CN87102396A - The production of sodium chlorate - Google Patents
The production of sodium chlorate Download PDFInfo
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- CN87102396A CN87102396A CN87102396.2A CN87102396A CN87102396A CN 87102396 A CN87102396 A CN 87102396A CN 87102396 A CN87102396 A CN 87102396A CN 87102396 A CN87102396 A CN 87102396A
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Abstract
Come the technology of production sodium chlorate by the sodium-chlor of electrolysis contains sodium sulfate impurity, wherein the concentration of vitriol remains below the level of a preliminary election in system.The residue mother liquor that goes out some sodium chlorate products through crystallization can selectively further be cooled to make some sulfate crystals that exist in solution to come out.Set up an acceptable " steady state " sulfate ion concentration, can avoid in electrolytic system sulfate ion excess accumulation nocuously.
Description
The present invention relates to by electrolytic sodium chloride aqueous solution, the sodium chloride aqueous solution that particularly contains sulfate impurities prepares sodium chlorate.
With electrochemical appliance and prepared sodium chlorate is on record, and is widely used in the industrial production of this compound.It is known producing chlorine and sodium hydroxide and produce clorox from electrolyzer by electrolytic brine, according to reaction formula:
Hypochlorous acid can be converted into chloranion and chlorion as can be known.In fact sodium-chlor combine with water and generate sodium chlorate and hydrogen in electrolytic system like this.Electrolysis generally under 60-90 ℃, is carried out in the electrolyzer of titanium anode that includes the covering of precious metal or metal oxide containing precious metals and steel negative electrode, and puts into the efficient of a spot of sodium dichromate 99 with kind entire reaction in solution.In technology, add sodium-chlor and water, produce a kind of sodium chlorate that comprises, the solution of sodium-chlor and sodium dichromate 99.
Increase owing to be covered with titanium anodic precious metal or metal oxide corrosive, in fact all sodium chloride electrolysis can not be become sodium chlorate.The liquid of general product is at least every liter 100 gram (100gpl) with sodium chloride-containing, and the general content range of Potcrate is the 350-650 grams per liter.
The sodium chloride salt that generally is used to prepare electrolytic brine is rock salt and solar salt shan.The operation of the impurity decision sodium chlorate electrolyzer that these two kinds of Yanyuans are contained.This typical impurity is calcium ion, and it can increase the resistance of electrolyzer like this in the cathodic deposition of electrolyzer.Cause the raising of running cost owing to having consumed extra electric energy.Generally before entering electrolyzer, use yellow soda ash, sodium-hydroxide treatment salt solution, the content of calcium reduces to and is lower than 10ppm in the salt feed liquid, and the concentration of magnesium is lower than 1ppm.Though can be by preliminary treatment reduce the precipitation influence of calcium ion to salt solution with chemical, still have some calcium to be present in the salt solution and be accumulated in the electrolyzer, and increase the consumption of electrolytic energy, cause the increase of running cost.In recent years, after through chemical treatments salt solution, generally increase a secondary purification step, this method is to use ion exchange resin to remove calcium and magnesium from salt brine solution.Typical this resin is Duolite ES467* and Rohm and Haas IRC718*.These resins can reduce to the content of calcium and magnesium and be less than 50/1000000000ths, (50ppb) reduce to 25ppb especially.This secondary purification step is for the regional particularly advantageous that the electric lighting bill is heavy.Sodium chlorate is the raw material that is used to make chlorine dioxide, and this gas is soluble in water to be used for bleaching paper.Sodium chlorate is as the production dioxide peroxide time, and it generally is to produce dioxide peroxide with sulfuric acid reaction, chlorine and sodium sulfate.Because the sodium chlorate that is used in the chlorine dioxide production is the aqueous solution, therefore electrolytic production liquid can be directly used in the chlorine dioxide generator.The device of producing liquid product trend towards being located at relevant chlorine dioxide generator near so that reduce the required expense of the big water gaging of transportation as far as possible.Yet this has a shortcoming, in the sodium chlorate of selling as liquid, contains and adds the sodium dichromate 99 that is used to improve process efficiency in the electrolyzer, increases certain production cost owing to sodium dichromate 99 can lose in production equipment.
The supply each side employs visitor's commercial chlorine hydrochlorate producer generally to produce the sodium chlorate crystal, has therefore significantly reduced transportation cost and the loss of having avoided sodium dichromate 99.The technology of producing the crystal sodium chlorate is on record.Generally produce liquid and be transported to that vacuum cyrsytalliser cools off and with the water evaporation, produce the crystalline sodium chlorate the 60-90 ℃ of heat that will contain sodium chlorate and sodium-chlor.By selecting suitable process conditions, sodium-chlor can maintain in the solution, and like this through after pure substantially sodium chlorate crystal is separated from mother liquor continuously, but electrolyzer is returned in mother liquor recirculation.Though can come drying by bypass in some operations, the oxymuriate crystal generally also needs to be dried and shipment.
In above-mentioned crude salt except calcic magnesium and magnesium addition generally also there to be sulfate ion in the external Industrial Salt.When this salt directly uses with salt or brinish form, and when not taking special step to remove vitriol, vitriol can enter electrolysis system.
Sulfate ion remaining unchanged under the condition of electrolytic system make that it just can accumulate if do not take some step to be removed, thereby the concentration in system increases constantly.In the sodium chlorate device of producing liquid product, sulfate ion can be stayed in the product solution.Yet there is no, the device of only producing the crystal sodium chlorate provides the device of getting rid of carbanion.Therefore the sulfate ion in the salt is after entering electrolytic system, still stays in the mother liquor and is circulated back in the electrolyzer through Crystallization Procedure.Time one, long sulfate ion concentration can increase, if sulfate concentration causes the local deposits in electrolyzer when reaching enough high, can seriously influence electrolytic energy expenditure and cause operational problem.For example, reach 30 grams per liters when above when the concentration of vitriol is equivalent to sodium sulfate concentration, and according to electrolytical concentration and temperature, vitriol will deposit in electrolyzer, thereby limited electrolytical circulation, will seriously have influence on electrolytic energy expenditure and obducent life-span of anode.Under the operational condition of general electrolyzer and crystallizer, this effect in electrolyzer also can occur in the situation that sulfate concentration is lower than the saturation concentration of mother liquor in the crystallizer.Therefore general crystallizer can not drop to the concentration of vitriol the level that is appropriate to electrolytic system concentration.Because the solubleness of sodium sulfate is essentially constant in by the actually operating temperature range that vacuum cooling reached in mother liquor, therefore in fact the saturation concentration of vitriol in the vacuum cyrsytalliser mother liquor can not be reduced to an acceptable level.
Ining all sorts of ways at present is controlled at the concentration of vitriol in the oxymuriate crystallization apparatus, but every kind of method all has its shortcoming.
Can make that vitriol remains on an acceptable concentration in the system by the method for removing oxymuriate liquid, promptly discharge solution of chlorate, yet must determine by vitriol amount in the salt as the minimum part in the ultimate production of liquid discharge, and this is not to determine by market demands, and this minimum part may be very big.In addition, this liquid product has sodium dichromate, if do not need to have sodium dichromate 99, that is with its displacement or remove and all need expense.This working method needs a fire exit of selling solution, but owing to higher freight charges have reduced economic worth.Same this also is different from as crystalline transportation output but provided the upper limit ratio of plant capacity.
The method of another control sulfate concentration is to be input into the feed liquid of crystallizer or to generate the relative sulphate cpd that is insoluble to the solution from mother liquor and the reaction of some chemical that crystallizer is exported.Particularly with the reaction of bariumchloride or barium carbonate with generate barium sulfate and with the reaction of calcium chloride to generate calcium sulfate.In some cases with barium compound reaction better, this is particularly suitable with the factory that prevents from calcium is introduced electrolyzer with ion exchange treatment salt solution to those.But this technology also has several shortcomings.
A main drawback is to add excessive barium compound can make excessive barium enter electrolyzer.Can make the anode coverture that the deposition of one deck barium sulfate is arranged and be unfavorable for the operation of electrolyzer.Barium also can generate baryta yellow with the chromic salt reaction except reacting with sulfate ion, therefore must add the barium of q.s so that react with chromic salt and vitriol.Therefore lost the part meaning that adds barium.Barium compound and sodium dichromate 99 are expensive, so this has just wasted appreciable chemical reagent.And resulting barium sulfate must separate with chromic acid rule slurries, and the solids of gained must be thrown aside, and certainly will need certain fund and process cost.
Another shortcoming is to produce calcium sulfate with the reaction of calcium chloride.This reaction needed adds the concentration of staying sulfate liquor in the solution than the more calcium of stoichiometric quantity in the solution with control.As mentioned above, calcium to battery-operated be deleterious, therefore excessive calcium must be removed, this generally can become lime carbonate with calcium deposit by adding yellow soda ash.Yet, not all calcium can both be removed in the brine treatment process by above-mentioned method, removing remaining calcium by ion exchange resin from solution of chlorate still fails industrialness and uses, therefore this method comprises two reactions steps, per step all needs separate solid, and the solid after the separation must be thrown aside again.
Another shortcoming be exactly through barium or calcium handle that the solid that is produced will be polluted by the chromium in chromic salt or the dichromate, this is deleterious to environment.
The purpose of this invention is to provide and a kind ofly produce the technology of solid sodium chlorate from the sodium-chlor that contains sulfate impurities, this technology has reduced the detrimentally affect of vitriol to the electrolyzer energy expenditure.
Another object of the present invention provides the method for an economy and remove excessive vitriol from the technological process of production sodium chlorate, and don't need add chemical feedstocks in addition.
The further target of the present invention provides a kind of technology of electrolysis production sodium chlorate, and don't can lose a large amount of dichromates from system.
Therefore the purpose of this invention is to provide a continuous production and the electrolysis process of removing pure basically sodium chlorate, in electrolytic system, the dense exhibition of sulfur impurity hydrochlorate can not surpass the limit that institute requires and selects.Pure sodium chlorate can obtain by the selective freezing of the aqueous solution recycle system, and sodium sulfate and the extra dual crystallization of sodium chlorate are carried out in the product mother liquor of less part in the mixture, and the most and less part exhausted Recycling Mother Solution of product mother liquor is returned electrolyzer.
Therefore, the invention provides one and come the improvement continuous processing of production sodium chlorate, in electrolysis process, comprise by electrolytic sodium chloride:
A) sodium-chlor of water and sulfur acid salt impurity is added reaction zone, above-mentioned therein sodium-chlor is electrolyzed to produce chlorine and sodium hydroxide, and above-mentioned chlorine and sodium hydroxide reaction generate clorox, and reaction generates the solution of rich sodium chlorate then;
B) solution of the above-mentioned rich sodium chlorate of cooling, crystallization goes out sodium chlorate partly, obtains sodium chlorate crystal and a kind of sodium chlorate that comprises, the mother liquor of sodium-chlor and vitriol;
C) isolate above-mentioned sodium chlorate crystal;
Wherein improve and comprise;
D) above-mentioned most Recycling Mother Solution is returned above-mentioned reaction zone;
E) mother liquor with above-mentioned less part is cooled to such temperature, makes wherein to come out with the form of sodium sulfate and a part of above-mentioned sulphate crystal of above-mentioned sodium chlorate mixture, and produces a kind of cold saturated solution of waste liquor;
F) from above-mentioned waste liquor, separate above-mentioned mixed crystal;
G) above-mentioned waste liquor is recycled to above-mentioned reaction zone; The amount of wherein above-mentioned little part mother liquor is chosen the concentration that just makes vitriol in above-mentioned reaction zone and is remained essentially on the predetermined constant level.
Reaction zone can just be represented electrolyzer itself, also can further comprise a retort, wherein imports electrolysate, and holding is not clorox, and the reaction of oxymuriate takes place to generate described electrolysate.Electrolysis can be carried out in any suitable electrolyzer that suitable anode and negative electrode be housed.Barrier film or film can be equipped with or not be equipped with between the anode of electrolyzer and the negative electrode.If do not have this barrier film or a film, the chlorine that generates of anode can and the caustic soda reaction generation sodium chlorate that produces of negative electrode.The preferred chloric acid type electrolyzer example that United States Patent (USP) proposes for No. 3732153 can be used for the present invention.Yet be equipped with by the electrolyzer of single asbestos or the film made with resin type polymeric material enhanced asbestos diaphragm or from the cation selective permeable material such as those and can be used for the present invention from the electrolyzer that provider of E.I.Du Pont Company is designated as " Nafion ".The chloric alkali electrolysis mould of United States Patent (USP) 3464901 and No. 3897320 disclosed barrier films and film-type can be used to produce the alkaline metal chlorate according to the present invention.
Through finding that the solubleness of its sodium sulfate can descend suddenly when mother liquor that pure sodium chlorate selective freezing is basically come out is cooled to below the temperature of its normal sodium chlorate vacuum crystallization.As contain 36% sodium chlorate, 9% sodium-chlor, 2.1% solution is saturated to sodium sulfate in the time of 60 ℃, the solubleness of sodium sulfate almost remains unchanged when temperature is reduced to about 10 ℃, yet under 5 ℃ or lower temperature, the saturation concentration of sodium sulfate has advantageously dropped about 2 to 4 times, to contains sodium sulfate 1.25% to 0.4 to 0.5%.Sodium chlorate solution's solubleness is reduced to and is helped sodium sulfate and the sodium chlorate cocrystallization is come out when also finding solution is chilled to-5 ℃.By removing the little part effluent of mother liquor, and further cool off this effluent, can obtain the mixed crystal of sodium sulfate and sodium chlorate, can be with crystal separation, and with waste liquor recirculation.By selecting the few partly flow velocity of effluent of that coolings, the sodium sulfate that goes out from the system crystallization can come balance by the vitriol that together enters electrolytic system with raw material salt.Concerning the sulfate concentration that is generally run in raw material salt, institute's refrigerative effluent is only represented part seldom of total mother liquor liquid.Therefore process cost is low, and the heat exchange between effluent that also can be by entering water cooler and the cold waste liquor that leaves water cooler reduces to lower to expense.The sodium sulfate of gained may not have any harm in mixture, because it also is to use the byproduct in the production of sodium chlorate dioxide peroxide method.
For what present technique field professional obviously easily saw be, vitriol is not single to be the impurity of raw material salt only, the impurity that also can be used as water directly, or enter the oxymuriate production process as a component of salt solution feed liquid, also since in the production process chemical reaction produced, generate vitriol as oxidation by sulfide.Clearly, method of the present invention can be removed the vitriol of introducing in any of these source equally effectively or be controlled its concentration.
Therefore might be cooled to a suitable temperature makes the speed that folds vitriol from the relatively little of crystallizer materials flow and predetermined partly binode crystalline substance equal the stream hydrochlorate input speed as the material salt impurity.Thereby in electrolytic system, the concentration of vitriol can be remained on a stable level, this level with comprise that the whole technological process of electrolyzer adapts.Preferably the materials flow of secondary crystallization device comes the mother liquor of the crystallizer of autonomous or one-level flash distillation or evaporation oxymuriate.
Therefore preferable feature of the present invention provides an aforesaid technology, and wherein above-mentioned few mother liquor partly is chilled to 5 ℃ or lower temperature range, preferably about-5 ℃.
Discovery is in-5 ℃ or lower temperature range, in the oxymuriate/muriate liquid component that is suitable for the oxymuriate crystallization processes of flash distillation or evaporation oxymuriate crystallizer, and being lower than facing under Jie's concentration of electrolytic process in the concentration of vitriol, sodium sulfate will crystallize out together simultaneously with sodium chlorate.In secondary crystallisation by cooling step, the sodium chlorate crystal can produce with a predetermined amount together with sodium sulfate.Yet this only produces pure sodium chlorate crystal's small portion for the primary crystallization device, and is easy to handle.As a result, one all-the crystallization consecutive steps in, be equivalent to all amounts that enter the sulfur impurity hydrochlorate and will exist in the mixed crystallization product.The ratio of vitriol and oxymuriate was very little during sulfate concentration in primary crystallization device crystal product was removed with respect to minimal liquid.
The technology of removing vitriol and control sulfate concentration can be at an easy rate and existing oxymuriate crystal system combination.
Vitriol can also be removed by the primary crystallization device being transferred to same low temperature, and this just needs the cooling load of a bigger not very economical, thereby needs one consistently for this purpose and specially designed crystallizer.
One of skill in the art can be readily appreciated that relative quantity most and less part can easily be measured according to the sulfate concentration value of required steady state in the electrolytic system and select in the described mother liquor.Clearly, in order to keep the steady-state concentration of vitriol in technological process, the amount of removing vitriol by the secondary cooling must equal to enter vitriol amount in the technological process with salt.The concentration of vitriol is high more in material salt, and the amount of sending the less part mother liquor of secondary refrigerative to is big more.If will change the sulfate concentration of steady state in solution, the amount that can increase temporarily or reduce less part mother liquor according to the increase or the minimizing of sulfate concentration.Must comprise the shortcoming aspect the economic cost that cools off less part mother liquor and and between concentration that electrolytic system reduces vitriol is with the amount advantageous effect that determines less part effluent, make balance.
The residing temperature of rich sodium chlorate solution is easy to be selected by those of skill in the art in the one-level water cooler.From using flash distillation or evaporation sodium chlorate operating restraint shows in the experience of the traditional technology gained of 18 ℃ to 40 ℃ prilling tower, when the concentration of vitriol is increased to certain some material, sulphate cpd is not saltoutd in crystallizer, but salt is torn open in electrolyzer.Yet in technology of the present invention with this liquid cooling at least in 18 ℃-40 ℃ the scope, this is favourable on economic cost.
The further preferred feature of the present invention has provided an aforesaid technology, and wherein the concentration of sodium sulfate is no more than 30 grams per liters in electrolytic system.
The input of the sodium-chlor batching of sulfur acid salt impurity must provide enough sodium-chlor to electrolytic process, also will consider the impurity concentration of gained vitriol in solution simultaneously.The characteristics of successive processes of the present invention are that the concentration of vitriol keeps constant basically, and this can reach by the sodium-chlor raw material of adding the vitriol that enough amounts that contains with the shift-in second cooling sodium sulfate are complementary.Contain form or the solid form that the sodium-chlor batching of impurity can the aqueous solution and add electrolytic system.It can directly add the inlet that electrolyzer is added the salt solution raw material, adds in the circulation waste liquor, or adds in the reaction zone with any other suitable method.
Therefore the further feature of the present invention provides an aforesaid technology, and the sodium-chlor of wherein above-mentioned contains sodium sulfate impurity adds above-mentioned reaction zone with the form of the aqueous solution.
The present invention more provides an aforesaid technology in further feature, wherein the less part of above-mentioned mother liquor is cooled to such temperature, make and the above-mentioned sulfate crystal of sodium chlorate blended some, think sodium sulfate and stay in the above-mentioned cold saturated waste liquor vitriol, concentration is no more than 10 grams per liters, preferably is no more than 7 grams per liters.
Clearly, it is feasible removing impurity sodium sulfate by traditional chemical precipitation approach from the mixture of sodium sulfate-sodium chlorate.
One with every day 0.5 ton sodium sulfate as the device of vitriol input in the compound of available ca or barium will expect that the chemical of salt precipitates.
The reaction precipitation of calcium (as calcium chloride) and sodium sulfate goes out calcium sulfate.Approximately need generate about day 0.5 ton calcium sulfate with 0.4 ton calcium chloride and 0.5 ton sodium sulfate reaction every day, and need and throw aside its separation.
In order to guarantee favourable reaction conditions, need with the excess chlorination calcium that surpasses and sodium sulfate reacts.General every day, calcium chloride was excessive 0.2 ton.In fact calcium chloride must be removed by reacting with yellow soda ash, makes the calcium amount that enters electrolyzer reduce to minimum.The requirement of yellow soda ash is made an appointment with 0.2 ton of every day.Every lime carbonate that produces 0.2 ton approximately need and be thrown aside its separation.
In order to make the easier understanding of the present invention, existing illustrates an optimum implementation by example, and referring to accompanying drawing, the electrolysis process of continuous production sodium chlorate of the present invention is described with schema wherein.
In schema, contain Ca
++, Mg
++And So
-- 4The sodium-chlor of ionic impurity arrives chemical purification jar 12 through managing 11, and adds sodium hydroxide and yellow soda ash therein, is settled out lime carbonate and magnesium hydroxide, and they are removed by filter.The salt solution of handling flows to ion exchange tower 14 further to remove remaining Ca through managing 13
++And Mg
++Ion makes their concentration be lower than 50/1000000000ths.Salt solution after purifying flows to electrolyzer 16 by managing 15, and adds acid and regulate its pH value, and wherein a part of muriate is transformed into oxymuriate.Cell liquid flows to the elementary flash evaporation crystallizer of operating 18 through managing 17 under vacuum.Solution flash is cooled to about 20 ℃ therein, and crystallization goes out pure basically sodium chlorate.The sodium chlorate crystal is removed, and the most of mother liquor is recycled to electrolyzer 16 through managing 19.The less part of mother liquor wherein is further cooled to a temperature that makes sodium sulfate and sodium chlorate generate dual crystalline mixture by managing 12 from ion-exchanger 21 secondary cooling crystallizer 22 into.Waste liquor in the secondary crystallization tower 22 reaches the mother liquor of precooling pipe 20 those less parts by heat exchanger 21, and is recycled to electrolyzer 16.Collect mixed crystal, fresh salt solution is sent electrolyzer 16 by managing 15 to continuously as preparation raw material.
The example I
Technology shown in the schema among the figure is that the sodium chloride salt of soluble sulphate is a raw material to contain 1% sodium sulfate, the operating procedure of 100 tons of sodium chlorate factories of daily output.The steady-state concentration of sodium sulfate in electrolytic solution need remain on 20 grams per liters.
Salt is soluble in water and be settled out calcium and magnesium compound through chemical treatment in jar 12, further purify through ion exchange tower 14 then, make calcium and magnesium dense to be lower than 1,000,000,000 fens be 50 to being reduced to.The solution that purified salt solution goes out from electrolyzer 16 electrolysis contains 620 grams per liter NaClO in the time of 60 ℃
3, 110 grams per liter NaCl and 20 grams per liter Na
2SO
4
Electrolytic solution in the electrolyzer 16 is introduced crystallizer 18, and it is operated under vacuum, and wherein solution flash is cooled to 20 ℃ of crystallizations and goes out pure sodium chlorate, and crystal sodium chlorate output is 95.4 tons of every days.
The mother liquor of crystallizer contains 520 grams per liter NaClO
3, 130 grams per liter NaCl, 30 grams per liter Na
2SO
4, the direct recirculation telegram in reply of more most mother liquor is separated system, and the effluent of less part mother liquor further is cooled to-5 ℃ approximately in an isolating secondary crystallization device.Crystallization every day goes out 0.55 ton of Na in this container
2SO
4With 4.6 tons of NaClO
3
Have a daily output of 95.4 tons of pure NaClO
3+ 4.6 tons (with Na
2SO
4Blended NaClO
3100 tons of)=every days.
Na in second reactor 22 productions
2SO
4And NaClO
3Crystalline mixture contains 11% the Na of having an appointment
2SO
4If this mixture is added to the NaClO that is produced by crystallizer 18
3In the crystal, that gained total amount every day is that 100.55 tons mixture on average comprises 99.45% NaClO
3With 0.55% Na
2SO
4
Rely on the removing electrolytic solution to remove Na for one
2SO
4With the Na that keeps in the electrolyte solution
2SO
4Steady-state concentration remain on the technology of 20 grams per liters, clearly, at first need to increase the NaCl(that sends in the technological process and have Na
2SO
4) amount remove in the solution because NaCl also is present in, next speed of removing solution (has NaClO in solution
3) decide forming of liquid by the concentration and the removing of sulfosalt in the material salt.If having, the removing liquid of taking from electrolytic solution consists of 620 grams per liter NaClO
3, 110 grams per liter NaCl, 20 grams per liter Na
2SO
4, the removing liquid stream of that every day will contain 18 tons NaClO
3, the Na of 3.2 tons NaCl and 0.55 ton
2SO
4, and the about 30m of the cumulative volume of every day
3Therefore, only may produce 82 tons of crystal NaClO every day in crystallizer
3Produce 30m simultaneously daily
3Liquid product, wherein contain 18 tons of NaClO
3, and this solution will contain promising NaClO
3The Na of ratio 3.2%
2SO
4In addition, if the concentration of sodium dichromate 99 in electrolytic solution generally remains on 4 grams per liters, remove liquid and will contain 0.12 ton of sodium dichromate 99 every day.
Generally speaking, if the concentration of vitriol is to control by solution removal, although factory's production every day is 100 tons NaClO so
3, but to have every day 18 tons as solution that is disposed, only produce 82 tons of crystal products.In addition, because need add 3.2 tons of NaCl and 0.12 ton of Na every day in addition
2CrO
7To getting rid of in the liquid stream, consumption of raw materials will increase in the technological process.
The table I is listed sodium chlorate in several at various temperatures typical mother liquors, the concentration of sodium-chlor and sodium sulfate.Demonstrate in the table when being cooled to-7 ℃ that the solubleness of sodium sulfate has an absolute and relative ground to descend suddenly in the mother liquor.
The table I
Temperature NaClO
3% NaCl% Na
2SO
4%
60℃????34.7????11.1????2.1
36.2????9.1????2.1
37.0????7.5????2.1
20℃????31.2????12.0????2.2
31.9????11.7????2.2
32.8????10.0????2.2
33.9????9.5????2.1
37.3????6.2????2.1
10℃????32.2????10.0????2.1
33.8????8.0????2.1
38.2????5.7????2.1
4℃????1.25
0℃????1.05
-3℃????0.83
-5℃????0.70
-7℃????32.3????9.0????0.55
34.3????6.6????0.45
Because mixture does not have chromium cpd on substantially, therefore available barium salt becomes BaSO with sulfate precipitation
4, for example can remove by filtering or staticly settling, clarifying then solution of chlorate returns in the technological process.As mentioned above, the Ph value is reduced or carefully controlled unless contain dichromate and barium ion in the chlorate electrolysis solution, otherwise will precipitate into BaCrO
4And BaSO
4Technological process of the present invention provides one can avoid the sedimentary chance of chromium cpd, and therefore the less slurries that discard produce a kind of slurries that do not contain chromium that help environment, and reduces the consumption of barium ion.The method of available permutations and must from system, chromium not being removed.
Therefore, the present invention further provides an aforesaid technology, wherein the mixture with above-mentioned sodium sulfate and sodium chlorate is dissolved in the water, and handle with barium compound, generate barium sulfate precipitate, remove above-mentioned barium sulfate, gained solution is recycled in the above-mentioned electrolytic process.
Another selection is the oxymuriate of secondary crystallisation by cooling and sodium sulfate solid mixture can be added in the oxymuriate solid that is installed in the one-level crystallizer before the common hot air dryer.The effect of moisture eliminator is to help vitriol solid and the wet dirt washer of oxymuriate powders into.Dust scrubber liquid can be handled to remove vitriol by the aforesaid method with same advantage.
The table II is listed, under the same operational condition of example one, when factory produces 100 tons of NaClO in day in the material salt concentration of vitriol to product, the influence that salt and dichromate distribute.In prior art processes, use and remove solution and control the concentration of vitriol, and technology of the present invention is controlled its concentration in electrolytic solution (B) with sodium sulfate crystal in a secondary cooling crystallizer at electrolyte solution (A).
In the table II, capable A(1 splits) and B(1) be illustrated in the concentration of various vitriol in the material salt.Capable A(2 splits) be illustrated in the solution as removing the NaClO amount that liquid must shift out, capable A(3 splits) expression produces NaClO
3The crystalline amount.Capable A(4 splits) represent to be input in the technological process to satisfy the NaCl total amount of crystallization and solution removal needs.Capable A(5 splits) represent from operating process, to leave away along with removing solution, and add the amount of the sodium dichromate 99 in the technological process again.Clearly, along with the increase of sulfate concentration in the salt, increased producing crystal NaClO
3The restriction of deal reaches the consumption that has also increased NaCl and sodium dichromate 99.
In the table II, capable B(2 splits) produce the crystalline NaClO that obtains in the expression secondary cooling crystallizer
3And Na
2SO
4Amount, capable B(3 splits) NaClO that produces in the expression one-level crystallizer
3The crystal amount, capable B(4 splits), B(5), B(6) expression is no matter the concentration of vitriol is how in material salt, the NaClO that produces
3Total crystal amount remain on 100 tons of every days, the composition that the NaCl requirement remains on 55 tons of every days, sodium dichromate 99 need remain zero.
The A of comparison sheet II and B partly can find that technology of the present invention has tangible advantage than existing technology, and be particularly more obvious the salt of increase sulfate impurities in those content.
The table II
A. only remove vitriol (electrolytic solution) by solution removal
（1）????（2）????（3）????（4）????（5）
SO
4With Na
2SO
4Crystallization NaClO in removing liquid
3Being input into the total dichromate of NaCl becomes
Be present in % NaClO in the salt
3Ton per day ton per day amount ton per day part ton per day
0????0????100????55.0????0
0.2????3.5????96.5????55.6????0.02
0.5????8.8????91.2????56.6????0.06
1.0????18.0????82.0????58.2????0.12
2.0????38.3????61.7????61.8????0.25
3.0????61.3????38.7????65.9????0.40
B. only remove vitriol (electrolytic solution) by the secondary cooling crystallizer
（1）????（2）????（3）????（4）????（5）????（6）
SO
4With secondary crystallization at the total NaClO of one-level crystallization
3Be input into the NaCl dichromate
Na
2SO
4NaClO
3/ Na
2SO
4In NaClO
3Crystallization total amount composition
Be present in ton per day ton per day ton per day ton per day ton/part
% in the salt
0????0????0????100????100????55????0
0.2????1.2????0.11????98.8????100????55????0
0.5????2.3????0.28????97.7????100????55????0
1.0????4.6????0.55????95.4????100????55????0
2.0????8.8????1.10????91.2????100????55????0
3.0????12.6????1.65????87.4????100????55????0
Therefore, the invention provides one and have the technique that following advantage is produced sodium chlorate continuously:
ⅰ) this technique provides one to produce continuously all products from sodium chlorate factory all is the method for chloric acid crystal, and the used salt that contains sulfate of the method needn't pass through solution removal and chemical treatment.
ⅱ) owing to needn't pass through solution removal, having reduced needs the sodium chloride amount of purification, and does not need the sodium dichromate composition.
ⅲ) since the chemical grout that comes the precipitated sulfur hydrochlorate to produce with calcium or barium compound do not existed, relevant reaction and separation processes slurries expense therewith, the operating cost of chemicals, manpower and the expense of slurries of throwing aside do not need.
ⅳ) remove from device in the form of the sulfate impurities of material in the salt sour sodium and sodium chlorate mixture with acid. The end user selectively replaces the loss of sulphur in the used technical process of user with this sodium sulphate. Therefore has economic worth.
ⅴ) dry mixture through the secondary cooling also merges with dry crystal, or transports under the residual moisture that can also bring in the design apparatus according to the present invention.
If ⅵ) need not sodium chlorate crystal's product of containing sulfate, can be water-soluble and obtain through chemical treatment through the sodium chlorate of secondary cooling step cocrystallization/sodium sulphate mixture. Because the solution of gained there is no sodium dichromate or chromate, so the consumption of barium compound only need be used for and the sulfate reaction is just enough, so just reduced the consumption of chemicals. If use calcium compound, after forming solution, when the sulfate concentration in the liquid was very high, required amount can reduce, and so just must add that excessive calcium reduces to minimum to guarantee favourable reaction condition in the reaction.
ⅶ) need not add the compound of calcium and barium in technical process, these two kinds of compounds are all harmful to electrolytic cell operation.
ⅷ) this technique has reduced the operating cost of Sodium Chlorate crystallization device.
ⅸ) the buying price of salt, at the content that depends on to a certain degree impurity in the salt, this technique can be used the higher sodium chloride of sodium sulphate content, can reduce the expense of raw material.
Claims (7)
1, one is come the improvement continuous processing of production sodium chlorate to comprise by electrolytic sodium chloride in electrolytic process:
A) with water and have the sodium-chlor of sodium sulfate impurity to add reaction zone, the above-mentioned sodium-chlor of electrolysis therein becomes chlorine and sodium hydroxide, described chlorine and the anti-clorox that produces into of sodium hydroxide, and reaction generates the solution of rich sodium chlorate then;
B) solution of the above-mentioned rich sodium chlorate of cooling, crystallization goes out above-mentioned sodium chlorate partly, obtains sodium chlorate crystal and a kind of sodium chlorate that comprises, the mother liquor of sodium-chlor and vitriol;
C) separate above-mentioned sodium chlorate crystal;
Wherein improve and comprise;
D) Recycling Mother Solution of above-mentioned major part is returned above-mentioned reaction zone;
E) mother liquor with above-mentioned less part is cooled to such temperature, form and the above-mentioned sulphate crystal of above-mentioned sodium chlorate blended with sodium sulfate is come out, and produce a kind of cold saturated solution of waste liquor;
F) from above-mentioned waste liquor, separate above-mentioned mixed crystal;
G) above-mentioned reaction zone is returned in above-mentioned waste liquor recirculation; The amount of wherein above-mentioned less part mother liquor is chosen the concentration that just makes at above-mentioned reaction zone vitriol and is remained essentially on the predetermined constant level.
2, technology according to claim 1, wherein said less part mother liquor is cooled to about 5 ℃ or following temperature.
3, technology according to claim 2, wherein said less part mother liquor are cooled to-5 ℃ approximately.
4, technology according to claim 1, wherein said less part mother liquor is cooled to such temperature, form and a part of above-mentioned sulphate crystal of above-mentioned sodium chlorate blended with sodium sulfate are come out, make the sodium sulfate of staying in the described cold saturated waste liquor be no more than 10 grams per liters as the concentration of vitriol.
5, technology according to claim 4 is wherein stayed and above-mentionedly in the described cold saturated waste liquor is thought that the sulfate concentration of sodium sulfate is no more than 7 grams per liters.
6,, think in electrolytic system that wherein the sulfate concentration of sodium sulfate is no more than 30 grams per liters according to any one described technology of claim 1 to 5.
7, according to any one described technology of claim 1 to 5, wherein the mixture of sodium sulfate and sodium chlorate is soluble in water, and handle the precipitation that generates the sulfuric acid hydrochlorate with barium and calcium solution, remove above-mentioned sulphate cpd above-mentioned electrolytic system is got back in surplus solution recirculation.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US84462086A | 1986-03-27 | 1986-03-27 | |
| US844,620 | 1986-03-27 | ||
| US844,62-8 | 1986-03-27 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN87102396A true CN87102396A (en) | 1987-10-07 |
| CN1012441B CN1012441B (en) | 1991-04-24 |
Family
ID=25293233
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 87102396 Expired CN1012441B (en) | 1986-03-27 | 1987-03-27 | Production of sodium chlorate |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1012441B (en) |
Cited By (7)
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| CN101922014A (en) * | 2010-08-17 | 2010-12-22 | 刘亨益 | Diaphragm process chlorine generator and preparation method of sodium hypochlorite |
| CN101787541B (en) * | 2010-01-26 | 2011-08-17 | 四川金路集团股份有限公司 | Method for removing nitrates through CIM membrane method |
| CN102465311A (en) * | 2010-11-19 | 2012-05-23 | 中国水利水电科学研究院 | Preparing system and method of sodium hypochlorite |
| CN103290428A (en) * | 2013-06-17 | 2013-09-11 | 广西大学 | Closed cycle pollution-free sodium chlorate production process |
| CN103754828A (en) * | 2013-12-23 | 2014-04-30 | 内蒙古工业大学 | Sodium dichromate closed circulation clean production method for preparing sodium chlorate |
| CN106591876A (en) * | 2016-12-20 | 2017-04-26 | 四川岷江雪盐化有限公司 | Method for preparing sodium chlorate from industrial salt |
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-
1987
- 1987-03-27 CN CN 87102396 patent/CN1012441B/en not_active Expired
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101787541B (en) * | 2010-01-26 | 2011-08-17 | 四川金路集团股份有限公司 | Method for removing nitrates through CIM membrane method |
| CN101922014A (en) * | 2010-08-17 | 2010-12-22 | 刘亨益 | Diaphragm process chlorine generator and preparation method of sodium hypochlorite |
| CN102465311A (en) * | 2010-11-19 | 2012-05-23 | 中国水利水电科学研究院 | Preparing system and method of sodium hypochlorite |
| CN102465311B (en) * | 2010-11-19 | 2015-06-10 | 中国水利水电科学研究院 | Preparing system and method of sodium hypochlorite |
| CN103290428A (en) * | 2013-06-17 | 2013-09-11 | 广西大学 | Closed cycle pollution-free sodium chlorate production process |
| CN103290428B (en) * | 2013-06-17 | 2015-07-01 | 广西大学 | Closed cycle pollution-free sodium chlorate production process |
| CN103754828A (en) * | 2013-12-23 | 2014-04-30 | 内蒙古工业大学 | Sodium dichromate closed circulation clean production method for preparing sodium chlorate |
| CN106591876A (en) * | 2016-12-20 | 2017-04-26 | 四川岷江雪盐化有限公司 | Method for preparing sodium chlorate from industrial salt |
| CN106591876B (en) * | 2016-12-20 | 2019-04-02 | 四川岷江雪盐化有限公司 | A method of sodium chlorate is prepared by Nacl |
| CN107840309A (en) * | 2017-11-16 | 2018-03-27 | 四川岷江雪盐化有限公司 | A kind of method of three sections of continuous low temperature vacuum evaporating crystalizations production different-grain diameter chlorate |
| CN107840309B (en) * | 2017-11-16 | 2020-07-28 | 四川岷江雪盐化有限公司 | Method for producing chlorate with different particle sizes by three-stage continuous low-temperature vacuum evaporation crystallization |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1012441B (en) | 1991-04-24 |
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