CN101235510A - Method for removing SO4(2-) ion in ionic film electrolysis sodium hydroxide light salt water - Google Patents

Abstract

The invention discloses a method for removing SO42-ion in caustic soda weak brine through electrolyzing by ionic film, after the chlorination of the weak brine which is generated from electrolysis in an electrolysis bath, excepting the sharing diffluence of the weak brine is used as salt-dissolving water to prepare the brine in soda production by the ammonia-soda process, the other weak brine is reused for preparing crude salt in the process, wherein the insufficient is supplemented by water, after refining, removing impurities by chelating resin, then obtaining the brine with Na2SO4 <= 5g/L, then which is transferred to an ionic film electrolysis bath and being electrolyzed, the brine volume which is transferred to the soda production by the ammonia-soda process and used as the salt-dissolving water is transferred to the ionic film electrolysis bath and being controlled by the equilibrium of SO42-concentration in the brine of the ionic film electrolysis bath after removing impurities by the chelating resin. The method has the advantages that the environment pollution and environment damage which are caused by adopting the barium salt method to remove sulfate in current ionic film caustic soda industry are eliminated, the proceeding of the produce is guaranteed, the organic combination of the ionic film caustic soda and the soda production proceeded by the ammonia-soda process are realized, the method has the advantages of realizing aims of resource sharing and dominance mutual complementing, and saving cost.

Description

SO in the electrolysis with ion-exchange film caustic soda light salt brine fine 42-The ion removal methods

Technical field

The interior SO of high concentration sulphate light salt brine that the present invention relates to electrolyze table salt in a kind of ion film caustic soda industry and produce ₄ ^2-The ionic removal methods.

Background technology

Current ionic membrane legal system caustic soda technology, be to adopt the method for electrolytic brine in ion-exchange membrane electrolyzer to produce caustic soda, the light salt brine that produces after the electrolysis then circulates again after dechlorination and is used for the brinish preparation, and the brine quality that enters electrolyzer is the key of this technology, its life-span, bath voltage and current efficiency and quality product important influence to ionic membrane, therefore must make with extra care going into groove salt solution, to remove harmful ion wherein, steps such as the many employingization salt of brinish preparation, salt refining, resin removal of impurities make.SO wherein ₄ ^2-After ion enters electrolyzer, can in film, form Na ₂SO ₄Crystalline deposit descends current efficiency, increases power consumption, increases production cost.Serious also can make film forming physical damage, makes film can't repair and scrap.For guaranteeing the work-ing life of ionic membrane, must guarantee the 5O in the salt solution ₄ ^2-Concentration is with Na ₂SO ₄Meter maintains in the 5g/L.SO in the salt solution ₄ ^2-Foreign ion, main source have two aspects: (1) from crude salt with Na ₂SO ₄, Mg ₂SO ₄Form directly bring into, (2) add Na in the salt refining process ₂SO ₃Remove ClO and generate new SO ₄ ^2-, owing to SO in electrolytic process ₄ ^2-Ion does not decompose, thereby adopts light salt brine circulation after the electrolysis to be used for brinish and produce and will produce salt solution SO ₄ ^2-Continuous cumulative rises of ion and cause SO in the salt solution ₄ ^2-Therefore ionic concn too high this phenomenon of ordinary production that influences that becomes need be used for circulation the electrolysis light salt brine that salt solution produces and remove SO ₄ ^2-Ion is so that carrying out smoothly of producing.Light salt brine removes SO at present ₄ ^2-The most frequently used method of ion is a chemical method, comprises calcium salt method and barium salt process, also useful physical method one membrane filtration, but still be in the development phase, and cost an arm and a leg, can't be applied to large-scale Chemical Manufacture.And employing calcium salt method treatment S O ₄ ^2-, its effect is difficult for satisfying the requirement of ion film caustic soda to brine quality, so ion film caustic soda removes SO ₄ ^2-Many employings is barium salt process at present, and its technical process has two kinds usually: (1) will all contain high density SO ₄ ^2-Being used for of light salt brine salt, heavy saturated after, totally add BaCL again ₂Generate BaSO ₄Precipitation is removed part SO ₄ ^2-, make Na in the saturated brine ₂SO ₄≤ 7g/L; (2) will contain high density SO ₄ ^2-The part (as account for global cycle light salt brine amount 1/3) of light salt brine remove SO ₄ ^2-(control is with Na ₂SO ₄The meter≤5g/L) after, being used for salt also will make Na in the saturated brine at last again ₂SO ₄≤ 7g/L, but all there is very big defective in these two kinds of methods: and (1) adds BaCL ₂After, though generate BaSO ₄Precipitation, but Ba is always arranged in the solution ²⁺Exist, cause the brinish secondary pollution, and if make SO ₄ ^2-Concentration is with Na ₂SO ₄Meter is about 5g/L, then Ba ²⁺About about 0.2-0.3mg/L, and Ba ²⁺Existence have a strong impact on life-span of ionic membrane equally; (2) because BaSO ₄Settling velocity is slow, and suspended substance exceeds standard in the salt solution than being easier to cause, and also film is caused damage; The adding of barium ion has simultaneously also caused the harm of heavy metal barium to environment.And the employing barium salt process is removed the SO in the light salt brine ₄ ^2-Ion need adopt BaSO ₄The expense of equipment such as precipitation settling tank, bariumchloride liquid Preparation tank, bariumchloride liquid header tank, bariumchloride liquid lift pump and capital construction has increased the working cost of producing.In order to save water resources, people adopted extra large hydratable salt during refined brine in the production of current solvay soda process soda ash was prepared simultaneously, because the Ca in the seawater ²⁺, Mg ²⁺Content is higher, and people need be with Ca ²⁺, Mg ²⁺Be used further to producing of soda ash after removing, increased the production complexity and removed Ca ²⁺, Mg ²⁺Raw material such as sodium carbonate amount.

Summary of the invention

Technical problem to be solved by this invention has provided a kind of barium salt process that do not adopt both can reduce SO in the light salt brine ₄ ^2-Ion is used to produce SO in the qualified brinish electrolysis with ion-exchange film caustic soda light salt brine fine ₄ ^2-The ion removal methods has not only avoided the employing barium salt process to remove SO ₄ ^2-Ion pair is produced the influence brought, and the heavy metal barium that causes of the barium ion that adds reduced productive expense to the harm of environment, and can reduce the salt refining required materials of soda ash in producing.

For solving the problems of the technologies described above, technical scheme of the present invention is: SO in the electrolysis with ion-exchange film caustic soda light salt brine fine ₄ ^2-The ion removal methods, the light salt brine that electrolytic tank electrolysis produces is after dechlorination is handled, removing the part shunting is used for the production of solvay soda process soda ash and carries out the salt solution preparation as changing salt solution, all the other light salt brine reuse salt operations prepare crude brine, the insufficient section make up water makes after refining, resin removal of impurities then and contains Na ₂SO ₄The salt solution of≤5g/L is transported to ion-exchange membrane electrolyzer and carries out electrolysis.The light salt brine that electrolysis produces in the ion film caustic soda preparation is through after the dechlorination, removing the part shunting is used for the production of solvay soda process soda ash and carries out the salt solution preparation as changing salt solution, the change salt operation that the rest part light salt brine is back to use the electrolysis with ion-exchange film caustic soda prepares crude brine, and employing in shortage does not contain or contain micro-SO ₄ ^2-Assorted water of ionic or ordinary production water replenish hybridization salt and prepare crude brine, thereby reduce SO by the consumption that reduces electrolysis with ion-exchange film caustic soda salt reuse light salt brine like this ₄ ^2-Content, both reduced SO in the whole totalization salt solution ₄ ^2-Ionic concentration makes SO in the salt solution of preparation ₄ ^2-Ionic concn reaches produces needed standard, i.e. SO in the salt solution ₄ ^2-Concentration is with Na ₂SO ₄Meter maintains in the 5g/L.

Being transported to the production of solvay soda process soda ash as changing brinish light salt brine amount, is by to being transported to the SO in the ion-exchange membrane electrolyzer salt solution after the resin removal of impurities ₄ ^2-The control of concentration is adjusted.Be respectively applied for the light salt brine amount that ionic membrane legal system caustic soda and solvay soda process soda ash production salt are used, can be by adopting to count SO in the salt solution that is transported to ion-exchange membrane electrolyzer after the fat removal of impurities through chelating in the ionic membrane legal system production of caustic soda ₄ ^2-Concentration content is the reference mark, guarantees to be transported to the interior SO of salt solution of ion-exchange membrane electrolyzer ₄ ^2-Concentration content meets the standard of production, both SO ₄ ^2-Concentration is with Na ₂SO ₄Meter≤5g/L determines to prepare with make up water hybridization salt the light salt brine amount of crude brine down, after returning the light salt brine amount, the counterion membrane electrolyser determines again that shunting deammoniation alkaline process soda ash production process is as changing brinish light salt brine flow, behind the light salt brine consumption of control ionic membrane legal system caustic soda salt, insufficient part can adopt water of productive use to replenish.

Light salt brine SO ₄ ^2-Concentration is with Na ₂SO ₄Meter 7.5-9g/L is by closing SO in the salt solution that is transported to ion-exchange membrane electrolyzer after several fat removal of impurities to stinging in the ionic membrane legal system production of caustic soda ₄ ^2-The control of concentration content, the light salt brine total amount that electrolysis produces relatively shunting be transported to the volume ratio of the light salt brine amount that solvay soda process soda ash produces can be 1: 0.15-1: 0.25, even reach about 1: 0.35, be diverted to the soda ash production process as change that the brinish light salt brine adopts and the change brine volume of replenishing than 1: 15-1: prepare refined brine between 25, though this can make SO in the soda ash refined brine ₄ ^2-Concentration will increase to some extent, but because the high density SO that the ion film caustic soda preparation produces ₄ ^2-In the light salt brine with Na ₂SO ₄Meter concentration is 7.5-9g/L, and amount ratio is lower, so after increasing this part light salt brine, SO in the refined brine ₄ ^2-The concentration increasing amount is extremely low, and is also lower to the influence that solvay soda process soda ash is produced; We can say the influence of producing little.

Adopt Ca in the light salt brine ²⁺+ Mg ²⁺≤ 30 μ g/L, it is far below Ca in the seawater ²⁺, Mg ²⁺Content, and contain the about 200g/l of NaCL, be higher than NaCL concentration in the seawater far away, like this production of solvay soda process soda ash adopt add light salt brine salt after, Ca in the salt solution in soda ash is produced ²⁺+ Mg ²⁺Total ionic content adopts the content in the salt solution of extra large hydratable salt to reduce greatly more merely, and this has also reduced finishing agent such as Na that impurity such as calcium, magnesium are removed in required being used to of salt refining ₂CO ₃Consumption.

Be used for light salt brine that ion film caustic soda preparation crude brine produces and adopt with make up water hybridization salt and produce crude brine, also can adopt and replenish ordinary production water salt.Do not contain or contain micro-SO as adopting ₄ ^2-Assorted water of ionic or ordinary production water replenish hybridization salt and prepare crude brine.

The invention solves current ion film caustic soda industry and adopt bariumchloride to remove the pollution problem that heavy metal barium that the sulfate radical method caused may cause environment, eliminate heavy metal barium, guaranteed the carrying out that produces, saved BaCL simultaneously the harm that environment causes ₂Expense.And also reduced solvay soda process soda ash produce in required refining agent consumption amount during salt refining, realized organic associating of ion film caustic soda and solvay soda process soda ash production, reached the purpose of resource sharing, mutual supplement with each other's advantages.

Description of drawings

Accompanying drawing is SO in the electrolysis with ion-exchange film caustic soda light salt brine fine of the present invention ₄ ^2-The schematic flow sheet of ion removal methods.

As shown in drawings, after storing, respectively defeated via the light salt brine that produces behind the ion-exchange membrane electrolyzer electrolytic brine Change salt operation and the supplementing water delivered in the ion film caustic soda preparation are produced and the production of ammonia-soda process soda ash for crude brine Brine section carries out the preparation of refined brine as changing salt solution; Wherein ion film caustic soda preparationization salt operation is produced Crude brine is transported to the ionic membrane electricity through being sent to after the salt refining after chelate resin tower carries out removal of impurities by chelating resin Separate groove and carry out electrolysis, and include SO with monitoring salt solution after the chelating resin removal of impurities₄ ^2-Amount be the control point, control is transported to be changed the salt operation and is used for light salt brine amount that crude brine produces with control SO in the ion film caustic soda preparation₄ ^2-Dense Degree, afterwards again control shunting deammoniation alkaline process soda ash production salt water conservancy project after equilibrium ion membrane electrolysis cells light salt brine amount The light salt brine amount of order, and it is in shortage to be used for the light salt brine that ion film caustic soda preparationization salt operation crude brine produces Can satisfy production by supplementing water.

Embodiment

Embodiment one

Ion film caustic soda is prepared a part after the light salt brine dechlorination that produces after the saline electrolysis in the intermediate ion membrane electrolyser and be transported to salt solution in the ion film caustic soda preparation and produce operation and the water of productive use salt that replenishes and prepare crude brine, after salt refining, be sent to the chelate resin tower removal of impurities then, and Monitoring and Controlling SO in the salt solution after the chelate resin tower removal of impurities ₄ ^2-Ionic concn is with Na ₂SO ₄Meter 4.5g/L also is transported to ion-exchange membrane electrolyzer and carries out electrolysis, and is sent to ion-exchange membrane electrolyzer salt solution with monitoring after the resin removal of impurities and includes SO ₄ ^2-Ionic weight is with Na ₂SO ₄Meter 4.5g/L is the reference mark, the crude brine that the light salt brine that employing accounts for light salt brine volume total amount 75% is used for the ion film caustic soda preparation is produced operation and is produced needs to satisfy, and remaining light salt brine is transported to the refined brine preparation process that solvay soda process soda ash is produced, and control SO ₄ ^2-Concentration is with Na ₂SO ₄Meter 7.5g/L carried out refined brine preparation to be used for soda ash production than 1: 15 as changing salt solution with the change brine volume of replenishing in the relative soda ash production of light salt brine.

Embodiment two

Ion film caustic soda is prepared a light salt brine part that produces after the saline electrolysis in the intermediate ion membrane electrolyser to be transported to salt solution in the ion film caustic soda preparation and to produce operation and prepare crude brine with the water of productive use salt that replenishes, after salt refining, be sent to the chelate resin tower removal of impurities then, and Monitoring and Controlling SO in the salt solution after the chelate resin tower removal of impurities ₄ ^2-Ionic concn is with Na ₂SO ₄Meter 4.8g/L also is transported to ion-exchange membrane electrolyzer and carries out electrolysis, and is sent to ion-exchange membrane electrolyzer salt solution with monitoring after the resin removal of impurities and includes SO ₄ ^2-Ionic weight is with Na ₂SO ₄Meter 4.8g/L is the reference mark, employing accounts for crude brine that light salt brine that the ion-exchange membrane electrolyzer electrolysis produces light salt brine volume total amount 80% is used for the ion film caustic soda preparation and produces operation and produce needs to satisfy, and remaining light salt brine is transported to the refined brine preparation process that solvay soda process soda ash is produced, and control SO ₄ ^2-Concentration is with Na ₂SO ₄Meter 7.5g/L carried out refined brine preparation to be used for soda ash production than 1: 25 as changing salt solution with additionalization brine volume in the relative soda ash production of light salt brine.

Embodiment three

Ion film caustic soda is prepared a light salt brine part that produces after the saline electrolysis in the intermediate ion membrane electrolyser be transported to salt solution in the ion film caustic soda preparation and produce operation and the water of productive use salt that replenishes and prepare crude brine, after salt refining, be sent to the chelate resin tower removal of impurities then, and Monitoring and Controlling SO in the salt solution after the chelate resin tower removal of impurities ₄ ^2-Ionic concn is with Na ₂SO ₄Meter 5g/L also is transported to ion-exchange membrane electrolyzer and carries out electrolysis, and is sent to ion-exchange membrane electrolyzer salt solution with monitoring after the resin removal of impurities and includes SO ₄ ^2-Ionic weight is with Na ₂SO ₄Meter 5g/L is the reference mark, employing accounts for crude brine that light salt brine that the ion-exchange membrane electrolyzer electrolysis produces light salt brine volume total amount 65% is used for the ion film caustic soda preparation and produces operation and produce needs to satisfy, and remaining light salt brine is transported to the refined brine preparation process that solvay soda process soda ash is produced, and control light salt brine SO ₄ ^2-Concentration is with Na ₂SO ₄Meter 9g/L, Ca in the light salt brine ²⁺+ Mg ²⁺≤ 30 μ g/L, additionalization brine volume was used as change salt solution and carries out refined brine and prepare to be used for soda ash production in producing with soda ash relatively with light salt brine than 1: 20.

Claims (3)

1, SO in the electrolysis with ion-exchange film caustic soda light salt brine fine ₄ ^2-The ion removal methods, it is characterized in that: the light salt brine that electrolytic tank electrolysis produces is after dechlorination is handled, removing the part shunting is used for the production of solvay soda process soda ash and carries out the salt solution preparation as changing salt solution, all the other light salt brine reuse salt operations prepare crude brine, the insufficient section make up water makes after refining, resin removal of impurities then and contains Na ₂SO ₄≤ 5g/L salt solution is transported to ion-exchange membrane electrolyzer and carries out electrolysis.

2, SO in the electrolysis with ion-exchange film caustic soda light salt brine fine according to claim 1 ₄ ^2-The ion removal methods is characterized in that: being transported to the production of solvay soda process soda ash as changing brinish light salt brine amount, is by to being transported to the SO in the ion-exchange membrane electrolyzer salt solution after the resin removal of impurities ₄ ^2-The control of concentration is adjusted.

3, SO in the electrolysis with ion-exchange film caustic soda light salt brine fine as claimed in claim 1 or 2 ₄ ^2-The ion removal methods is characterized in that: light salt brine SO ₄ ^2-Concentration is with Na ₂SO ₄Meter 7.5-9g/L.

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