Method and system suitable for producing sodium perchlorate in high-altitude low-pressure low-oxygen environment

Abstract

The invention discloses a method and a system suitable for producing sodium perchlorate in a high-altitude low-pressure low-oxygen environment, which can adapt to different low-pressure low-oxygen environments through three-stage ceramic membrane gradient filtration and electrolytic pressure enhanced oxygen supply without additional auxiliary equipment, and realize the purposes that the yield is greater than or equal to 85%, the product purity is greater than or equal to 99.6%, the chloride content is less than or equal to 0.12%, and the product purity is greater than or equal to 99.6%. The core defects that in the prior art, the high-altitude yield is low, impurity removal is not thorough, and adaptability is poor are effectively overcome. Salt lake potassium and lithium extraction waste tail salt is used as a main raw material, salty mud is recycled to be used as a building material, the mother liquor recycling rate is larger than or equal to 96%, no solid waste or waste water is discharged, tail gas reaches the standard, and the green development requirement is met. And the equipment investment is reduced by 13-15%, the annual maintenance cost is reduced by 29-36%, the energy consumption per ton of products is reduced to 820-845 kWh, and the economical efficiency is outstanding. Core equipment is mature, parameters can be adjusted along with the altitude through a built-in database, high-altitude low-maintenance scenes can be adapted, large-scale production can be achieved, product indexes are superior to industrial standards, and market competitiveness is high.

Description

Technical Field

[0001] This invention relates to the field of sodium perchlorate production technology, and specifically to a method and system for producing sodium perchlorate in high-altitude, low-pressure, and low-oxygen environments. Background Technology

[0002] Sodium perchlorate, as an important inorganic chemical raw material, is widely used in oxidants, electronic materials, and pharmaceutical intermediates. Current sodium perchlorate production mainly uses electrolysis, but the mainstream processes are designed for atmospheric pressure environments in plains areas and cannot be adapted to the special environments of high-altitude regions.

[0003] High-altitude areas are characterized by low pressure, low temperature, and low oxygen. Directly applying the process used in plains areas will lead to three major problems: First, the low oxygen environment reduces the efficiency of anodic oxidation in the electrolytic reaction, decreasing the yield of sodium chlorate to sodium perchlorate by 15%-20%. Second, the low pressure and low temperature make the reaction system unstable, making it difficult for impurity particles such as Mg(OH)2 to settle, easily clogging ceramic membrane filters, and shortening the equipment operating cycle by more than 30%. Third, the traditional process has low raw material utilization, and the high cost of transporting raw materials in high-altitude areas further exacerbates the pressure on production costs.

[0004] The applicant's region has a large amount of waste salt mud (rich in sodium chloride), a byproduct of salt lake production. Sodium chloride, produced by the electrolysis of water, yields sodium chlorate as an intermediate product. Sodium chlorate is an inorganic compound, typically a white or slightly yellow isometric crystal with a salty and cool taste. It is readily soluble in water and slightly soluble in ethanol. It exhibits strong oxidizing properties in acidic solutions and decomposes to produce oxygen above 300°C. Due to its oxidizing properties, it is primarily used in the production of sodium chlorite and potassium perchlorate. Furthermore, China's sodium chlorate exports have increased significantly in recent years, rising from less than 10,000 tons in 2021 to 40,000 tons in 2022. With increasingly stringent environmental regulations in China, downstream water treatment applications are demanding more sodium chlorate, resulting in a supply-demand gap in China and substantial future market growth potential.

[0005] While existing technologies mention preliminary explorations in the production of sodium perchlorate in high-altitude areas, they lack core adaptation technologies designed for specific environments, resulting in problems such as low reaction efficiency, unstable product purity, and insufficient resource utilization. Therefore, this application uses sodium chloride as the main raw material and its intermediate product, sodium chlorate, as an auxiliary material. Through process optimization, it studies a process suitable for sodium perchlorate production in high-altitude areas, producing high-quality sodium perchlorate products. Simultaneously, the intermediate product, sodium chlorate, can be used as a downstream raw material or exported. Summary of the Invention

[0006] Based on the aforementioned technical problems, and addressing the issues of low yield, difficulty in controlling purity, and insufficient resource utilization in the production of sodium perchlorate under high-altitude, low-pressure, low-temperature, and low-oxygen environments, this invention provides a sodium perchlorate production process and system that features localized raw materials, precise adaptation of process parameters, and high recycling rate, thereby achieving efficient industrial-scale production of sodium perchlorate in high-altitude areas.

[0007] This invention protects a method for producing sodium perchlorate in high-altitude, low-pressure, and low-oxygen environments, specifically comprising the following steps: Step 1, Raw material pretreatment: Using sodium chloride, a byproduct of the salt lake, as the main raw material, it is added to the water clarification tank at a mass ratio of sodium chloride to water of 1:2.8~3.2. The mixture is heated to 32~38℃ and stirred to dissolve. Barium chloride and sodium fluoride are added sequentially to remove impurities. After settling and clarification, the primary brine is obtained by primary filtration through a ceramic membrane. The salt mud produced from pretreatment and filtration is dehydrated by pressure filtration until the moisture content is ≤30%, and then used as a building material raw material. Furthermore, in step 1, the sodium chloride by-product from the salt lake comes from the waste tailings after potassium and lithium extraction from the local salt lake. After simple screening to remove large impurities, it can be used directly without additional purification, which greatly reduces the cost of raw materials and transportation energy consumption. The purity of the sodium chloride is ≥95%.

[0008] Further, in step 1, barium chloride at 0.4%~0.6% of the mass of sodium chloride is added sequentially, and the mixture is stirred for 25~35 min. Then, sodium fluoride at 0.2%~0.4% of the mass of sodium chloride is added and stirred for 15~25 min to remove impurities. After standing and clarifying for 1.5~2.5 h, the mixture is filtered through a primary ceramic membrane to obtain primary brine. The primary ceramic membrane has a pore size of 0.1~1 μm, an initial pressure of 0.2~0.3 MPa, and the pressure is adjusted to 0.25~0.35 MPa when the membrane flux decreases by 8~12%. The filtration rate is 1.5~2.0 m / h, and the turbidity of the primary brine after filtration through the primary ceramic membrane is ≤8 NTU.

[0009] Step 2, Electrolytic Oxidation: The primary brine is filtered through a two-stage ceramic membrane and then fed into a specially designed electrolytic cell; the pressure in the electrolytic cell is controlled at 0.8~1.0 MPa, the temperature at 80~90℃, and direct current is applied with a current density controlled at 1900~2300 A / m. 2 The oxygen is supplied naturally by the air and oxygen dissolution is enhanced by pressure regulation. The crude sodium perchlorate solution is generated by electrolysis for 3.5~5 hours. Furthermore, in step 2, the pore size of the secondary ceramic membrane is 50~60nm, and gradient pressure control is adopted: the initial pressure is 0.3~0.4MPa, and the pressure is adjusted to 0.35~0.45MPa when the membrane flux decreases by 8~12%. The turbidity of the brine after filtration by the secondary ceramic membrane is ≤5NTU.

[0010] Furthermore, in step 2, the specially designed electrolytic cell uses titanium alloy electrodes, and the anode coating is an iridium-ruthenium dioxide composite coating with an iridium to ruthenium mass ratio of 2~4:1. The effective electrolysis area to brine treatment capacity ratio is 1m². 2 :180~220L / h, increasing electrode area to enhance reaction efficiency.

[0011] Step 3, intelligent membrane separation and purification: the tail gas generated by electrolysis is recovered, and the crude sodium perchlorate solution is filtered through a three-stage ceramic membrane to remove impurities and residual Cl⁻; Furthermore, in step 3, the pore size of the tertiary ceramic membrane is 30~40nm, the pressure is 0.4~0.5MPa, and the filtration rate is 1.0~1.5m / h; through the gradient pore size design from the second stage of 50~60nm to the third stage of 30~40nm, it is ensured that the Cl⁻ content after treatment is ≤0.15%.

[0012] Step 4, High-efficiency crystallization: The purified sodium perchlorate solution is fed into a low-temperature vacuum evaporator and concentrated to a concentration of 55-65% at 55-65℃ and 0.07-0.09MPa. The concentrated solution is crystallized using a gradient cooling method, and the sodium perchlorate product is obtained by centrifugation and hot air drying. The mother liquor from centrifugation is returned to the electrolytic oxidation for recycling. Further, in step 4, the gradient cooling crystallization is first cooled to 28-32℃ at a rate of 4-6℃ / h and held for 0.8-1.2h, then cooled to 8-12℃ at a rate of 1.5-2.5℃ / h and held for 3.5-4.5h; the centrifugal speed is 2800-3200r / min; the hot air drying is carried out at a crystal to hot air mass flow rate ratio of 1:7-9, the drying temperature is 75-85℃, the drying time is 0.8-1.2h, and the hot air velocity is 12-18m / s.

[0013] This invention also protects the above-mentioned system for the efficient and environmentally friendly production of sodium perchlorate in high-altitude, low-pressure, and low-oxygen environments, including a raw material pretreatment unit, an electrolytic oxidation unit, a purification unit, a crystallization and drying unit, and a resource recycling unit. The raw material pretreatment unit comprises a water distribution and clarification tank 1 and a primary ceramic membrane filter 2; the inlet of the water distribution and clarification tank 1 is connected to a water source pipeline, and the feed inlet of the water distribution and clarification tank 1 is connected to a sodium chloride silo, a barium chloride silo, and a sodium fluoride silo, respectively; the outlet of the water distribution and clarification tank 1 is connected to the inlet of the primary ceramic membrane filter 2. The electrolytic oxidation unit includes a secondary ceramic membrane filter 3 and a specially designed electrolytic cell 4; the outlet of the primary ceramic membrane filter 2 is connected to the inlet of the secondary ceramic membrane filter 3; the outlet of the secondary ceramic membrane filter 3 is connected to the inlet of the specially designed electrolytic cell 4. The purification unit includes a three-stage ceramic membrane filter 5; the outlet of the specially designed electrolytic cell 4 is connected to the three-stage ceramic membrane filter 5; The crystallization and drying unit includes a low-temperature vacuum evaporator 6, a crystallizer 7, a centrifuge 8, and an airflow dryer 9; the outlet of the three-stage ceramic membrane filter 5 is connected to the low-temperature vacuum evaporator 6, the outlet of the low-temperature vacuum evaporator 6 is connected to the crystallizer 7, the outlet of the crystallizer 7 is connected to the centrifuge 8, and the crystal outlet of the centrifuge 8 is connected to the airflow dryer 9. The resource recycling unit includes a mother liquor recovery tank 10. The mother liquor outlet of the centrifuge 8 is connected to the mother liquor recovery tank 10, and the outlet of the mother liquor recovery tank 10 is connected to the circulation inlet of the special electrolytic cell 4.

[0014] Furthermore, the water distribution and clarification tank 1 is equipped with a stirrer and a temperature sensor; the primary ceramic membrane filter 2 and the secondary ceramic membrane filter 3 are equipped with pressure sensors and automatic regulating valves; the tertiary ceramic membrane filter 5 is equipped with a pressure controller; the low-temperature vacuum evaporator 6 is equipped with a vacuum controller; the crystallizer 7 is equipped with a gradient cooling system; and the airflow dryer 9 is equipped with a hot air circulation system.

[0015] Furthermore, the specially designed electrolytic cell 4 is equipped with an oxygen concentration sensor, a pressure controller, and titanium alloy electrodes; the pressure controller has a database corresponding to altitude and parameters, which is applicable to different altitudes, and the parameters are set directly by referring to the database when the production line is deployed.

[0016] Compared with existing technologies, the present invention has the following beneficial effects: This invention utilizes a three-stage ceramic membrane gradient filtration system and enhanced oxygen supply through electrolysis pressure, eliminating the need for additional auxiliary equipment. It is adaptable to various low-pressure, low-oxygen environments, achieving a yield of ≥85%, product purity of ≥99.6%, and chloride content of ≤0.12%. This overcomes the core shortcomings of existing technologies, such as low yield at high altitudes, incomplete impurity removal, and poor adaptability. Using waste salt from potassium and lithium extraction in salt lakes as the main raw material, no additional purification is required. The dehydrated salt mud is used as a building material raw material, with a mother liquor recycling rate of ≥96%. The entire process achieves resource utilization of mother liquor and salt mud, with no solid waste or wastewater discharge, and the exhaust gas meets standards, aligning with green development needs and solving the problems of resource waste and high environmental pressure associated with existing processes. Equipment investment is reduced by 13-15%, and annual maintenance costs are reduced by 29-36%. Energy consumption per ton of product is reduced to 820-845 kWh, a reduction of over 32% compared to traditional processes, demonstrating significant economic advantages. The core equipment is mature, and the parameters can be flexibly adjusted according to altitude through the built-in database. There is no need to set up a separate production line. The process is adapted to high-altitude and low-maintenance scenarios, and it can be mass-produced. The product indicators are better than industry standards, and it has strong market competitiveness. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a system flowchart of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] A system suitable for producing sodium perchlorate in high-altitude, low-pressure, and low-oxygen environments includes a raw material pretreatment unit, an electrolytic oxidation unit, a purification unit, a crystallization and drying unit, and a resource recycling unit. The raw material pretreatment unit consists of a water distribution and clarification tank 1 and a primary ceramic membrane filter 2; the inlet of the water distribution and clarification tank 1 is connected to the water source pipeline, the feed port of the water distribution and clarification tank 1 is connected to the sodium chloride silo, barium chloride silo, and sodium fluoride silo respectively; the outlet of the water distribution and clarification tank 1 is connected to the inlet of the primary ceramic membrane filter 2. The electrolytic oxidation unit includes a two-stage ceramic membrane filter 3 and a specially designed electrolytic cell 4; the outlet of the first-stage ceramic membrane filter 2 is connected to the inlet of the second-stage ceramic membrane filter 3; the outlet of the second-stage ceramic membrane filter 3 is connected to the inlet of the specially designed electrolytic cell 4. The purification unit includes a three-stage ceramic membrane filter 5; the outlet of the specially designed electrolytic cell 4 is connected to the three-stage ceramic membrane filter 5; The crystallization and drying unit includes a low-temperature vacuum evaporator 6, a crystallizer 7, a centrifuge 8, and an airflow dryer 9; the outlet of the three-stage ceramic membrane filter 5 is connected to the low-temperature vacuum evaporator 6, the outlet of the low-temperature vacuum evaporator 6 is connected to the crystallizer 7, the outlet of the crystallizer 7 is connected to the centrifuge 8, and the crystal outlet of the centrifuge 8 is connected to the airflow dryer 9. The resource recycling unit includes a mother liquor recovery tank 10, the mother liquor outlet of the centrifuge 8 is connected to the mother liquor recovery tank 10, and the outlet of the mother liquor recovery tank 10 is connected to the circulation inlet of the special electrolytic cell 4.

[0020] The system includes: a water clarification tank 1 equipped with a stirrer and temperature sensor; primary ceramic membrane filters 2 and 3 equipped with pressure sensors and automatic regulating valves; a tertiary ceramic membrane filter 5 equipped with a pressure controller; a low-temperature vacuum evaporator 6 equipped with a vacuum controller; a crystallizer 7 equipped with a gradient cooling system; and an airflow dryer 9 equipped with a hot air circulation system. A specially designed electrolytic cell 4 is equipped with an oxygen concentration sensor, a pressure controller, and titanium alloy electrodes. The pressure controller contains a database corresponding to altitude and parameters, making it suitable for different altitudes. When the production line is deployed, parameters can be directly set by referring to the database.

[0021] A method for producing sodium perchlorate suitable for high-altitude, low-pressure, and low-oxygen environments includes the following steps: Step 1, Raw material pretreatment: Using sodium chloride, a byproduct of the salt lake, as the main raw material, it is added to the water preparation and clarification tank at a mass ratio of sodium chloride to water of 1:2.8~3.2. The mixture is heated to 32~38℃ and stirred to dissolve. Barium chloride and sodium fluoride are added sequentially to remove impurities. After settling and clarification, the primary brine is obtained by primary filtration through a ceramic membrane. The salt mud produced from pretreatment and filtration is dehydrated by pressure filtration until the moisture content is ≤30%, and then used as a building material raw material. Sodium chloride, a byproduct of salt lake extraction, comes from waste salt tailings after potassium and lithium extraction from local salt lakes. After simple sieving to remove large impurities, it is used directly without additional purification, significantly reducing raw material costs and transportation energy consumption. The purity of the sodium chloride is ≥95%. 0.4%–0.6% (by weight of sodium chloride) of barium chloride is added sequentially, and the mixture is stirred for 25–35 minutes. Then, 0.2%–0.4% (by weight of sodium chloride) of sodium fluoride is added, and the mixture is stirred for 15–25 minutes to remove impurities. After standing and clarifying for 1.5–2.5 hours, the mixture is filtered through a primary ceramic membrane to obtain primary brine. The primary ceramic membrane has a pore size of 0.1–1 μm, an initial pressure of 0.2–0.3 MPa, and is adjusted to 0.25–0.35 MPa when the membrane flux decreases by 8–12%. The filtration rate is 1.5–2.0 m / h, and the turbidity of the primary brine after primary ceramic membrane filtration is ≤8 NTU.

[0022] Step 2, Electrolytic Oxidation: The primary brine is filtered through a two-stage ceramic membrane and then fed into a specially designed electrolytic cell; the pressure in the electrolytic cell is controlled at 0.8~1.0 MPa, the temperature at 80~90℃, and direct current is applied with a current density controlled at 1900~2300 A / m. 2 The oxygen is supplied naturally by the air and oxygen dissolution is enhanced by pressure regulation. The crude sodium perchlorate solution is generated by electrolysis for 3.5~5 hours. The secondary ceramic membrane has a pore size of 50-60 nm and is controlled by gradient pressure: initial pressure 0.3-0.4 MPa, adjusted to 0.35-0.45 MPa when membrane flux decreases by 8-12%, resulting in a brine turbidity ≤5 NTU after filtration through the secondary ceramic membrane. The specially designed electrolytic cell uses titanium alloy electrodes, with an anode coating of iridium-ruthenium dioxide composite coating at a mass ratio of 2-4:1. The effective electrolysis area to brine treatment capacity ratio is 1 m² / m³. 2 :180~220L / h, increasing electrode area to enhance reaction efficiency.

[0023] Step 3, intelligent membrane separation and purification: the tail gas generated by electrolysis is recovered, and the crude sodium perchlorate solution is filtered through a three-stage ceramic membrane to remove impurities and residual Cl⁻; The tertiary ceramic membrane has a pore size of 30~40nm, a pressure of 0.4~0.5MPa, and a filtration rate of 1.0~1.5m / h. Through the gradient pore size design from the secondary 50~60nm to the tertiary 30~40nm, the Cl⁻ content after treatment is ensured to be ≤0.15%.

[0024] Step 4, High-efficiency crystallization: The purified sodium perchlorate solution is sent to a low-temperature vacuum evaporator and concentrated to a concentration of 55-65% at 55-65℃ and 0.07-0.09MPa. The concentrate is crystallized using a gradient cooling method, and the sodium perchlorate product is obtained by centrifugation and hot air drying. The mother liquor from centrifugation is returned to the electrolytic oxidation cycle for reuse. The gradient cooling method involves first cooling the crystals at a rate of 4-6℃ / h to 28-32℃ and holding them at that temperature for 0.8-1.2h, then cooling them at a rate of 1.5-2.5℃ / h to 8-12℃ and holding them at that temperature for 3.5-4.5h; centrifugation speed is 2800-3200r / min; hot air drying is carried out at a crystal to hot air mass flow rate ratio of 1:7-9, drying temperature is 75-85℃, drying time is 0.8-1.2h, and hot air velocity is 12-18m / s.

[0025] The above system and method produce sodium perchlorate. The specific implementation process, parameter control and result verification of the present invention can be repeated by those skilled in the art based on the following content.

[0026] Example 1 Example 1: Using the database of altitude and parameters in the specially designed electrolytic cell pressure controller, the altitude was adjusted to 2500m, the air pressure to be about 75kPa, and the average annual temperature to be 6℃, and the following scheme was implemented.

[0027] I. Raw Material Preparation and System Setup 1. Raw material preparation The selected materials include sodium chloride (95.5% purity) from the salt lake by-products, sourced from potassium extraction tailings of Chaka Salt Lake in Qinghai; local groundwater with a total hardness of 120 mg / L; industrial-grade barium chloride (98.2% purity); and industrial-grade sodium fluoride (97.3% purity).

[0028] 2. System Settings (1) Water distribution and clarification tank (effective volume 5m³) 3 It features a paddle mixer and a PT100 temperature sensor. (2) Primary ceramic membrane filter (membrane pore size 0.5μm, membrane area 2m²) 2 (with pressure transmitter and automatic regulating valve) (3) Secondary ceramic membrane filter (membrane pore size 55nm, membrane area 3m²) 2 ); (4) Specially designed electrolytic cell (titanium alloy electrodes, effective area 5m²) 2 (Anodized coating Ir:Ru=3:1). (5) Three-stage ceramic membrane filter (membrane pore size 35nm, membrane area 2m²) 2 ) (6) Low-temperature vacuum evaporator (evaporation area 10m²) 2 ); (7) Crystallizer (with PLC gradient cooling system); (8) Centrifuge (horizontal screw, processing capacity 1t / h); (9) Airflow dryer (air volume 500m³) 3 / h); (10) Mother liquor recovery tank (volume 2m³) 3 ).

[0029] II. Specific Implementation Steps 1. Raw material pretreatment (1) Add 1000 kg of salt lake by-product sodium chloride that has been screened to remove impurities >5 mm to the water clarification tank, add 3000 kg of groundwater at a mass ratio of 1:3, turn on the stirrer, rotate at 200 r / min, heat the liquid to 35°C, and stir to dissolve for 30 min.

[0030] (2) Add 5 kg of barium chloride at 0.5% of the mass of sodium chloride, stir for 30 min, and remove SO4. 2 ⁻; Then add 3 kg of sodium fluoride at 0.3% of the mass of sodium chloride, stir for 20 minutes to remove Ca. 2 ⁺、Mg 2 ⁺.

[0031] (3) Turn off the stirrer and let it stand for 2 hours to clarify. Pump the supernatant into a primary ceramic membrane filter (membrane pore size 0.5 μm). Set the initial pressure to 0.25 MPa. When the membrane flux drops by 10%, automatically adjust to 0.3 MPa. The filtration rate is 1.8 m / h to obtain primary brine. After testing, SO42- 2 ⁻=0.006%, Ca 2 ⁺+Mg 2 ⁺=0.002%, turbidity 6.2 NTU.

[0032] (4) The salt mud produced by pretreatment is about 21 kg. It is dewatered to a moisture content of 27% by plate and frame filter press and sent to the local building materials factory as brick making auxiliary material. The primary ceramic membrane filter is backwashed regularly, once every 8 hours, with a regeneration rate of ≥95%.

[0033] 2. Electrolytic oxidation (1) The primary brine is fed into the secondary ceramic membrane filter. The initial pressure is set to 0.35 MPa. When the membrane flux monitoring shows a 10% decrease, the pressure is adjusted to 0.4 MPa. The filtration rate is 1.3 m / h. The turbidity of the brine after filtration is 3.5 NTU, removing fine colloidal impurities.

[0034] (2) Pump the brine filtered through the secondary ceramic membrane into a special electrolytic cell.

[0035] (3) Turn on the booster pump to stabilize the electrolytic cell pressure at 0.85 MPa and maintain the cell temperature at 85°C; apply DC power and adjust the current density to 2100 A / m. 2 Electrolysis for 4 hours produces crude sodium perchlorate solution, which, upon testing, contains 18.8% NaClO4 and 0.52% Cl⁻.

[0036] 3. Intelligent membrane separation and purification (1) Recovery of tail gas generated by electrolysis.

[0037] (2) The crude sodium perchlorate solution was fed into a three-stage ceramic membrane filter with a membrane pore size of 35 nm, a control pressure of 0.45 MPa, and a filtration rate of 1.2 m / h. The membrane pore size intercepted Cl⁻ and trace impurities, and the Cl⁻ content was reduced to 0.11% after treatment.

[0038] 4. High-efficiency crystallization (1) The purified sodium perchlorate solution was sent to a low-temperature vacuum evaporator, and the temperature was controlled at 60℃ and the vacuum degree at 0.08MPa. The solution was concentrated to 60% in 3.5 hours.

[0039] (2) The concentrate is pumped into the crystallizer and the gradient cooling method is adopted: first, it is cooled to 30°C at a rate of 5°C / h and kept at the temperature for 1h, then cooled to 10°C at a rate of 2°C / h and kept at the temperature for 4h to form uniform crystals with a crystal particle size of 0.7~1.0mm.

[0040] (3) The crystallization liquid was fed into a centrifuge, the speed was controlled at 3000 r / min, and centrifuged for 15 min to separate wet crystals with a water content of 4.7% and 860 kg of mother liquor.

[0041] (4) The wet crystals are sent into the airflow dryer, and hot air at 80°C is introduced at a mass flow rate of 1:8 between crystals and hot air at a speed of 15 m / s. The dryer is dried for 1 hour to obtain sodium perchlorate product.

[0042] (5) The mother liquor is sent to the mother liquor recovery tank for recycling in the electrolytic oxidation step. The recycling volume accounts for 35% of the total water distribution, and the recycling rate is 96.5%.

[0043] III. Implementation Results A single batch of sodium perchlorate produced 174.2 kg of finished product. The test indicators were: purity 99.7%, chloride content (calculated as Cl) 0.11%, moisture 0.07%, sulfate content (calculated as SO4) 0.005%; sodium perchlorate conversion rate 87.1%; sodium chloride consumption per ton of product 1.16 tons; energy consumption 835 kWh.

[0044] Example 2 Example 2: Using the database of altitude and parameters in the specially designed electrolytic cell pressure controller, the altitude was adjusted to 3000m, the air pressure to be about 70kPa, and the average annual temperature to be 4℃, and the following scheme was implemented.

[0045] I. Raw Material Preparation and System Setup Same as Example 1 II. Specific Implementation Steps Based on Example 1, the following parameters were adjusted to address the low-pressure, low-oxygen environment caused by increased altitude: The electrolytic cell pressure was increased to 0.9 MPa, and the electrolysis time was extended to 4.5 hours. The initial pressure of the primary ceramic membrane filter is 0.28 MPa, which is adjusted to 0.35 MPa after the flux decreases by 10%. The three-stage ceramic membrane filter has a pressure of 0.48 MPa and a filtration rate of 1.1 m / h. The mother liquor circulation volume accounts for 40% of the total water distribution volume.

[0046] III. Implementation Results A single batch of sodium perchlorate product yielded 177.5 kg. The test results showed a purity of 99.8%, chloride content of 0.10%, and moisture content of 0.06%. The sodium perchlorate conversion rate was 88.7%, the sodium chloride consumption per ton of product was 1.14 tons, the energy consumption was 820 kWh, and the Cl⁻ removal rate of the three-stage ceramic membrane reached 99.2%.

[0047] Example 3 Example 3: Using the database of altitude and parameters in the specially designed electrolytic cell pressure controller, the altitude was adjusted to 3500m, the air pressure to be about 65kPa, and the average annual temperature to be 2℃, and the following scheme was implemented.

[0048] I. Raw Material Preparation and System Setup Same as Example 1 II. Specific Implementation Steps Based on Example 1, the following parameters were adjusted to address the low-pressure, low-oxygen environment caused by increased altitude: The electrolysis pressure was increased to 1.0 MPa, the temperature was controlled at 88℃, and the current density was 2200 A / m. 2 Electrolysis time: 5 hours; The initial pressure of the primary ceramic membrane filter is 0.3 MPa, and it is adjusted to 0.35 MPa after the flux decreases by 10%. The initial pressure of the secondary ceramic membrane filter is 0.4 MPa, and it is adjusted to 0.45 MPa after the flux decreases by 10%. The three-stage ceramic membrane filter has a pore size of 32nm, a pressure of 0.5MPa, and a filtration rate of 1.0m / h. Concentration temperature 65℃, vacuum degree 0.09MPa.

[0049] III. Implementation Results A single batch produced 170.3 kg of sodium perchlorate. The test results showed a purity of 99.6%, chloride content of 0.12%, and moisture content of 0.08%. The sodium perchlorate conversion rate was 85.1%, and the sodium chloride consumption per ton of product was 1.18 tons, with an energy consumption of 845 kWh. Even at a high altitude and low pressure environment of 3500m, the yield was ≥85%. The three-stage ceramic membrane filtration exhibited excellent stability, with the membrane flux decreasing by only 5% after 72 hours of continuous operation and fully recovering after backwashing.

[0050] Comparative Example 1 The scheme of Embodiment 1 of the present invention (altitude 2500m) is compared with the traditional process.

[0051] I. Traditional Plains Craftsmanship 1. Raw material pretreatment: Sodium chloride:water = 1:3, temperature 35℃, barium chloride 0.5%, sodium fluoride 0.3% (same as Example 1, but without altitude adaptation and extended settling time), quartz sand filtration, filter media particle size 0.8mm, filtration rate 2.0m / h; 2. Electrolytic oxidation: The ceramic membrane pressure is fixed at 0.4 MPa, the oxygen generator supplements oxygen to 25%, the electrolysis pressure is 0.6 MPa, the temperature is 95℃, and the current density is 2000 A / m³. 2 Electrolysis for 4 hours; 3. Separation and purification: Secondary ceramic membrane pressure 0.5MPa, ion exchange resin: crude liquor = 1:5; 4. Crystallization and drying: Concentration temperature 80℃, cooling rate fixed at 5℃ / h, centrifugation speed 3000r / min, drying temperature 90℃.

[0052] II. Experimental Results The comparison revealed that the oxygen-enriched generator had insufficient oxygen replenishment efficiency under low-pressure conditions, and electrolytic oxidation was still incomplete; the membrane filtration pressure was not matched with the high-altitude environment, leading to clogging; the energy consumption of high-temperature concentration was not reduced; and the addition of new equipment significantly increased investment and maintenance costs.

[0053] Table 1. Comparison of parameters between Comparative Example 1 and Example 1 index Comparative Example 1 Example 1 Improvement of differences Yield (%) 72.5 87.1 +14.6% Product purity (%) 99.0 99.7 +0.7% Chloride content (%) 0.21 0.11 -0.10% Moisture (%) 0.20 0.07 -0.13% Energy consumption per ton of product (kWh) 1180 835 -29.2% Comparative Example 2 The scheme of Embodiment 2 of the present invention (altitude 3000m) is compared with the traditional process.

[0054] I. Traditional Plains Craftsmanship 1. Raw material pretreatment: Sodium chloride:water = 1:3, temperature 35℃, barium chloride 0.5%, sodium fluoride 0.3%, quartz sand filtration, filter media particle size 0.8mm, filtration rate 2.0m / h; 2. Electrolytic oxidation: The ceramic membrane pressure is fixed at 0.4 MPa, the oxygen generator supplements oxygen to 26%, the electrolysis pressure is 0.6 MPa, the temperature is 95℃, and the current density is 2000 A / m³. 2 Electrolysis for 4.5 hours (only extended time, no other altitude adaptation); 3. Separation and purification: Two-stage ceramic membrane pressure 0.5MPa, ion exchange column, resin: crude liquor = 1:5; 4. Crystallization and drying: Concentration temperature 80℃, cooling rate fixed at 5℃ / h, centrifugation speed 3000r / min, drying temperature 90℃.

[0055] II. Experimental Results The comparison revealed that the impact of low-pressure and low-oxygen environments on the process intensified with increased altitude: the oxygen replenishment efficiency of the oxygen generator further decreased, and even with extended electrolysis time, it was still unable to meet the oxygen demand for the reaction, resulting in incomplete electrolytic oxidation; the excessively rapid cooling rate of the crystals led to impurity encapsulation, and although the ion exchange column could partially remove impurities, the purity was still lower than that of the adjusted scheme; the frequency of membrane blockage increased, leading to higher maintenance costs; energy consumption was not effectively controlled, and the disadvantage of high equipment investment costs became more pronounced.

[0056] Table 2 Comparison of parameters between Comparative Example 2 and Example 2 index Comparative Example 2 Example 2 Improvement of differences Yield (%) 69.8 88.7 +18.9% Product purity (%) 98.8 99.8 +1.0% Chloride content (%) 0.24 0.10 -0.14% Moisture (%) 0.23 0.06 -0.17% Energy consumption per ton of product (kWh) 1250 820 -34.4% Comparative Example 3 The scheme of Embodiment 3 of the present invention (altitude 3500m) is compared with the traditional process.

[0057] I. Traditional Plains Craftsmanship 1. Raw material pretreatment: Sodium chloride:water = 1:3, temperature 35℃, barium chloride 0.5%, sodium fluoride 0.3%, quartz sand filtration, filter media particle size 0.8mm, filtration rate 2.0m / h; 2. Electrolytic oxidation: The ceramic membrane pressure is fixed at 0.4 MPa, the oxygen generator supplements oxygen to 28%, the electrolysis pressure is 0.6 MPa, the temperature is 95℃, and the current density is 2000 A / m³. 2 Electrolysis for 5 hours (no other altitude adaptation adjustments); 3. Separation and purification: Two-stage ceramic membrane pressure 0.5MPa, ion exchange column, resin: crude liquor = 1:5; 4. Crystallization and drying: Concentration temperature 80℃, cooling rate fixed at 5℃ / h, centrifugation speed 3000r / min, drying temperature 90℃.

[0058] II. Experimental Results Comparative analysis revealed fatal flaws in this traditional process at an altitude of 3500m, under low pressure and low oxygen conditions: the oxygen generator cannot effectively replenish oxygen concentration under low pressure, causing a sharp drop in catalyst activity and a significant decline in electrolysis efficiency; low pressure lowers the boiling point of the solution, leading to violent boiling during high-temperature concentration and severe material loss; the membrane filtration system frequently clogs, resulting in a surge in maintenance frequency; although the ion exchange column can partially remove chlorides, the overall product purity still does not meet standards; and the high investment and maintenance costs contrast sharply with the low yield, making it completely unsuitable for industrialization.

[0059] Table 3 Comparison of parameters between Comparative Example 3 and Example 3 index Comparative Example 3 Example 3 Improvement of differences Yield (%) 65.2 85.1 +19.9% Product purity (%) 98.5 99.6 +1.1% Chloride content (%) 0.27 0.12 -0.15% Moisture (%) 0.25 0.08 -0.17% Energy consumption per ton of product (kWh) 1320 845 -36.0% In summary, traditional plain processes, lacking flexible adjustment of process parameters and equipment adaptation design for high-altitude, low-pressure, and low-oxygen environments, still suffer from low yields (65.2-72.5%), high energy consumption (1180-1320 kWh / ton), and high maintenance costs. In contrast, the present invention achieves a yield of ≥85%, purity of ≥99.6%, and a reduction in energy consumption of ≥34% without employing high-cost equipment. Furthermore, it reduces equipment investment costs by 13-15% and annual maintenance costs by 32-36%, completely resolving the core pain point of traditional processes that rely on auxiliary equipment and cannot adapt to high-altitude environments, while significantly improving industrialization economics.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for producing sodium perchlorate suitable for use in high altitude low pressure low oxygen environments, characterized in that, Specifically comprising the following steps: Step 1, raw material pretreatment: taking the by-product sodium chloride from salt lake as the main raw material, adding water into the water clarification tank according to the mass ratio of sodium chloride to water = 1:2.8~3.2, stirring and dissolving under the temperature of 32~38℃, adding barium chloride and sodium fluoride in sequence to remove impurities, clarifying and filtering through the first ceramic membrane to obtain primary brine; the salt mud produced by pretreatment and filtration is dewatered by pressure filtration to a water content of ≤30%, and then used as a building material after dewatering; Step 2, electrolytic oxidation: the primary brine is filtered by a secondary ceramic membrane and then sent to a special electrolytic tank; the pressure of the electrolytic tank is controlled at 0.8-1.0 MPa, the temperature is controlled at 80-90℃, direct current is passed in and the current density is controlled at 1900-2300 A / m 2 , air is naturally supplied and oxygen dissolution is strengthened by pressure regulation, and the sodium perchlorate crude liquid is generated after electrolysis for 3.5-5 h; Step 3, intelligent membrane separation and purification: recovering the tail gas produced by electrolysis, removing impurities and residual Cl⁻ from the sodium perchlorate crude liquid through three-stage ceramic membrane filtration; Step 4, efficient crystallization: sending the purified sodium perchlorate solution into a low-temperature vacuum evaporator, concentrating to a concentration of 55~65% under the conditions of 55~65℃ and 0.07~0.09MPa, crystallizing the concentrated liquid by gradient cooling method, and obtaining the finished product of sodium perchlorate through centrifugal separation and hot air drying; the mother liquor from centrifugal separation is returned to the electrolytic oxidation cycle for reuse.

2. The method of claim 1, wherein, In step 1, the by-product sodium chloride from salt lake is obtained after the extraction of potassium and lithium from the local salt lake, and after simple screening to remove large impurities, it can be directly used without additional purification, which greatly reduces the cost of raw materials and transportation energy consumption, and the purity of sodium chloride is ≥95%.

3. The method of claim 2, wherein, In step 1, 0.4%~0.6% of barium chloride based on the mass of sodium chloride is added in sequence, stirring for 25~35min, and then 0.2%~0.4% of sodium fluoride based on the mass of sodium chloride is added, stirring for 15~25min to remove impurities; after clarifying for 1.5~2.5h, the primary brine is filtered through the first ceramic membrane; the pore size of the first ceramic membrane is 0.1~1μm, the initial pressure is 0.2~0.3MPa, when the membrane flux decreases by 8~12%, the pressure is adjusted to 0.25~0.35MPa, the filtration rate is 1.5~2.0m / h, and the turbidity of the primary brine after the first ceramic membrane filtration is ≤8NTU.

4. The method of claim 1, wherein, In step 2, the pore size of the second ceramic membrane is 50~60nm, and the gradient pressure control is adopted: the initial pressure is 0.3~0.4MPa, when the membrane flux decreases by 8~12%, the pressure is adjusted to 0.35~0.45MPa, and the turbidity of the brine after the second ceramic membrane filtration is ≤5NTU.

5. The method of claim 1, wherein, In step 2, the special electrolytic cell adopts titanium alloy electrode, the anode coating is iridium ruthenium dioxide composite coating with mass ratio of iridium to ruthenium being 2~4:1, and the ratio of effective electrolysis area to salt water treatment capacity is 1m 2 :180~220L / h.

6. The method of claim 1, wherein, In step 3, the pore size of the third ceramic membrane is 30~40nm, the pressure is 0.4~0.5MPa, and the filtration rate is 1.0~1.5m / h.

7. The method of claim 1, wherein, In step 4, the gradient cooling method is used to cool the concentrated liquid to 28~32℃ at a rate of 4~6℃ / h, and then to 8~12℃ at a rate of 1.5~2.5℃ / h, and the cooling is maintained for 0.8~1.2h and 3.5~4.5h respectively; the centrifugal speed is 2800~3200r / min; the hot air drying is carried out at a temperature of 75~85℃ for 0.8~1.2h, and the mass flow ratio of crystal to hot air is 1:7~9, the hot air speed is 12~18m / s.

8. A system suitable for efficient and environmentally friendly production of sodium perchlorate in a high-altitude low-pressure low-oxygen environment, characterized by, The system is suitable for the method of any one of claims 1-7, and comprises a raw material pretreatment unit, an electrolytic oxidation unit, a purification unit, a crystallization and drying unit, and a resource recycling unit. The raw material pretreatment unit comprises a water distribution clarifier (1) and a first ceramic membrane filter (2); the water inlet of the water distribution clarifier (1) is connected with a water source pipeline, and the feeding port of the water distribution clarifier (1) is respectively connected with a sodium chloride bin, a barium chloride bin and a sodium fluoride bin; the outlet of the water distribution clarifier (1) is connected with the inlet of the first ceramic membrane filter (2); The electrolytic oxidation unit comprises a second ceramic membrane filter (3) and a special electrolytic tank (4); the outlet of the first ceramic membrane filter (2) is connected with the inlet of the second ceramic membrane filter (3); the outlet of the second ceramic membrane filter (3) is connected with the inlet of the special electrolytic tank (4); The purification unit comprises a third ceramic membrane filter (5); the liquid outlet of the special electrolytic tank (4) is connected with the third ceramic membrane filter (5); The crystallization and drying unit comprises a low-temperature vacuum evaporator (6), a crystallizer (7), a centrifugal machine (8) and an air flow dryer (9); the outlet of the third ceramic membrane filter (5) is connected with the low-temperature vacuum evaporator (6), the outlet of the low-temperature vacuum evaporator (6) is connected with the crystallizer (7), the outlet of the crystallizer (7) is connected with the centrifugal machine (8), and the crystal outlet of the centrifugal machine (8) is connected with the air flow dryer (9); The resource recycling unit comprises a mother liquor recovery tank (10); the mother liquor outlet of the centrifugal machine (8) is connected with the mother liquor recovery tank (10), and the outlet of the mother liquor recovery tank (10) is connected with the circulating water inlet of the special electrolytic tank (4).

9. The system of claim 8, wherein, The water distribution clarifier (1) is provided with a stirrer and a temperature sensor; the first ceramic membrane filter (2) and the second ceramic membrane filter (3) are provided with a pressure sensor and an automatic adjusting valve; the third ceramic membrane filter (5) is provided with a pressure controller; the low-temperature vacuum evaporator (6) is provided with a vacuum controller; the crystallizer (7) is provided with a gradient cooling system; and the air flow dryer (9) is provided with a hot air circulation system.

10. The system of claim 8, wherein, The special electrolytic tank (4) is provided with an oxygen concentration sensor, a pressure controller and a titanium alloy electrode; the pressure controller is provided with a corresponding database of altitudes and parameters, and is suitable for different altitudes; when the production line is placed on the ground, the parameters can be directly set by referring to the database.

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