsorption, the fluorine-containing material fibers are crisscrossed to form a grid, and the mineral powder filling material is filled therein, and micropores are formed between the mineral powder filling material and the fluorine-containing material fibers and between the particles of the mineral powder filling material and the mineral powder filling material; in addition, during the drying process, the sodium chloride in the slurry is crystallized and sandwiched in the mineral powder filling material, and the sodium chloride crystals will also form micropores after dissolving during driving, which become the channel of the salt water on the composite membrane; after sintering, the fluorine-containing material fibers themselves can be firmly bonded together to form a mesh structure, thereby enhancing the mechanical properties of the composite membrane, so that the fluorine-containing material fiber composite membrane has a longer life. During the electrolysis process, the salt water forms Cl2 in the anode chamber, and Cl2 overflows through the gas channel. The liquid enters the cathode chamber through the micropores under the drive of a certain liquid level difference, and forms NaOH and H2 in the cathode chamber.

[0077] The fluorine-containing fiber composite membrane prepared by the above preparation process was used for electrolysis of refined brine and electrolysis of by-product brine, and the test results were shown in Tables 1 to 4 and Attached Figure 4 :

[0078] Table 1. Refined brine test data

[0079] substance Secondary brine Sodium chloride 308.23g / L calcium 4.773ug / L magnesium 2.651ug / L iron 2.122ug / L aluminum <0.01mg / L barium 2.153ug / L strontium 0.182ug / L nickel <0.01mg / L Sodium chlorate <5g / L Free Chlorine Not detected TOC 5.65mg / L TN 76.52mg / L

[0080] Table 2. Data of composite membrane electrolysis refined brine

[0081]

[0082] Table 3. Byproduct brine detection data

[0083] substance Byproduct salt water Sodium chloride 316.56g / L calcium 4.431mg / L magnesium 0.528mg / L iron 39.12ug / L aluminum 1.002mg / L barium 9.660ug / L strontium 2.12ug / L Sodium hypochlorite 65.02g / L TOC 100.12mg / L TN 16.52mg / L

[0084] Table 4. Data of by-product brine from composite membrane electrolysis

[0085]

[0086] Embodiment 2:

[0087] A process system using the device for resource utilization of by-product salt of Example 1, comprising a membrane filter 1, a saturated brine tank 2, a composite membrane electrolytic cell 3 and an electrolysis product utilization unit arranged in sequence according to a process flow for treating saturated brine of by-product salt, wherein the electrolysis product utilization unit comprises a chlorine utilization unit 21 and a caustic soda utilization unit 22, the alkaline solution produced by the composite membrane electrolytic cell 3 is delivered to the caustic soda utilization unit 22 through a conveying system after system power-off treatment, and the chlorine produced by the composite membrane electrolytic cell 3 is delivered to the chlorine utilization unit 21 through a gas suction and pressurizing device 23.

[0088] Among them, a chlorine delivery pipeline 24 is connected between the composite membrane electrolyzer 3 and the chlorine utilization unit 21, a caustic soda delivery pipeline 25 is connected between the composite membrane electrolyzer 3 and the caustic soda utilization unit 22, and a cooling circulation loop 26 is connected between the chlorine delivery pipeline 24 and the caustic soda delivery pipeline 25, the cooling circulation loop 26 performs heat exchange with the chlorine delivery pipeline 24 through a chlorine cooler 27, and the cooling circulation loop 26 performs heat exchange with the caustic soda delivery pipeline 25 through a caustic soda cooler 28.

[0089] Preferably, the caustic soda and chlorine products are continuously used in the electrolysis product utilization unit to regenerate by-product salt.

[0090] This embodiment can be used for resource utilization of chemical by-product salt, converting sodium chloride with high organic matter content into sodium hydroxide for resource utilization.

[0091] In this embodiment, during the operation of the composite membrane electrolyzer 3, except for adding salt water to the anode, no material is consumed at the cathode. The fluorine-containing fiber composite membrane on the unit electrolyzer has an acceptable range of organic matter content in the by-product salt of <200ppm and a service life of more than 5 years.

[0092] In this embodiment, the by-product salt resource utilization device is composed of multiple unit electrolytic cells connected in series, with a single effective area of ​​0.5 to 3.3 m2. A single device can be configured with 1 to 200 unit electrolytic cells according to actual needs, with an operating current density of 0 to 2KA / m2, a sodium hydroxide concentration of 0 to 16%, a chlorine purity of >98%, a hydrogen purity of >99%, a current efficiency of >0.95%, and flexible configuration. The annual by-product salt processing capacity can reach 10,000 tons or more.

[0093] The process flow of by-product salt treatment in this embodiment is as follows:

[0094] (1) The saturated brine of the by-product salt is filtered through the membrane filter to form a saturated brine with the following properties: NaCl concentration 300-315 g / l, Ca 2+ and Mg 2+ Concentration ≤10mg / l, SO4 2-Concentration, NaClO3 concentration, suspended matter concentration, TOC concentration ≤ 200 mg / l, pH value 9-10, temperature ≥ 50℃, 0.2MpaG.

[0095] (2) The saturated brine of the by-product salt is filtered through the membrane filter and enters the saturated brine tank 2, and then enters the brine heat exchanger through the brine delivery pump 5 for heat exchange, is heated to between 65 and 80° C., and enters the anode high-level tank of the composite membrane electrolyzer 3. Under the action of gravity, the by-product brine enters the composite membrane electrolyzer 3. The cathode chamber and the anode chamber in the composite membrane electrolyzer 3 are separated by a fluorine-containing fiber composite membrane. Under the action of the fluorine-containing fiber composite membrane and the current, the chloride ions and sodium ions in the anode chamber are separated, and the chloride ions are converted into chlorine gas. The sodium ions and part of the sodium chloride solution pass through the composite membrane into the cathode chamber. In the cathode chamber, the sodium ions combine with the hydroxide ions decomposed by water to form sodium hydroxide, and the hydrogen ions are converted into hydrogen gas.

[0096] (3) Chlorine gas is sent to the chlorine utilization unit 21 through the gas suction and pressurization device 23, and sodium hydroxide (caustic soda) is sent to the caustic soda utilization unit 22.

[0097] (4) In the chlorine utilization unit 21 and the caustic soda utilization unit 22, the by-product salt is regenerated after the caustic soda and chlorine products are used, thereby forming a recycling utilization of the by-product salt resources.

[0098] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A device for resource utilization of by-product salt, characterized in that: The invention comprises a membrane filter, a saturated brine tank and a composite membrane electrolyzer which are connected in sequence according to the process of treating saturated brine of by-product salt, a saturated brine delivery pipeline is arranged between the saturated brine tank and the composite membrane electrolyzer, a saturated brine delivery pump is arranged on the saturated brine delivery pipeline, the composite membrane electrolyzer comprises a number of electrolyzer units, each of which comprises an anode chamber and a cathode chamber, a diaphragm is arranged between the anode chamber and the cathode chamber, and the diaphragm is a fluorine-containing fiber composite membrane; a cathode gas discharge hose and a cathode liquid outlet hose are respectively arranged on the cathode chamber, each The cathode gas discharge hoses in the electrolyzer units are respectively connected to the hydrogen main pipe, the cathode liquid outlet hoses are connected to the single cathode liquid outlet pipes, the single cathode liquid outlet pipes in each electrolyzer unit are connected to the cathode liquid main pipe, and the single cathode liquid outlet pipes are used to adjust the height of the liquid outlet through a single cathode liquid level regulator; the single cathode liquid outlet pipes in each electrolyzer unit are also respectively connected to the waste liquid main pipe through a stop valve; the anode chamber and the cathode chamber are connected around the sealing through a rubber gasket and a rigid flange, and the anode in each electrolyzer unit and the cathode in each electrolyzer unit are respectively connected in series by a conductive device; The fluorine-containing fiber composite membrane is prepared by the following method: (1) Slurry preparation: adding a certain proportion of fluorine-containing material fibers and mineral powder filler materials to an aqueous solution containing sodium chloride and sodium hydroxide, stirring and mixing them thoroughly, and adding a certain proportion of PTFE emulsion to make the fluorine-containing material fibers hydrophilic, and then stirring and mixing the mixed solution at a set mixing temperature through a reactor at a high speed, so that the fluorine-containing material fibers form a network structure in the mixed solution, and the mineral powder filler materials and the aqueous solution of sodium chloride and sodium hydroxide are evenly filled in the grid space of the network structure, thereby forming a uniformly dispersed slurry; (2) Slurry adsorption: The cathode of the electrolytic cell is horizontally contacted with the adsorption slurry or immersed in the adsorption slurry, so that the uniformly dispersed slurry is adsorbed on the cathode of the electrolytic cell, thereby forming a wet film on the surface of the cathode of the electrolytic cell; (3) Drying of wet film: A layer of wet film on the cathode surface of the electrolytic cell is dried at a set drying temperature to form a dry film. The sodium chloride in the wet film is dried to form crystals and is evenly mixed in the mineral powder filling material of the dry film. (4) Sintering into a fluorine-containing material fiber composite membrane: After the wet membrane is dried, it is sintered at a set sintering temperature so that the fluorine-containing material fibers in the dry membrane are firmly bonded together to form a network bonding structure; at the same time, micropores are formed between the mineral powder filling material and the fluorine-containing material fibers, and between the mineral powder filling material particles and the mineral powder filling material particles through the sintering of the dry membrane. The micropores serve as the first microporous channels of the brine on the fluorine-containing material fiber composite membrane during electrolysis. During electrolysis, sodium chloride crystals are dissolved to form the second microporous channels of the brine on the fluorine-containing material fiber composite membrane; Wherein, the fluorine-containing material is a fluorine polymer, and the fluorine-containing material fiber is a fluorine polymer fiber.

2. The device for resource utilization of by-product salt according to claim 1, characterized in that: The anode chamber is respectively provided with an anode liquid inlet hose and an anode liquid outlet hose. The anode liquid inlet hose in each electrolytic cell unit is respectively connected to the anode liquid inlet main pipe, and the anode liquid outlet hose in each electrolytic cell unit is respectively connected to the anode main pipe serving as the anode high-level tank, and a monolithic gas-liquid separator is provided between the anode liquid outlet hose and the anode main pipe.

3. The device for resource utilization of by-product salt according to claim 1, characterized in that: A brine heat exchanger is arranged on the saturated brine delivery pipeline, and the brine heat exchanger is connected to a low-pressure steam pipeline.

4. The device for resource utilization of by-product salt according to claim 1, characterized in that: The preparation of the fluorine-containing material fiber composite membrane includes the following process steps: S1. Preparation of precursor: dissolve sodium chloride and sodium hydroxide in pure water to form a mixed solution of 13% to 15% sodium chloride and 13% to 15% sodium hydroxide by mass ratio, add fluorine-containing material fibers, mineral powder filler materials and pure water in a mass ratio of 1: (2-9): (40-160) to the sodium chloride / sodium hydroxide solution, stir and mix at a high speed of 900 to 5400 r / min in a reactor, and keep the system temperature at 30 to 45°C to uniformly disperse the fluorine-containing material fibers; S2. Slurry preparation: add PTFE emulsion at a mass ratio of 4:1 to fiber under high-speed stirring, continue high-speed stirring, maintain the system temperature at 30-45°C, make the material uniform, and form slurry; S3, membrane adsorption molding: on the cathode of the electrolytic cell, the slurry is adsorbed horizontally or immersed to form a composite membrane; S4, drying: drying temperature 80 ~ 130 ℃; S5, sintering: sintering temperature 120 ~ 345 ℃; Wherein, the mineral powder filling material is one of titanium dioxide powder, zirconium dioxide powder and hydrous magnesium silicate; The fluorine-containing material fiber has a diameter of 2 to 3 μm and a length of 4 to 10 mm; during drying, the temperature is increased step by step from 80°C to 100°C to 120°C; during sintering, the temperature is increased step by step from 120°C to 170°C to 220°C to 270°C to 320°C to 330°C to 340°C to 345°C, and the sintering is performed at 330°C to 345°C for 2 to 3 hours.

5. A process system for resource utilization of by-product salt, characterized in that: The invention comprises a membrane filter, a saturated brine tank, a composite membrane electrolyzer and an electrolysis product utilization unit which are sequentially arranged according to the process flow of treating saturated brine of by-product salt, wherein the electrolysis product utilization unit comprises a chlorine utilization unit and a caustic soda utilization unit, wherein the alkali solution produced by the composite membrane electrolyzer is delivered to the caustic soda utilization unit through a delivery system after the system is powered off, and the chlorine produced by the composite membrane electrolyzer is delivered to the chlorine utilization unit through a gas suction and pressurizing device; wherein the diaphragm used in the composite membrane electrolyzer is a fluorine-containing material fiber composite membrane, and the fluorine-containing material fiber composite membrane is prepared by the following method: (1) Slurry preparation: adding a certain proportion of fluorine-containing material fibers and mineral powder filler materials to an aqueous solution containing sodium chloride and sodium hydroxide, stirring and mixing them thoroughly, and adding a certain proportion of PTFE emulsion to make the fluorine-containing material fibers hydrophilic, and then stirring and mixing the mixed solution at a set mixing temperature through a reactor at a high speed, so that the fluorine-containing material fibers form a network structure in the mixed solution, and the mineral powder filler materials and the aqueous solution of sodium chloride and sodium hydroxide are evenly filled in the grid space of the network structure, thereby forming a uniformly dispersed slurry; (2) Slurry adsorption: The cathode of the electrolytic cell is horizontally contacted with the adsorption slurry or immersed in the adsorption slurry, so that the uniformly dispersed slurry is adsorbed on the cathode of the electrolytic cell, thereby forming a wet film on the surface of the cathode of the electrolytic cell; (3) Drying of wet film: A layer of wet film on the cathode surface of the electrolytic cell is dried at a set drying temperature to form a dry film. The sodium chloride in the wet film is dried to form crystals and is evenly mixed in the mineral powder filling material of the dry film. (4) Sintering into a fluorine-containing material fiber composite membrane: After the wet membrane is dried, it is sintered at a set sintering temperature so that the fluorine-containing material fibers in the dry membrane are firmly bonded together to form a network bonding structure; at the same time, micropores are formed between the mineral powder filling material and the fluorine-containing material fibers, and between the mineral powder filling material particles and the mineral powder filling material particles through the sintering of the dry membrane. The micropores serve as the first microporous channels of the brine on the fluorine-containing material fiber composite membrane during electrolysis. During electrolysis, sodium chloride crystals are dissolved to form the second microporous channels of the brine on the fluorine-containing material fiber composite membrane; Wherein, the fluorine-containing material is a fluorine polymer, and the fluorine-containing material fiber is a fluorine polymer fiber.

6. A process system for resource utilization of by-product salt according to claim 5, characterized in that: A chlorine delivery pipeline is connected between the composite membrane electrolyzer and the chlorine utilization unit, a caustic soda delivery pipeline is connected between the composite membrane electrolyzer and the caustic soda utilization unit, and a cooling circulation loop is connected between the chlorine delivery pipeline and the caustic soda delivery pipeline, the cooling circulation loop exchanges heat with the chlorine delivery pipeline through a chlorine cooler, and the cooling circulation loop exchanges heat with the caustic soda delivery pipeline through a caustic soda cooler.

7. A process system for resource utilization of by-product salt according to claim 5, characterized in that: The caustic soda and chlorine products are continuously used in the electrolysis product utilization unit to regenerate by-product salt.

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