阅读说明：本技术 一种钒铬钛废盐回用于氯碱的方法 (Method for reusing vanadium-chromium-titanium waste salt in chlor-alkali ) 是由 蒲荣辉 刘军 张芋 谢明辉 尹文刚 石玉英 于 2021-09-24 设计创作，主要内容包括：本发明公开了一种钒铬钛废盐回用于氯碱的方法,包含钒铬钛废盐精制系统除去钒铬钛、重金属离子、颗粒杂质以及降低氯酸根,以及利用氯碱盐水精制系统除去钙镁铁、其他金属离子、颗粒杂质、游离氯、氯酸根和硫酸根。本发明将钒铬钛废盐水、固体废盐中影响较大的钒铬钛等重金属离子和氯酸根离子集中在钒铬钛废盐精制系统中同步进行除去,工业化回用于氯碱化工的生产,实现废盐资源化利用,解决固体废盐处置困难的问题。(The invention discloses a method for reusing vanadium-chromium-titanium waste salt in chlor-alkali, which comprises a vanadium-chromium-titanium waste salt refining system for removing vanadium-chromium-titanium, heavy metal ions and particle impurities and reducing chlorate, and a chlor-alkali brine refining system for removing calcium-magnesium-iron, other metal ions, particle impurities, free chlorine, chlorate and sulfate. According to the method, heavy metal ions such as vanadium, chromium and titanium and chlorate ions which have great influence in the vanadium, chromium and titanium waste salt water and the solid waste salt are concentrated in the vanadium, chromium and titanium waste salt refining system to be removed synchronously, and are industrially reused for the production of chlor-alkali chemical industry, so that the resource utilization of the waste salt is realized, and the problem of difficult disposal of the solid waste salt is solved.)

1. The method for reusing vanadium, chromium and titanium waste salt as chlor-alkali is characterized by comprising the following steps of:

(1) introducing solid waste salt and high-salinity wastewater into a vanadium-chromium-titanium waste salt refining system, filtering by a two-step refining membrane to remove vanadium, chromium and titanium, heavy metal ions and particle impurities, and catalytically decomposing to reduce chlorate to obtain qualified brine, and introducing the qualified brine into a chlor-alkali brine refining system;

(2) in the chlor-alkali refining system, firstly removing calcium-magnesium-iron and other metal ions capable of precipitating by a two-alkali method from qualified brine by a two-alkali membrane filtration method, removing particle impurities and free chlorine to obtain primary refined brine, further adsorbing the metal ions by chelating resin to obtain secondary refined brine conforming to chlor-alkali chemical ionic membrane caustic soda, and feeding the secondary refined brine into an electrolytic bath for electrolysis; part of the electrolyzed light brine enters a chlorate decomposer, chlorate radicals are further reduced by a high-temperature hydrochloric acid method, part of the dechlorinated light brine enters a membrane method denitration device, and sulfate radicals are reduced by a sodium filter membrane method to obtain low-nitrate brine; the low-nitrate brine is mixed with qualified brine produced by waste salt to redissolve the industrial salt.

2. The method for recycling waste vanadium chromium titanium salt for chlor-alkali as claimed in claim 1, characterized in that said system for refining waste vanadium chromium titanium salt comprises the following steps and control method:

s1 water distribution: stirring and mixing the vanadium-chromium-titanium high-salinity wastewater, the salt dissolving water and the primary and secondary salt sludge press-filtered water in a water distribution barrel;

s2 pre-decomposition: adding hydrochloric acid into the prepared salt-containing wastewater, and controlling the pH value to be 6.5-7.5 to decompose part of components in the salt-containing wastewater;

s3 salt dissolving: feeding the pre-decomposed salt-containing wastewater into a salt dissolving pool, and dissolving solid waste salt to obtain saturated crude salt water;

s4 first-stage refining reaction: adding hydrochloric acid and a refining agent AB into the saturated crude brine in sequence, controlling the pH value to be 1.5-2.5, and feeding the brine added with the refining agent AB into a primary reaction tank; adding a pH stabilizer into the first-stage reaction tank, controlling the pH value to be 2.5-5.0, and maintaining the reaction time to be not less than 30 minutes;

s5 first-stage refining filtration: feeding the primary refined reaction liquid into a primary refined filter for filtering to obtain primary refined filtrate; the primary refining filtration adopts an organic membrane micro-pressure terminal filtration process, the membrane aperture is 300-;

and (3) mixing of S6 decomposer: adding hydrochloric acid and chlorate decomposer into the first-stage refined filtrate, and controlling pH value to be 1.5-2.5; the mixed brine enters a chlorate decomposer;

s7 chlorate decomposition: heating in chlorate decomposer with steam, maintaining chlorate decomposition temperature at 80-95 deg.C, and decomposing time no less than 5 min to obtain first-grade refined perchlorate salt water;

s8 secondary refining reaction: continuously adding a pH stabilizer into the primary refined perchlorate brine, controlling the pH value to be 7.0-9.0, and maintaining the reaction time to be not less than 30 minutes;

s9 secondary refining and filtering: feeding the secondary refined reaction liquid into a secondary refined filter for filtering to obtain qualified brine, and reusing the qualified brine in a chlor-alkali brine refining system for further removing other impurities; the secondary refining filtration adopts inorganic membrane belt pressure cross flow filtration technology, and the membrane aperture is 40-50 nm; the salt mud formed by filtering enters a secondary salt mud for filter pressing;

s10 pressure filtration of salty mud: and respectively carrying out filter pressing on the primary refined salt mud and the secondary refined salt mud, wherein the salt mud forms solid waste residues, and filter pressing water returns to the water mixing barrel.

3. The method for recycling waste vanadium chromium titanium salts as claimed in claim 2, wherein the chlorate decomposer is at least one of sodium thiosulfate, formaldehyde, acetaldehyde and glyoxal; the refining agent AB is at least one of ferric nitrate, ferrous chloride, ferric trichloride, ferric sulfate, ferrous sulfate, ferric tribromide, ferrous bromide and ferric perchlorate; the pH stabilizer comprises the following components in parts by mass: 5-7 parts of methyl alcohol amine, 1-3 parts of sodium hydroxide and 1-3 parts of sodium bicarbonate.

4. The method for recycling the vanadium-chromium-titanium waste salt as the chlor-alkali as claimed in claim 1, wherein the qualified salt contains sodium chloride 290-310g/L, vanadium-chromium-titanium not more than 0.01mg/L, other heavy metal ions not more than 0.02mg/L and chlorate not more than 5 g/L.

Technical Field

The invention belongs to the technical field of waste water and waste salt treatment, and particularly relates to a method for reusing vanadium-chromium-titanium waste salt in chlor-alkali.

Background

The reduction of the source of waste resources is promoted, and the production in a clean and environment-friendly way is a necessary trend for enterprises to realize sustainable development. During the production of titanium (sponge titanium and chloride titanium white), a large amount of high-salinity wastewater mainly containing sodium chloride is generated. Tail gas treatment sections such as molten salt chlorination, titanium white chloride, titanium tetrachloride refining and low temperature chlorination, by water washing and alkali washing (sodium hydroxide), generate a large amount of waste hydrochloric acid, sodium hypochlorite and sodium chloride waste water; such as molten salt medium sodium chloride added in the molten salt chlorination process, is discharged with the slag to form salt-containing slag.

In recent years, titanium production enterprises are introduced into a wastewater treatment system and a waste residue treatment system in an exploration mode by combining the process characteristics of the titanium production enterprises, and partial vanadium, chromium and titanium resources are recycled. The two treatment systems can form high-salinity wastewater with different components, and solid waste salt (NaCl) is formed through evaporation, centrifugal separation and drying and recycled in the molten salt chlorination furnace for recycling or export sale. In actual operation, however, the high-salinity wastewater resource is difficult to recycle, so that the green environmental development of the waste resources of titanium enterprises is greatly restricted; specifically, the method comprises the following steps:

1. the solid waste salt has low sodium chloride content (less than or equal to 93 percent), high content of harmful impurities, more components and complex existing forms. In the high-salinity wastewater after resource recovery, metal impurities with complex forms, such as vanadium, chromium, titanium and the like still exist, and the content of the metal impurities reaches 2-5 mg/L; and ions such as calcium, magnesium, iron, manganese, lead, zinc, silicon and the like in the wastewater enter the concentrated solution to enter the high-salinity wastewater along with membrane separation; the content of sulfate radical and chlorate radical in the high-salt waste water is up to 7-13 g/L. The waste salt water formed by the waste water treatment system and the waste residue treatment system has different components, solid waste salt prepared from high-salinity waste water containing high impurities is yellow, the content of sodium chloride is low (less than or equal to 93 percent), the content of harmful impurities is high, the components are more, and the existing forms are complex.

2. Disposal of the excess solid waste salt is difficult. Due to high harmful impurities and low grade, the method greatly limits the use approaches of external sales. If all solid waste salts are adopted and recycled into the molten salt chlorination furnace, the furnace condition of the chlorination furnace is unstable, and the product quality of the refined titanium tetrachloride is influenced. Therefore, only part of solid waste salt can be recycled by the molten salt chlorination furnace, and industrial salt is still added in the molten salt chlorination. The solid waste salt is derived from waste mother liquor and reaction residues of industrial production and still belongs to solid waste; the redundant solid waste salt is easy to dissolve in water due to sodium chloride, and cannot be buried according to an industrial solid waste management method, so that surface water, underground water and soil are polluted, and the ecological environment is damaged; and the occupied area of on-site stacking and storage is larger.

3. The treatment cost of ton salt of the wastewater zero discharge treatment process adopted by titanium production enterprises is higher.

4. The country and the place have made certain restricted discharge requirements for the discharge of the salt-containing wastewater, and the supervision and treatment of the illegal behaviors of the salt-containing wastewater and the solid wastes are increased. Therefore, how to realize low-cost utilization and zero emission of high-salinity wastewater is a 'neck clamp' problem facing the development of titanium enterprises and to be solved urgently.

The application of the waste salt in the chlor-alkali industry is a recommended optimal waste salt resource utilization mode. In recent years, related technical specifications or management guidelines, such as technical specification of recycling of waste salt in chemical and related industries for chlor-alkali industry in Shandong province, have been successively issued by countries and places aiming at recycling or harmless treatment of waste salt in chemical industries (such as hydrazine hydrate and pesticides). However, the disposal of the waste salt containing vanadium, chromium and titanium produced by titanium production enterprises (titanium sponge and titanium dioxide by chlorination process) still has no relevant technical specifications. The main reasons are that the waste salt produced in the titanium production and the chemical industry has different components: the waste salt produced in the chemical industry is mainly organic matter and is treated by advanced oxidation, high-temperature melting oxidation or high-temperature incineration; the waste salt produced by titanium enterprises is mainly composed of metal cations with different valence states and anions such as sulfate radical, chlorate radical and the like, and the impurities just have important influence on the ion membrane electrolysis production process of chlor-alkali chemical industry. For example, various impurity ions form crystals in the ion membrane to block a water and sodium migration channel in the ion membrane, so that the voltage of an electrolytic cell of the ion membrane is increased, the current efficiency is reduced, and even the ion membrane is damaged to cause safety accidents. Therefore, in order to enable the indexes of the waste brine entering the chlor-alkali production system to meet the requirements of the ion membrane electrolytic cell, the technical treatment difficulty is high, the disposal cost is high, and most chlor-alkali enterprises are difficult to accept.

In the existing methods, for example, a method for treating waste brine containing vanadium, chromium and titanium (application publication number CN112499827A), a method for treating waste brine containing vanadium, chromium and titanium in a pilot plant stage is summarized, but how to industrially reuse vanadium, chromium and titanium waste salt for production of chlor-alkali chemical industry and how to solve a method for removing other impurities in a process of recycling chlor-alkali are not further summarized.

Disclosure of Invention

Aiming at the defects, the invention provides a method for recycling vanadium-chromium-titanium waste salt into chlor-alkali, which recycles waste salt water and solid waste salt produced by a titanium enterprise into the production of chlor-alkali chemical industry in an industrialized way, realizes the resource utilization of the waste salt of the titanium enterprise and solves the problem of difficult disposal of the solid waste salt.

In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problems is as follows: aiming at the characteristics of impurity components in waste salt produced by titanium enterprises, the industrial utilization method of removing impurities and purifying step by step is provided. A vanadium-chromium-titanium waste salt refining system is adopted to remove vanadium-chromium-titanium, heavy metal ions and particle impurities and reduce chlorate; and removing calcium, magnesium, iron, other metal ions, particle impurities, free chlorine, chlorate and sulfate radicals by using a chlor-alkali brine refining system. The method comprises the following steps:

(1) vanadium chromium titanium waste salt refining system: high-salinity wastewater, salty mud filter-pressing water and other salt dissolving water produced by titanium enterprises are distributed by a water distribution barrel to form salt dissolving water. Adding hydrochloric acid, performing pre-decomposition reaction, then dissolving solid waste salt in a salt dissolving tank to obtain vanadium-chromium-titanium saturated brine, adding hydrochloric acid and a refining agent AB, mixing, then feeding into a primary refining reaction tank, adding a pH stabilizer in the primary refining reaction tank to maintain a low pH value, and stirring and mixing for a certain time to complete primary refining reaction. The brine after the first-stage refining reaction is filtered by a first-stage refining filter, and then enters a chlorate decomposer after hydrochloric acid and a chlorate decomposition catalyst are added. In the chlorate decomposer, the reaction temperature is maintained by steam heating, and the chlorate is decomposed. And (3) allowing the primary refined brine with low chlorate to enter a secondary refining reaction tank, continuously adding a pH stabilizer in the secondary refining reaction tank to maintain a relatively high pH value, and mixing for a certain time to complete the secondary refining reaction. And filtering the brine subjected to the secondary refining reaction by using a secondary refining filter to obtain qualified salt water, and allowing the salt water to enter a chlor-alkali brine refining system for continuously removing other impurities.

(2) Chlorine alkali refining system: firstly, removing calcium, magnesium and iron and other metal ions which can be precipitated by a two-alkali membrane filtration method (caustic soda and soda ash are used as refining agents), removing particle impurities and free chlorine to obtain primary refined brine, further adsorbing the metal ions by chelating resin to obtain secondary refined brine which meets the requirement of chlor-alkali chemical ionic membrane caustic soda, and feeding the secondary refined brine into an electrolytic cell for electrolysis. And (3) allowing a part of the electrolyzed light brine to enter a chlorate decomposer, further reducing chlorate radicals by a high-temperature hydrochloric acid method, allowing a part of the dechlorinated light brine to enter a membrane-method denitration device, and reducing sulfate radicals by a sodium filter membrane method to obtain low-nitrate brine. The low-nitrate brine is mixed with qualified brine produced by waste salt to redissolve the industrial salt.

Further, the vanadium-chromium-titanium waste salt refining system specifically comprises the following steps and a control method:

s1 water distribution: stirring and mixing high-salinity wastewater (containing 100 sodium chloride and 150g/L) of vanadium, chromium and titanium, salt dissolving water and primary and secondary salt mud press-filtered water in a water distribution barrel;

s2 pre-decomposition: adding hydrochloric acid into the prepared salt-containing wastewater, and controlling the pH value to be 6.5-7.5 to decompose part of components in the salt-containing wastewater;

s3 salt dissolving: the pre-decomposed salt-containing wastewater enters a salt dissolving pool to dissolve solid waste salt, so as to obtain saturated crude salt water (containing sodium chloride 290 and 310 g/L);

s4 first-stage refining reaction: adding hydrochloric acid and a refining agent AB into the saturated crude brine in sequence, controlling the pH value to be 1.5-2.5, and feeding the brine added with the refining agent AB into a primary reaction tank; adding a pH stabilizer into the first-stage reaction tank, controlling the pH value to be 2.5-5.0, and maintaining the reaction time to be not less than 30 minutes;

s5 first-stage refining filtration: feeding the primary refined reaction liquid into a primary refined filter for filtering to obtain primary refined filtrate; the primary refining filtration adopts an organic membrane micro-pressure terminal filtration process, the membrane aperture is 300-;

and (3) mixing of S6 decomposer: adding hydrochloric acid and chlorate decomposer into the first-stage refined filtrate, and controlling pH value to be 1.5-2.5; the mixed brine enters a chlorate decomposer;

s7 chlorate decomposition: heating in chlorate decomposer with steam, maintaining chlorate decomposition temperature at 80-95 deg.C, and decomposing time no less than 5 min to obtain first-grade refined low chlorate salt water;

s8 secondary refining reaction: continuously adding a pH stabilizer into the primary refined low chlorate salt brine, controlling the pH value to be 7.0-9.0, and maintaining the reaction time to be not less than 30 minutes;

s9 secondary refining and filtering: feeding the secondary refined reaction liquid into a secondary refined filter for filtering to obtain qualified brine, and reusing the qualified brine in a chlor-alkali brine refining system for further removing other impurities; the secondary refining filtration adopts inorganic membrane pressure cross flow filtration technology, and the membrane aperture is 40-50 nm. The salt mud formed by filtering enters a secondary salt mud for filter pressing;

s10 pressure filtration of salty mud: and respectively carrying out filter pressing on the primary refined salt mud and the secondary refined salt mud, wherein the salt mud forms solid waste residues, and filter pressing water returns to the water mixing barrel.

Further, the vanadium, chromium and titanium are removed by adopting a two-step method, namely, in the process of converting the pH value from low to high, high-valence ions are converted into low-valence ions or are flocculated, precipitated and filtered at the low pH value by adding a refining agent AB and a pH stabilizing agent; then, the flocculated hydroxide precipitate is filtered to further remove the water under neutral or weak alkaline. The chlorate decomposition adopts a high-temperature hydrochloric acid method with chlorate decomposer.

Further, the refining agent AB is at least one of ferric nitrate, ferrous chloride, ferric trichloride, ferric sulfate, ferrous sulfate, ferric tribromide, ferrous bromide and ferric perchlorate.

Further, the pH stabilizer comprises the following components in parts by mass: 5-7 parts of methyl alcohol amine, 1-3 parts of sodium hydroxide and 1-3 parts of sodium bicarbonate.

Further, the chlorate decomposer is at least one of sodium thiosulfate, formaldehyde, acetaldehyde and glyoxal.

Further, the sodium chloride 290-310g/L, the vanadium, chromium and titanium are respectively less than or equal to 0.01mg/L, other heavy metal ions are less than or equal to 0.02mg/L, and chlorate is less than or equal to 5g/L in the qualified salt.

Further, a two-stage filtration mode with different apertures is adopted, the first-stage filtration adopts an organic membrane micro-pressure terminal filtration process, and the membrane aperture is 300-400 nm; the secondary filtration adopts an inorganic membrane pressure cross flow filtration process, the filtration pressure is 200-300Kpa, and the membrane aperture is 40-50 nm. Therefore, the refining agent AB still remained in the secondary reaction liquid can be ensured to play a role in flocculation, and the full secondary refining reaction and the more reliable indexes of qualified saline water after secondary filtration can also be ensured.

In summary, the invention has the following advantages:

1. the industrial utilization method of step-by-step impurity removal and purification is adopted, the chlor-alkali brine refining system is used for removing impurities, and an independent vanadium-chromium-titanium waste salt refining system is used for treating heavy metal ions such as vanadium, chromium, titanium and the like and chlorate with great influence. The production cost of applying the waste salt of the titanium enterprise to the chlor-alkali is reduced.

2. The method for removing the heavy metals such as vanadium, chromium, titanium and the like by two steps is adopted, the heavy metals such as vanadium, chromium, titanium and the like are removed more thoroughly, and the vanadium, chromium and titanium in the treated brine are respectively less than or equal to 0.01 mg/L. The heavy metal index is less than or equal to 0.02mg/L (note: the index does not contain calcium, magnesium and iron).

3. The removal of chlorate is more complete. Chlorate decomposer is added into the waste salt refining system, the decomposition rate of chlorate is more than or equal to 85 percent, chlorate in the brine returned to the chlor-alkali brine refining system is less than or equal to 5g/L, and the load of chlorate in the chlor-alkali brine refining system can not be increased. The residual decomposer is removed under the action of trace titanium dioxide in the secondary refining reaction and is not carried into a subsequent system.

4. The waste salt water and the solid waste salt can be treated simultaneously. Although the components of the waste brine or the solid waste salt generated by the two ways (wastewater treatment and waste residue treatment) of the titanium enterprise are different, the device can still realize the production modes of the waste brine, the waste brine + the solid waste salt, the production water + the solid waste salt, and has the advantage of production organization.

5. The waste salt water and the solid waste salt produced by the titanium enterprise can be reused for the industrial production of the chlor-alkali chemical industry, the sodium chloride recycled by the waste salt can account for 13 percent of the total amount of the sodium chloride consumed by the chlor-alkali, the resource utilization of the waste salt of the titanium enterprise is realized, and the problem of difficult disposal of the solid waste salt of the titanium enterprise is solved.

6. Heavy metal ions such as vanadium, chromium, titanium and the like and chlorate ions which have great influence are concentrated in a vanadium, chromium and titanium waste salt refining system and are synchronously removed; calcium, magnesium, iron ions and other metal ions which can be removed by a two-alkali membrane filtration method (caustic soda and soda ash are used as refining agents) are placed in primary and secondary brine refining in a chlor-alkali brine refining system, and sulfate ion removal is placed in the chlor-alkali brine refining system. The impurity removal distribution is reasonably carried out, so that the production cost is reduced, and the impurity removal load of a subsequent chlor-alkali brine refining system is reduced. Chlorate is removed by high-temperature hydrochloric acid decomposition method with chlorate decomposer. Thus, the decomposition rate of chlorate can be improved, and the consumption of hydrochloric acid, steam and a decomposer can be reduced. The residual decomposing agent is removed under the action of trace titanium dioxide in the secondary refining reaction, and cannot be brought into a subsequent system.

Drawings

FIG. 1 is a flow chart of a method for recycling vanadium, chromium and titanium waste salt for chlor-alkali;

FIG. 2 is a process flow diagram of a vanadium-chromium-titanium waste salt refining system.

In the figure, 1, water is distributed; 2. pre-decomposition; 3. dissolving salt; 4. primary refining reaction; 5. primary refining and filtering; 6. mixing the decomposers; 7. decomposing chlorate; 8. performing secondary refining reaction; 9. secondary refining and filtering; 10. primary salt mud is subjected to pressure filtration; 11 and carrying out pressure filtration on the secondary salt mud.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

In one embodiment of the present invention, as shown in fig. 1, there is provided a method for recycling waste vanadium-chromium-titanium salt for chlor-alkali, comprising the following steps:

(1) introducing solid waste salt and high-salinity wastewater into a vanadium-chromium-titanium waste salt refining system, filtering by a two-step refining membrane to remove vanadium, chromium and titanium, heavy metal ions and particle impurities, and then catalytically decomposing to reduce the content of chlorate to obtain qualified brine;

(2) dissolving the qualified salt water and the low-nitrate salt water obtained in the step (1) into the industrial salt, removing calcium, magnesium and iron and other metal ions capable of being precipitated by a two-alkali membrane filtration method (using caustic soda and soda ash as refining agents), removing particle impurities and free chlorine to obtain primary refined salt water, further adsorbing the metal ions by chelating resin to obtain secondary refined salt water conforming to the chlor-alkali chemical ionic membrane caustic soda, and feeding the secondary refined salt water into an electrolytic tank for electrolysis. And (3) allowing a part of the electrolyzed light brine to enter a chlorate decomposer, further reducing chlorate radicals by a high-temperature hydrochloric acid method, allowing a part of the dechlorinated light brine to enter a membrane-method denitration device, and reducing sulfate radicals by a sodium filter membrane method to obtain low-nitrate brine. The low-nitrate brine is mixed with qualified brine produced by waste salt to redissolve the industrial salt.

As shown in FIG. 2, the steps and control method for the process of the vanadium-chromium-titanium waste salt refining system are as follows:

s1 water distribution: stirring and mixing high-salinity wastewater (containing 100 sodium chloride and 150g/L) of vanadium, chromium and titanium, salt dissolving water and primary and secondary salt mud press-filtered water in a water distribution barrel;

s2 pre-decomposition: adding hydrochloric acid into the prepared salt-containing wastewater, and controlling the pH value to be 6.5-7.5 to decompose part of components in the salt-containing wastewater;

s3 salt dissolving: the pre-decomposed salt-containing wastewater enters a salt dissolving pool to dissolve solid waste salt, so as to obtain saturated crude salt water (containing sodium chloride 290 and 310 g/L);

s4 first-stage refining reaction: adding hydrochloric acid and a refining agent AB into the saturated crude brine in sequence, controlling the pH value to be 1.5-2.5, and feeding the brine added with the refining agent AB into a first-stage reaction tank. Adding a pH stabilizer into the first-stage reaction tank, controlling the pH value to be 2.5-5.0, and maintaining the reaction time to be not less than 30 minutes;

s5 first-stage refining filtration: and (4) feeding the primary refined reaction liquid into a primary refined filter for filtering to obtain a primary refined filtrate. The primary refining filtration adopts an organic membrane micro-pressure terminal filtration process, the membrane aperture is 300-;

and (3) mixing of S6 decomposer: adding hydrochloric acid and chlorate decomposer into the first-stage refined filtrate, and controlling pH value to be 1.5-2.5; the mixed brine enters a chlorate decomposer;

s7 chlorate decomposition: heating in chlorate decomposer with steam, maintaining chlorate decomposition temperature at 80-95 deg.C, and decomposing time no less than 5 min to obtain first-grade refined perchlorate salt water;

s8 secondary refining reaction: continuously adding a pH stabilizer into the primary refined perchlorate brine, controlling the pH value to be 7.0-9.0, and maintaining the reaction time to be not less than 30 minutes;

s9 secondary refining and filtering: feeding the secondary refined reaction liquid into a secondary refined filter for filtering to obtain qualified brine, and reusing the qualified brine in a chlor-alkali brine refining system for further removing other impurities; the secondary refining filtration adopts inorganic membrane pressure cross flow filtration technology, and the membrane aperture is 40-50 nm. The salt mud formed by filtering enters a secondary salt mud for filter pressing;

s10 pressure filtration of salty mud: and respectively carrying out filter pressing on the primary refined salt mud and the secondary refined salt mud, wherein the salt mud forms solid waste residues, and filter pressing water returns to the water mixing barrel.

While the present invention has been described in detail with reference to the specific embodiments thereof, it should not be construed as limited by the scope of the present patent. Various modifications and changes may be made by those skilled in the art without inventive step within the scope of the appended claims.