CN1045319C

CN1045319C - Method for preparing sodium hydroxide by brine electrolysis

Info

Publication number: CN1045319C
Application number: CN94110856A
Authority: CN
Inventors: 周新法; 吴介正; 冯跃华; 李星垣
Original assignee: HUNAN CHEMICAL INDUSTRY DESIGN INST
Current assignee: HUNAN CHEMICAL INDUSTRY DESIGN INST
Priority date: 1994-03-03
Filing date: 1994-03-03
Publication date: 1999-09-29
Anticipated expiration: 2014-03-03
Also published as: CN1107903A

Abstract

The present invention belongs to the technical field of the production technology of sodium hydroxide, which relates to a method for preparing the sodium hydroxide by the electrolysis of whole bittern. In the method, underground caldo is exploited in a hydraulic mining method, and saltpeter in the bittern is removed in a freezing method to prepare refined bittern; salt as the side product generated in the following production process is added in the refined bittern after the saltpeter is removed, so the bittern achieves supersaturation, inorganic ammonia and organic ammonia are removed by heating the bittern to a high temperature and adding a deaminizating agent, and floating salt is removed by a floating salt settling bucket; finally, refined brine is obtained in a chemical refining method, the liquid of the sodium hydroxide is prepared by electrolysis, evaporation, concentration and the separation between the salt and alkali, and the salt as the side product can be circulated fro the supersaturation of the refined bittern. With the utilization of the method of the present invention, the sodium hydroxide can be produced from the whole bittern.

Description

The method of preparing sodium hydroxide by brine electrolysis

The invention belongs to the production technical field of sodium hydroxide, is a kind of method with preparing sodium hydroxide by brine electrolysis.

Industrial employing electrolytic process is produced caustic soda and chlorine has long history, and traditional production method mainly is to utilize sea salt to be dissolved into saturated brine electrolysis production sodium hydroxide and chlorine again.In recent years because sea salt transportation difficulty, cause the cost up with this explained hereafter NaOH, some producer's employing is at present mixed halogen technology and is reduced production costs, and mixes the halogen ratio and is 50% to the maximum, because it is different that the bittern mineral products are formed because of the region is different, resemble that to contain nitre in the bittern on ground such as Sichuan be saltcake (Na ₂SO ₄) amount very little, can reach about 30 grams per liters and contain the nitre amount in the salt mine bittern on ground such as Hubei, Hunan, sulfate ion content is bigger, and is very big to electrolytic influence, therefore with contain caldo mix halogen particularly perhalogeno system alkali, except that nitre, except that difficult problems such as ammonia are difficult to capture, can't realize making alkali production.

The method that the objective of the invention is to provide a kind of usefulness to contain the nitre preparing sodium hydroxide by brine electrolysis, make full use of the local caldo resource that contains, reduce production costs.

The objective of the invention is to realize with the following methods.The method that this usefulness contains the nitre preparing sodium hydroxide by brine electrolysis is from underground extraction with bittern, obtain thick bittern, thick bittern is cooled to after 5-25 ℃ through interchanger, add the freezing bittern temperature adjustment to 0 ℃ of band nitre through converting the halogen groove, send into crystallizer, 0-25 ℃ of freezing denitration down, making sodium chloride crystal is solid, contain the crystallization caldo and crystal is grown up and sedimentation crystal nitre, obtain to contain NaCL270-290 grams per liter, Na through settling vat ₂SO ₄6.5 the smart halogen that grams per liter is following, smart halogen carries out heat exchange with thick halogen in interchanger, smart halogen temperature is raise, thick brine temperature reduces, in smart bittern, add the by-product salt that the back evaporation section obtains then, make smart bittern reach supersaturation, heating supersaturated brine to 100 ℃ high temperature, add deamidization, make organic amine transfer inorganic ammonia to, inorganic ammonia in the supersaturated brine at high temperature volatilizees, and reaches salt solution and contains below ammonia 1 mg/litre, and adjusting deamination salt water ph value with acid is neutral about PH7, send floating salt settling bucket to remove floating salt only then, adopt the chemical refining method to obtain saliferous 315-320 grams per liter again, Ca ⁺⁺, Mg ⁺⁺(the refined brine that 10 mg/litre are following, refined brine carries out electrolysis after preheating, with the alkali lye that obtains after the electrolysis carry out evaporation concentration, saline and alkaline separation, salt is analysed in cooling, the salt of separating out is used for the supersaturation of smart bittern as by-product salt, obtaining liquid caustic soda at last is sodium hydroxide.

In the present invention, settling vat that heavy nitre is used adopts the inclined plate sedimentation bucket, utilizes gravity settling crystallization nitre, and the deamidization that adds in the supersaturated brine is a clorox, and the organic amine reaction production inorganic ammonia in clorox and the salt solution is easy to volatilize.Adjusting the used acid of deamination salt water ph value with acid is hydrochloric acid.Saturated brine (310-315 grams per liter) after heavy nitre and the deammoniation is owing to contain a large amount of floating salt, its particle surface adheres to one deck alkali film, easily build up the sclerosis caking, the clog up process equipment pipeline, cause producing and to carry out, to dissolve the floating salt that by-product salt (producing supersaturation bittern) that evaporation section reclaims produces be compact crystal type and unformed powder by containing the smart bittern of NaCL270-290 grams per liter, granulometric range is at 200-1500 μ, dissolution rate is slow, among the present invention, the clean method of removing floating salt is to adopt floating salt settling bucket, obtains good result by the mode of filtering with gravity settling.The floating similar Dao Er type of salt settling bucket settling tank, in establish central canal, divide into the mud layer fillter section, top is back taper type expanding reach, the floating salt loading salt solution that enters central canal is adjusted pH value in advance and is slight alkalinity, salt solution enters the macrobead filtering of mud layer fillter section with 800-1500 μ from central canal base cone portion, the 200-800 μ particle that sees through mud layer rises to expanding reach, because the particulate settling velocity is generally greater than in 0.6-1.0 rice/time scope, and expanding reach salt solution lift velocity sky relies on gravity settling to remove particulate clean only within 0.3-0.4 rice/time.In order to reach the good result of equipment, the strict insulation of floating salt settling bucket outer wall prevents that the convection current of the liquid phase temperature difference from influencing sedimentation, and is fixed in bucket for preventing particle, and the outer pH value that is provided with of bucket is adjusted supplementary unit and bucket end cleaning plant.

Embodiment:

In the somewhere, Hunan with the hydromining method with bittern from underground extraction, obtain to contain about 270 grams per liters of NaCL, Na ₂SO ₄The thick bittern of 25 grams per liters, thick bittern is cooled to 15 ℃ through interchanger, adds-10 ℃ freezing bittern of band nitre with extremely about 0 ℃ of thick bittern temperature adjustment through converting the halogen groove.Send into crystallizer decrease temperature crystalline, freezing under-12 ℃, making sodium chloride crystal is solid, and the bittern that contains solid nitre grows up crystal through first settling vat and second settling vat (first, second settling vat all adopts the inclined plate sedimentation bucket), utilizes the gravity settling crystallization to be Na ₂SO ₄H ₂O nitre obtains to contain Na behind the heavy nitre ₂The CL270-290 grams per liter, Na ₂SO ₄6.5 the smart halogen that grams per liter is following, smart halogen is carried out heat exchange with thick bittern that exploitation is come out in heat exchanger, thick brine temperature reduces, smart halogen temperature is grown tall, add by-product salt that evaporation section obtains then in smart bittern, make it reach supersaturation, supersaturated brine heated after 100 ℃, add the deamidization clorox, inorganic ammonia in smart halogen at high temperature volatilizees, organic amine and sodium hypochlorite reaction and generate inorganic ammonia and volatilize, reaching salt solution like this contains below ammonia 1 mg/litre, adjusting deamination salt water ph value with hydrochloric acid is neutrality (PH7), send then and floats the salt settling bucket only except that floating salt, carries out chemical refining except that adding Na2CO3 after the floating salt only, acquisition contains NaCL315-320 grams per liter, Ca ⁺⁺, Mg ⁺⁺The refined brine that meets the electrolysis requirement below＜10 mg/litre, send into electrolytic tank electrolysis, the electrolytic lye that flows out electrolyzer contains NaOH10-11%, stores at the electrolytic lye storage tank, concentrates with being pumped into evaporation unit, make 30%, 42%, 50% liquid caustic soda, divide salt through minute salt device or whizzer, after the saline and alkaline separation, liquid caustic soda is gone into storage tank and is cooled off heavy clear once more, after further analysing salt, be the liquid caustic soda finished product.Isolating by-product salt is capable of circulation, and to be used for smart bittern saturated again.

The inventive method whole production flow process has adopted 1, the cooling denitration, and 2, remove ammonia, 3, saturated again, 4, floating salt sedimentation process for refining step, make refined brine reach the standard that enters electrolyzer, satisfy the requirement of producing chlorine, hydrogen, caustic soda.The production process of the inventive method is all utilized the underground cheap bittern resource of China's abundant, do not need to add in addition sea salt or other Industrial Salt, reduce production costs, caustic soda per ton (100%NaOH) about 500 yuan of the salt cost (in January, 94 price) that can economize in raw materials makes manufacturer can obtain good economic benefits.

Claims

1, a kind of usefulness contains the method for nitre preparing sodium hydroxide by brine electrolysis, it is characterized in that bittern from underground extraction, obtain thick bittern, thick bittern is cooled to after 5-25 ℃ through interchanger, adds the freezing bittern temperature adjustment of band nitre to about 0 ℃ through converting the halogen groove, send into crystallizer, 0-25 ℃ of freezing denitration down, making sodium chloride crystal is solid, contains the crystallization caldo through settling vat crystal to be grown up and sedimentation crystal nitre, acquisition contains NaCL270-290 grams per liter, Na ₂SO ₄6.5 the smart halogen that grams per liter is following, smart halogen carries out heat exchange with thick halogen in interchanger, smart halogen temperature is raise, thick brine temperature reduces, in smart bittern, add the by-product salt that the back evaporation section obtains then, make smart bittern reach supersaturation, the heating supersaturated brine is to about 100 ℃ of high temperature, add deamidization, make organic amine transfer inorganic ammonia to, inorganic ammonia in the supersaturated brine at high temperature volatilizees, and reaches salt solution and contains below ammonia 1 mg/litre, and adjusting deamination salt water ph value with acid is neutral about PH7, send floating salt settling bucket to remove floating salt only then, adopt the chemical refining method to obtain saliferous 315-320 grams per liter again, Ca ⁺⁺, Mg ⁺⁺The refined brine that＜10 mg/litre are following, refined brine carries out electrolysis after preheating, with the alkali lye that obtains after the electrolysis carry out evaporation concentration, saline and alkaline separation, salt is analysed in cooling, the salt of separating out is used for the supersaturation of smart bittern as by-product salt, obtaining liquid caustic soda at last is sodium hydroxide.

2, usefulness according to claim 1 contains the method for nitre preparing sodium hydroxide by brine electrolysis, it is characterized in that the deamidization that adds in supersaturated brine is a clorox.

3, usefulness according to claim 1 contains the method for nitre preparing sodium hydroxide by brine electrolysis, it is characterized in that adjusting the used acid of deamination salt water ph value with acid is hydrochloric acid.

4, usefulness according to claim 1 contains the method for nitre preparing sodium hydroxide by brine electrolysis, it is characterized in that the settling vat that heavy nitre is used adopts the inclined plate sedimentation bucket, utilizes gravity settling crystallization nitre.

5, usefulness according to claim 1 contains the method for nitre preparing sodium hydroxide by brine electrolysis, it is characterized in that removing floating salt only with floating salt settling bucket, the floating similar Dao Er type of salt settling bucket settling tank, in establish central canal, divide into the mud layer fillter section, top is back taper type expanding reach, the floating salt loading salt solution that enters central canal is adjusted pH value in advance and is slight alkalinity, salt solution enters the macrobead filtering of mud layer fillter section with 800-1500 μ from central canal base cone portion, the 200-800 μ particle that sees through mud layer rises to expanding reach, because the particulate settling velocity is generally greater than in 0.6-1.0 rice/time scope, and expanding reach salt solution lift velocity was controlled within 0.3-0.4 rice/time, relied on gravity settling will float the salt particulate and removed clean only.