CN103588225A - Method for producing food-grade potassium chloride through multistage flash evaporation, cooling and continuous crystallization - Google Patents

Abstract

The invention discloses a method for producing food-grade potassium chloride through multistage flash evaporation, cooling and continuous crystallization. The method comprises the following steps: 1) putting potassium chloride into a solution, heating to 100-110 DEG C to form a potassium chloride saturated solution I, 2) sequentially adding alkali and a purifier into the potassium chloride saturated solution I for heat preservation sedimentation, 3) filtering supernate obtained in Step 2), neutralizing with hydrochloric acid to be neutral, 4) pumping a potassium chloride saturated solution II to a single-effect flash evaporation crystallizer for flash evaporation, cooling and concentration, 5) conveying potassium chloride slurry I to a double-effect flash evaporation crystallizer for flash evaporation, cooling and the concentration with a forced circulation pump, 6) conveying potassium chloride slurry II to a triple-effect flash evaporation crystallizer for flash evaporation, cooling and concentration with another forced circulation pump, 7) separating potassium chloride slurry III with a centrifuge to form a potassium chloride wet product and a potassium chloride mother solution I, and 8) drying and packaging the potassium chloride wet product to form food-grade potassium chloride.

Description

The method that multistage flash evaporation cooling continuous crystallisation is produced food-grade potassium chloride

Technical field

The technology of the present invention belongs to inorganic salt evaporative crystallization field, relates to a kind of production technique of refined potassium chloride, the technique that particularly a kind of multistage flash evaporation cooling continuous crystallisation is produced food-grade potassium chloride.

Background technology

Repone K is colourless elongated rhombus or cubic system or white crystals small-particle, is mainly used in inorganic industry, is to manufacture various sylvite as the basic raw material of potassium hydroxide, vitriolate of tartar, saltpetre, Potcrate, arsenic potassium etc.; Dyestuffs industries is for the production of G salt and reactive dyestuffs; In agricultural, be a kind of important potash fertilizer; Also for muzzle or gun muzzle anti-inflammatory, iron and steel thermal treatment, also for electroplating and photograph industry.Mouthfeel and the sodium-chlor of Repone K are close, be commonly used for the additive of Cardia Salt or mineral water, pharmaceutically Repone K is as electrolyte balance regulating, the hypokalemia that is used for the treatment of and prevents a variety of causes to cause, also can be used for taking place frequently property, polyphyly premature beat or quick heart disorder that the poisoning by cardiotonic glycoside such as the heart, renal edema and purple foxglove cause.

For a long time, China's sylvite is all to rely on import to meet domestic demand, China's Potash Industry is produced the development of growing out of nothing through 50 years, last century, the nineties, the later stage was accelerated paces, under the support of national policy, the operation of in succession setting up the project of a collection of emphasis sylvite project, successively builds up 1,000,000 tons, Qinghai potash fertilizer engineering, Lop Nur " sieve potassium is thrown by state " 1,200,000 tons and sieve potassium second phase 1,800,000 tons of sylvite engineerings etc.Take now the Cha Er sweat salt lake of Chaidamu Basin, Qinghai Province, the output zone that salt lake, Lop Nur, Xinjiang is main sylvite, 2010 Qinghai salt lake industrial group sylvite turnout reach 2,130,000 tons, 1,170,000 tons of other manufacturing enterprise's sylvite.

The fast development of China's sylvite industry, the contradiction that makes sylvite short-term lack supply is being resolved gradually.There are at present the ,Hai Xi of QingHai YanHu Industry Group Co., Ltd state tripotassium Gui Ye company limited of Air China, development in science and technology company limited of CITIC Guoan, Qinghai Province shoreland potash fertilizer limited-liability company, Golmud Deng30 many enterprises of Zang Ge potash fertilizer company limited to be engaged in sylvite and produce, will form the throughput of 4,500,000 tons of left and right.China is outside strengthening the exploitation dynamics of domestic sylvite, also strengthen the paces of oversea exploitation sylvite simultaneously, the existing 3 company's experimental projects of four Chinese Enterprise at Laos's investment material put into operation at present, form the most at last the throughput of producing 6000000 tons per year, add that other enterprise is at the potash project of building overseas, develop sylvite project accumulative total production capacity overseas and will reach 8,000,000 tons, these projects are built up rear domestic and international accumulative total annual output, by reaching 2000 Wan Dun， China, the potash fertilizer main body entrance state by present are suddenly become to export State.

Because China starts late to aspects such as the derivative new variety researchs of the product development of sylvite, technical equipment, Application Areas and sylvite, the aspects such as equipment technology, production cost and quality product are compared or have very large gap with external sylvite developed country, higher-grade Potassium Chloride Product particularly, all there are many problems in domestic production technology and quality product.How by sylvite big country, to change China into sylvite and make the country prosperous, also need to go effort from production technique, technical equipment, quality product and new varieties etc., the pair that improves Potassium Chloride Product is value added.

Along with the raising of people's living standard, need to be increasing for higher-grade refined potassium chloride, particularly food grade and pharmaceutical grade Repone K, current domestic edible potassium chloride annual production is 200,000 tons of left and right, and future 10 annual requirements will reach 300,000 tons.The gordian technique of the higher-grade KCl productions such as food grade and pharmaceutical grade Repone K is exactly how to reduce production costs, improve the quality of products and stability.The production technique of producing at present edible potassium chloride is both at home and abroad to continue to use the evaporative crystallization technique of the nineties in last century substantially, and its technique generally comprises dissolving, removal of impurities, crystallization, filtration and oven dry.Although this method can be produced the Repone K conforming to quality requirements, production cost is high, and energy consumption is high, can not serialization production cause yielding poorly, and Repone K crystalline particle is little and inhomogeneous, and easily caking hardens.

Open statement in the Chinese invention patent " production technique of medicinal potassium chloride " (201010556232.7) of the application such as the Gu little Qiang of the diligent pharmaceutcal corporation, Ltd in Jiangsu, raw material Repone K is added to the water, steam heating is dissolved, the barium sulfate precipitate that adds slightly excessive barium chloride solution sulfate radical to be converted into indissoluble is removed by filtering, adding potassium hydroxide that iron is converted into ferric hydroxide precipitate removes, add salt of wormwood that calcium and magnesium ion and excessive barium ion are generated respectively to corresponding carbonate deposition and remove, solution after filtration neutralizes and is slightly acidic with hydrochloric acid, clear liquid adopts two effect evaporations to concentrate, after crystallisation by cooling again by centrifugation, dry and packing obtains finished product.The Repone K quality that adopts this technology to produce is good, but technical process is long, and particularly Repone K impurity removal process very complex, adds that it adopts two effect evaporating and concentrating process, and production energy consumption is higher.Because this production technique is at high temperature to carry out crystallization, Repone K crystallization is poor, and product easily caking hardens, and has to add chemical anti-hard caking agent to delay caking in product, causes the application of its product to be restricted.

The Chinese invention patent of the applications such as the Zhang Peilin of Haijing Group Co., Ltd., Changlu, Tianjin City clearly openly adopts a kind of dual circulation method to produce the method for edible potassium chloride in " by the method for dual circulation method production edible potassium chloride " (201110146158.6), it comprises the following steps: technical grade Repone K is carried out in dissolver to high-temperature digestion, Repone K solubility after dissolving is 35.9-36.4 degree Beaume, and temperature is 100-105 ℃; Klorvess Liquid after high-temperature digestion is filtered to filtering accuracy≤5 micron; Klorvess Liquid after filtering is pumped into one section of vaporizer and carry out one section of evaporation concentration, the temperature of Klorvess Liquid is 92-97 ℃, and concentration is 35.9-36.4 degree Beaume, and the vacuum tightness in vaporizer is 78-83Kp; Klorvess Liquid through one section of evaporation is pumped into flash evaporator, and to carry out flash evaporator concentrated, and vacuum tightness is 90-95Kp, uses steam heating flash evaporator, makes temperature rise to 35-40 ℃; One section of feed liquid obtaining with dual circulation is pumped into whizzer and dewater, the potassium chloride after dehydration is dried under 125-130 ℃ of condition.The method adopts stage evaporation technique, first paragraph is flash vaporization, second segment is vacuum-evaporation, for continuously feeding evaporation, has realized serialization and has uninterruptedly produced, compare with known existing production technology, there is improvement to a certain degree, than 1.3 tons of 1 ton of Repone K steam savings of the every production of known conventional technology, save 2 tons, water, but because its dual circulation still adopts conventional evaporation concentration technique, energy consumption is relatively high; The product that carries out crystallization under hot conditions easily lumps and hardens; In one section of evaporation and dual circulation process, crystallization respectively, causes unstable product quality also inhomogeneous.

The Chinese invention patent " a kind of production method of high-quality potassium chloride " (201110122545.6) of the Yan Xin equality application of Tangshan Huixin Jiade Energy Saving and Emission Reduction Technology Co., Ltd. has been set forth a kind of production method of high-quality potassium chloride, vat liquor containing potassium dust is preheated to 110-130 ℃, successively through an effect evaporation, two effect evaporation and triple effect evaporations, triple effect evaporation completes liquid after quadruple effect evaporation, obtain industrial Potassium Chloride Product, quadruple effect complete evaporation of liquid and mixing condensation water return to the lixiviate of lixiviate operation containing potassium dust, realize recycle.What in this process using steel smelting procedure, produce contains potassium dust as main raw material(s), by quadruple effect evaporation concentration, produces high-quality Repone K, for the utilization containing potassium trade waste, has opened up an approach, has realized the object of energy-saving and emission-reduction and recycling economy.Its evaporative process has also been illustrated in this invention, and the secondary steam that utilizes quadruple effect evaporator to produce carries out preheating as thermal source to stock liquid, be to be significantly improved, but facility investment is large from steam saving, and the energy consumption that material transmits operation is high, poor product quality.

Lianyun Harbour open narration in the Chinese invention patent of wishing the applications such as Guilin " a kind of energy-saving technique of producing the fertile potassium of edible chlorine " (201110070362.4) of Kechuang foodstuff additive company limited of rearing people: the Klorvess Liquid after dissolving removal of impurities enters preheater and carries out preheating, the material of being come by mother liquor and the preheater of draft tube baffle crystallizer overflow converges the conveying by forced circulation pump, enter into heating fumigators, after heating fumigators heating absorption heat heats up, enter draft tube baffle crystallizer intercrystalline, utilize the conveying of magma pump, magma is sent to whizzer and carries out separation, obtain potassium chloride, by draft tube baffle crystallizer secondary steam out, by vapour compressor, compress and send into heating fumigators after heating up material is carried out to indirect heating, condensed water enters collector preheating for preheater.The method of this invention is that a kind of single-effect evaporation adds continuous crystallisation technique in particular, although this processing method has increased vapour compression recycling step, evaporation energy consumption decreases, and it is single-effect evaporation, and energy consumption is still high than multiple-effect evaporation.Because Repone K is to dissolve at normal temperatures, in its saturated solution, the concentration of Repone K is lower, and need to evaporate a large amount of moisture content could crystallization go out Repone K, so steam consumption is high.Due to its at high temperature crystallization (secondary steam temperature is 90 ℃), product cut size is little, and easily caking hardens.

The Chinese invention patent " by the method for preparing pharmaceutical grade potassium chloride with sea salt potassium chloride " (201010181733.1) of the applications such as the great space of Lianyungang Design and Research Institute (Lanai Engineering Co.) woods discloses a kind of method of producing medical Repone K with potassium chloride with sea salt: by potassium chloride with sea salt be crushed to loose after and circulating mother liquor, secondary washing liquid be added in proportion in crystallizer, make material in crystallizer reaction zone be complete mixing flow state, under the stable prerequisite of guarantee system, discharge crystallizer underflow, crystallizer underflow obtains time product and first-time filtrate through centrifugation; Again first product, saturated potassium chloride solution, secondary washing liquid are added in proportion in steel basin and carries out pulp washing, centrifugation obtains second product and secondary washing liquid; Second product, saturated potassium chloride solution, deionized water are added in proportion in steel basin and carry out pulp washing, and centrifugation obtains pharmaceutical grade Repone K and saturated potassium chloride solution.This inventive method has been removed the shortcoming of high energy consumption in traditional potassium chloride production process from, but because Repone K in its whole production process is all less than the process of all dissolving, Klorvess Liquid can not get filtering and impurity removing, therefore the clarity of products obtained therefrom is poor, mechanical impurity is many, and operation steps is loaded down with trivial details, there is no too large practical application meaning.

A kind of production technique of high-purity potassium chloride is disclosed in the Chinese invention patent " a kind of production technique of high-purity potassium chloride " (200510124224.4) of the applications such as high Song credit, take purity as the Repone K below 98% be raw material, by Repone K soluble in water saturated solution I; Saturated potassium chloride solution I, by sedimentation or filtration, is removed to the saturated clear liquid II that insolubles obtains Repone K; The saturated clear liquid II of Repone K, by evaporation concentration, until there is crystal to separate out, is made Repone K supersaturated solution III; Supersaturated solution III, through filtering and impurity removing, makes the Repone K supersaturated solution IV without solid insoluble; Repone K supersaturated solution IV is cooled to-6 ℃～-6.5 ℃ crystallizations, obtains crystalline potassium chloride and mother liquor mixture, through centrifugation, obtains potassium chloride and mother liquor V; Potassium chloride is with obtaining purity at more than 99% Repone K after pure water washing.This patent of invention method utilizes the otherness of Repone K solubleness under differing temps to carry out Crystallization Separation, there is process simple, the advantages such as facility investment is few, but owing to adopting conventional evaporation concentration, steam consumption is too high, need to be cooled to-6 ℃～-6.5 ℃ and carry out crystallization, powerful refrigeration equipment to realize.

The Chinese invention patent " production process of refined potassium chloride " (201010533173.1) of the Liu Li equality application of Tianjin Changlu Hangu Saltern Co., Ltd discloses a kind of production process of refined potassium chloride, it is more than 97% technique that the Repone K that soon content will be 90% is refined into food-grade potassium chloride content, comprise the steps: in saturated potassium chloride solution (or circulation fluid), to add under room temperature 90% Repone K, form supersaturated solution; Supersaturated solution, after coarse filter filters, is heated to 100-105 ℃, and Repone K all dissolves; High temperature saturated solution, after hot-water filter filters, obtains refining saturated solution; Refining saturated solution is through vacuum cooling crystallizer crystallisation by cooling, then through centrifuge dewatering, drying bed obtains purified diet grade potassium chloride after being dried, and the mother liquor that whizzer is deviate from is as circulation fluid retrieval system.The Repone K impurity that method described in this patent of invention prepares is high, and this technique is the typical cooling and crystallizing process that dissolves, in crystallisation process, there is no evaporative process, cause the disposable yield of Potassium Chloride Product low, production capacity is restricted, and produce for discontinuity, quality product is difficult to reach the requirement that food-grade potassium chloride is produced.

The grandson Zhang Fu of salinization factory of Liaoning Yingkou Saltworks etc. produce purified salt > > in < < sea salt lake and the 3-13 page of the chemical industry > > magazine third phase < < application multiple-effect flash evaporation recrystallize method that publishes thesis, and the said firm produces the technology and equipment of purified salt from a set of multiple-effect flash evaporation of external introduction recrystallize method.Crude salt after by pre-treatment hot clear saturated bittern, by being pumped in the circulation tube of I effect flash evaporation crystallizer, enter flash chamber with circulation bittern mixture, by the crystallization of flash evaporation precipitated sodium chloride, and sink in the salt leg of base of evaporator, after bittern countercurrent washing, be regularly discharged in salt slurry tank.Mother liquor is inhaled into recycle pump, the flash evaporation of proceeding to circulate after mixing with the clear saturated bittern of the heat adding operation.Mother liquor after the evaporation of I effect is entered in II effect by weir tank, and I effect double evaporation-cooling vapour removes warm Brine pre-heater direct heating bittern, in like manner, carries out the cyclical operation of II effect flash evaporation.Mother liquor after the evaporation of II effect is entered in III effect by weir tank, and II effect secondary steam removes low temperature Brine pre-heater direct heating bittern, in like manner, carries out the cyclical operation of III effect flash evaporation.Finally, the mother liquor after the evaporation of III effect is entered in mother liquor tank by weir tank, as next circulating mother liquor, uses.III effect secondary steam removes vapour liquid separator, then through water spray and steam, with water coolant, makes vapor condensation, and the water coolant of heat goes water cooling tower to recycle, and non-condensable gas is got rid of by steam and formed condition of high vacuum degree.The salt slurry of discharging from three flash evaporation advections is mixture salt slurry tank, with being pumped into thickener, in this solid phase sedimentation thickening.When the circulating mother liquor of discharging from III effect, impurity magnesium chloride, sal epsom equal size surpass specified amount, must discharge a system part with pump, another part removes to do after bittern filter cleaning washing bittern and discharges the mother liquor amount of system and decide according to foreign matter content in circulating mother liquor.Most circulating mother liquor adds 20% sodium hydroxide solution quantitatively, after the pH value of adjustment mother liquor is 8, and the closed-cycle operation of participating in next mother liquor.In the method, use conventional flasher, every effect all by sodium-chlor Crystallization Separation out, finally just mixes triple effect and carries out stiff separation.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of method that multistage flash evaporation cooling continuous crystallisation is produced food-grade potassium chloride.

In order to solve the problems of the technologies described above, the invention provides a kind of method that multistage flash evaporation cooling continuous crystallisation is produced food-grade potassium chloride, in turn include the following steps:

1), by content (weight content) for >=96% Repone K drops in solution and is heated to 100～110 ℃, obtain 100～110 ℃ of saturated potassium chloride solution I at temperature;

Described solution is the Repone K mother liquor I after the preheating of tap water or following step 7) gained;

Remarks explanation: when initial, use tap water; Then all can use the Repone K mother liquor I after the preheating of step 7) gained, if Repone K mother liquor I is not enough, need supply with tap water;

2), in saturated potassium chloride solution I, add successively alkali and cleaner, be incubated (100～110 ℃) sedimentation, the insulation settling time is 1～3 hour; The add-on of described alkali is for regulating pH to 12 ± 0.2 of saturated potassium chloride solution I;

Described cleaner is comprised of calcium oxide, ammonium chloride and composition A; Described composition A is at least one in phosphoric acid, potassium primary phosphate and Secondary ammonium phosphate;

The addition of described calcium oxide is that 0.04～0.12%(of the Repone K quality in saturated potassium chloride solution I is preferably 0.1%);

The addition of described ammonium chloride is that 0.06%～0.24%(of the Repone K quality in saturated potassium chloride solution I is preferably 0.12%～0.24%);

The addition of described composition A is that 0.16%～0.72%(of the Repone K quality in saturated potassium chloride solution I is preferably 0.3%～0.72%);

3), at 100～110 ℃, by step 2) supernatant liquor of gained is incubated filtration (object of filtration is in order to remove insoluble substance) by cartridge filter, the filtrate of filtering gained is neutralized to neutrality with hydrochloric acid and (that is, Ph=7), obtains saturated potassium chloride solution II;

4), by pump delivery to I effect flash evaporation crystallizer, to carry out flash distillation cooling concentrated for saturated potassium chloride solution II; Processing parameter is as follows:

Temperature is controlled at 76～80 ℃, and vacuum degree control is at-0.080Mpa～-0.086Mpa, circular flow be I effect flash evaporation crystallizer material amount 0.5～1 volume doubly/hour;

Until the Repone K slurry I of gained contains the potassium chloride that accounts for Repone K slurry I gross weight 3.5～5%;

5), Repone K slurry I is transported to II effect flash evaporation crystallizer by forced circulation pump to carry out flash distillation cooling concentrated, processing parameter is as follows:

Temperature is controlled at 48～52 ℃, and vacuum degree control is at-0.094Mpa～-0.096Mpa, circular flow be II effect flash evaporation crystallizer material amount 0.5～-1 volume doubly/hour;

Until the Repone K slurry II of gained contains the potassium chloride that accounts for Repone K slurry II gross weight 9.5～11%;

6), Repone K slurry II is transported to III effect flash evaporation crystallizer by another forced circulation pump to carry out flash distillation cooling concentrated, processing parameter is as follows:

Temperature is controlled at 18～22 ℃, and vacuum degree control is at-0.098Mpa～-0.099Mpa, circular flow be III effect flash evaporation crystallizer material amount 0.5～1 volume doubly/hour;

Until the Repone K slurry III of gained contains the potassium chloride that accounts for Repone K slurry III gross weight 15～16.5%;

7), Repone K slurry III carries out separation (centrifugal rotational speed is 1000～1200 revs/min, and the time is 8～12 minutes) by whizzer, obtains Repone K wet product and Repone K mother liquor I;

Repone K mother liquor I is moved out of food-grade potassium chloride production line with 5～10% volume ratios (per hour), as the stock liquid of production agricultural grade Repone K or as the raw material of producing saleratus;

The secondary steam that remaining Repone K mother liquor I utilizes II effect flash evaporation crystallizer and I effect flash evaporation crystallizer to produce successively carries out preheating, thereby return to step 1), as solution, uses;

8), packing after Repone K wet product dry (drying temperature is 120～130 ℃, until dried Repone K water content is less than 0.1%), obtain food-grade potassium chloride.

As multistage flash evaporation cooling continuous crystallisation of the present invention, produce the improvement of the method for food-grade potassium chloride:

When Repone K mother liquor I after the preheating of step 7) gained is in shortage as the solution in step 1), with tap water, supply.

The further improvements in methods of producing food-grade potassium chloride as multistage flash evaporation cooling continuous crystallisation of the present invention: alkali described step 2) is potassium hydroxide;

Cartridge filter in described step 3) is the cartridge filter with heat-insulating property, and material is titanium material, and aperture is 5 microns.

The further improvements in methods of producing food-grade potassium chloride as multistage flash evaporation cooling continuous crystallisation of the present invention: described I effect flash evaporation crystallizer, II effect flash evaporation crystallizer, III effect flash evaporation crystallizer are DTB type crystallizer.

Remarks explanation:

Steam is exactly the raw steam that boiler is come first, and secondary steam just refers in evaporative process, and material passes through raw steam heating, the steam producing after material boiling;

The Btu utilization mode of I effect flash evaporation crystallizer, II effect flash evaporation crystallizer is as described below:

The secondary steam producing is taken out solidifying by steam-jet compression pump, what be used for step 7) carries out preheating to described remaining Repone K mother liquor I, heat is after being used, tail gas is taken away through vertical pipe type condenser water circulation vacuum pump, and the steam condensate of formation can be used as pure water and returns to boiler or production process recycling; Steam-jet compression pump adopts the steam that comes from boiler to extract secondary steam as power.

The secondary steam that III effect flash evaporation crystallizer produces is taken out solidifying by steam-jet compression pump, tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling; The steam condensate forming can be used as pure water and returns to boiler or production process recycling; Steam-jet compression pump adopts the steam that comes from boiler to extract secondary steam as power;

Because the flash vaporization point of III effect flash evaporation crystallizer is too low, therefore cannot be reused.

The further improvements in methods of producing food-grade potassium chloride as multistage flash evaporation cooling continuous crystallisation of the present invention:

On the vapour liquid separator top duct of described I effect flash evaporation crystallizer, II effect flash evaporation crystallizer and III effect flash evaporation crystallizer, install ammonium chloride evaporation gas washing apparatus (patent No. CN200620101864.3) additional, guarantee not contain in secondary steam Repone K.The steam condensate producing returns to boiler, has solved the problem of boiler feed water.

The further improvements in methods of producing food-grade potassium chloride as multistage flash evaporation cooling continuous crystallisation of the present invention:

Vapor pressure 0.9～1.1Mpa(that the steam-jet compression pump of the III effect flash evaporation crystallizer using in the II effect flash evaporation crystallizer using in the I effect flash evaporation crystallizer using in described step 4), step 5), step 6) is selected is for example 1.0Mpa).

The further improvements in methods of producing food-grade potassium chloride as multistage flash evaporation cooling continuous crystallisation of the present invention:

Being dried of described step 8), adopts vibrated fluidized bed to carry out.

The further improvements in methods of producing food-grade potassium chloride as multistage flash evaporation cooling continuous crystallisation of the present invention:

In described step 7):

The secondary steam that remaining ammonium chloride mother liquor I utilizes II effect flash evaporation crystallizer and I effect flash evaporation crystallizer to produce successively carries out preheating, temperature by 20 ℃ rise to >=50 ℃.

In the present invention, the secondary steam producing through II effect flash evaporation crystallizer and I effect flash evaporation crystallizer successively described in step 7) carries out Repone K mother liquor I after preheating when in shortage as the solution in step 1), with tap water, supplies.

The present invention is by regulating step 4), temperature, vacuum tightness and the solid circulating rate of material in step 5) and step 6) crystallizer, realized Repone K crystallization particle diameter and quality controlled.

The present invention compares with common process, adopt three grades of flash distillation continuous cooling crystallizations to produce food-grade potassium chlorides and have that energy consumption is low (to be compared with existing production technique, can steam saving more than 20%), controlled (Repone K granularity can be controlled in 0.7-1.0mm to constant product quality, uniform particles, smooth surface) and totally-enclosed serialization produce advantages such as (more easily meeting foodstuff production standard).By steam-jet compression pump, extract the secondary steam of I effect flash evaporation crystallizer and the generation of II effect flash evaporation crystallizer as the preheating of Repone K mother liquor I, can save a large amount of steam, adopt steam-jet compression pump Refrigeration Technique, make III effect flash crystallization actuator temperature be reduced to 18～22 ℃, greatly improve Repone K crystal property, avoid the interpolation of caking and the chemical anti-hard caking agent of Potassium Chloride Product.Selecting pressure is that 0.9～1.1Mpa(is preferably 1.0Mpa) steam by steam-jet compression pump, extract the secondary steam that III effect flash evaporation crystallizer produces, can save 20% above steam.By temperature, vacuum tightness and the solid circulating rate of material in regulating step (4), step (5) and step (6) crystallizer, realize carbon Repone K crystallization particle diameter and quality are controlled.The method that multistage flash evaporation cooling continuous crystallisation of the present invention is produced food-grade potassium chloride is a kind of green production technique, has both reduced energy consumption, improves again quality product, reduces environmental pollution simultaneously, is worth large-scale promotion application.

According to the regulation of GB25585-2010: the condition that food-grade potassium chloride need to be satisfied is specific as follows: KCE content >=99.0%, pH value is by test, iodine with bromine by test, arsenic≤0.0002%, heavy metal≤0.0005%, weight loss on drying≤1.0%, sodium≤0.5%.The food-grade potassium chloride of gained of the present invention meets above-mentioned requirements completely.

Embodiment

Remarks explanation: in following examples, on the vapour liquid separator top duct of I effect flash evaporation crystallizer, II effect flash evaporation crystallizer and III effect flash evaporation crystallizer, install ammonium chloride evaporation gas washing apparatus (patent No. CN200620101864.3) additional, guarantee not contain in secondary steam Repone K.The steam condensate producing returns to boiler, has solved the problem of boiler feed water.

The method that embodiment 1-1, a kind of multistage flash evaporation cooling continuous crystallisation are produced food-grade potassium chloride, carry out successively following steps:

1) Repone K that is, 96.5% by 6170 kilograms of content drops into 11m ³in tap water, be mixed with Repone K supersaturated solution, be heated to 110 ℃ (under agitation in chuck, passing into steam), after potassium chloride dissolves, obtain saturated potassium chloride solution I, in the saturated potassium chloride solution I of gained, contain altogether the Repone K of 5950kg;

2), whole saturated potassium chloride solution I (about 14.4m of past above-mentioned step 1) gained ³) in first add 48 kilograms of potassium hydroxide, thereby regulate the pH value of saturated potassium chloride solution I to reach 12, then add 6.2 kilograms of stirring and dissolving of calcium oxide, add respectively again 11 kilograms of ammonium chlorides and 30 kilograms of potassium primary phosphates, after stirring 30min, at 100-110 ℃ of temperature, be incubated sedimentation, the insulation settling time is 2 hours; Saturated potassium chloride solution I, by being incubated after sedimentation, obtains supernatant liquor;

3), at 100-110 ℃, by step 2) supernatant liquor of gained is 5 microns by aperture the cartridge filter with heat-insulating property filters, the saturated potassium chloride solution (filtering the filtrate of gained) of removing after insoluble substance is neutralized to neutrality with hydrochloric acid, (suspended substance is less than 0.5mg/l to obtain saturated potassium chloride solution II, potassium chloride concentration is 35.6%, Ca2+:0.0001%, Mg2+:0.0001%, Fe≤0.00005%, heavy metal≤0.00005%).

4), by temperature, be the saturated potassium chloride solution II of 100-110 ℃ by take away pump with 14m per hour ³the flow I effect flash evaporation crystallizer that is delivered to DTB type to carry out flash distillation cooling concentrated.In I effect flash evaporation crystallizer, the temperature of material is controlled at 76-80 ℃, vacuum degree control adopts vapor pressure 1.0Mpa steam-jet compression pump at-0.080Mpa～-0.086Mpa(while vacuumizing, the mixing steam producing is as the preheating that remains Repone K mother liquor I described in step 7), tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling), the circular flow of material be Repone K slurry in crystallizer (being I effect flash evaporation crystallizer material amount) 1 times of volume/hour, until the Repone K slurry I of gained contains the potassium chloride that accounts for Repone K slurry I gross weight 4.2%,

5), Repone K slurry I is transported to DTB type II effect flash evaporation crystallizer by slurries formula forced circulation pump and carries out flash concentration cooling, in II effect flash evaporation crystallizer, temperature of charge is controlled at 48-52 ℃, vacuum degree control adopts vapor pressure 1.0Mpa steam-jet compression pump at-0.094Mpa～-0.096Mpa(while vacuumizing, the mixing steam producing is as the preheating that remains Repone K mother liquor I described in step 7), tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling), the circular flow of material be Repone K slurry in crystallizer (being II effect flash evaporation crystallizer material amount) 1 times of volume/hour, until the Repone K slurry II of gained contains the potassium chloride that accounts for Repone K slurry II gross weight 10.3%.

6), Repone K slurry II is transported to DTB type III effect flash evaporation crystallizer by slurries formula forced circulation pump and carries out flash distillation decrease temperature crystalline, in III effect flash evaporation crystallizer, temperature of charge is controlled at 18-22 ℃, vacuum degree control adopts vapor pressure 1.0Mpa steam-jet compression pump at-0.098Mpa～-0.099Mpa(while vacuumizing, tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling), the circular flow of material be Repone K slurry in crystallizer (being III effect flash evaporation crystallizer material amount) 1 times of volume/hour, until the Repone K slurry III of gained contains the potassium chloride that accounts for Repone K slurry III gross weight 15.8%.

7), Repone K slurry III is by centrifugation (centrifugal rotational speed is 1200 revs/min, and the time is 10 minutes), obtains the Repone K wet product that 2770 kilograms of water content are 2.8%, temperature is the Repone K mother liquor I 11m altogether of 20 ℃ ³, 10%(11m wherein ³* 10%=1.1m3) Repone K mother liquor I shifts out food-grade potassium chloride crystal system production line, remaining 90%(11m ³* 90.0% ≈ 9.9m ³) the Repone K mother liquor I secondary steam that utilizes successively II effect flash evaporation crystallizer and I effect flash evaporation crystallizer to produce carry out preheating, temperature rises to 50 ℃ by 20 ℃, returns to step (1) and dissolves raw material Repone K (can be used as solution uses).

8) the Repone K wet product that is, 2.8% by 2770 kilograms of water content of centrifugal gained is by vibra fluidized bed drying (temperature during vibra fluidized bed drying is 125 ℃), cross 40 eye mesh screens, obtain 2688 kilograms of food-grade potassium chloride finished products, KCE content is 99.7%, sodium chloride content is 0.22%, and calcium magnesium is all less than 0.0001%, and heavy metal and arsenic are all less than 1ppm, water content is 0.1%, and median size is 0.9mm.

In the present embodiment, dissolve insulating process and consume altogether 1980 kilograms of steam, 2320 kilograms of flash cooling crystallisation process consumption steam, 820 kilograms of drying process consumption steam, folding steam mono-consumption is 1905 kgs/tonne of Repone K.

The method that embodiment 1-2, a kind of multistage flash evaporation cooling continuous crystallisation are produced food-grade potassium chloride, carry out successively following steps:

1) Repone K that is, 96.5% by 3280 kilograms of content drops into the 10m through preheating (temperature is 50-52 ℃) ³repone K mother liquor I and 1.5m ³in tap water, be mixed with Repone K supersaturated solution, be heated to 110 ℃ (under agitation in chuck, passing into steam), after potassium chloride dissolves, obtain saturated potassium chloride solution I, in the saturated potassium chloride solution I of gained, contain altogether the Repone K of 6050kg;

2), in whole saturated potassium chloride solution I of above-mentioned step 1) gained, first add potassium hydroxide, until regulate the pH value of saturated potassium chloride solution I to reach 12, then add 3.3 kilograms of stirring and dissolving of calcium oxide, add respectively again 6 kilograms of ammonium chlorides and 16 kilograms of potassium primary phosphates, after stirring 30min, at 100-110 ℃ of temperature, be incubated sedimentation, the insulation settling time is 2 hours; Saturated potassium chloride solution I, by being incubated after sedimentation, obtains supernatant liquor;

3), at 100-110 ℃, by step 2) supernatant liquor of gained is 5 microns by aperture the cartridge filter with heat-insulating property filters, the saturated potassium chloride solution (filtering the filtrate of gained) of removing after insoluble substance is neutralized to neutrality with hydrochloric acid, (suspended substance is less than 0.5mg/l to obtain saturated potassium chloride solution II, potassium chloride concentration is 35.4%, Ca2+:0.0001%, Mg2+:0.0001%, Fe≤0.00005%, heavy metal≤0.00005%).

4), step 4)～8) with embodiment 1-1.

Final 2708 kilograms of food-grade potassium chloride finished products, KCE content is 99.6%, and sodium chloride content is 0.28%, and calcium magnesium is all less than 0.0001%, and heavy metal and arsenic are all less than 1ppm, and water content is 0.12%, and median size is 0.8mm.

In the present embodiment, dissolve insulating process and consume altogether 1280 kilograms of steam, 2240 kilograms of flash cooling crystallisation process consumption steam, 840 kilograms of drying process consumption steam, folding steam mono-consumption is 1610 kgs/tonne of Repone K.

Embodiment 2: a kind of method that multistage flash evaporation cooling continuous crystallisation is produced food-grade potassium chloride, carry out successively following steps:

1) Repone K that is, 96.5% by 3120 kilograms of content drops into the 10.5m through preheating (temperature is 50-52 ℃) ³repone K mother liquor I and 1m ³in tap water, be mixed with Repone K supersaturated solution, be heated to 110 ℃ (under agitation in chuck, passing into steam), after potassium chloride dissolves, obtain saturated potassium chloride solution I, in the saturated potassium chloride solution I of gained, contain altogether the Repone K of 6030kg;

2), in above-mentioned whole saturated potassium chloride solution I, first add potassium hydroxide, until regulate the pH value of saturated potassium chloride solution I to reach 12, then add 3.1 kilograms of stirring and dissolving of calcium oxide, add respectively again 6 kilograms of ammonium chlorides and 16 kilograms of potassium primary phosphates, after stirring 30min, at 100-110 ℃ of temperature, be incubated sedimentation, the insulation settling time is 2 hours; Saturated potassium chloride solution I, by being incubated after sedimentation, obtains supernatant liquor;

3), by step 2) supernatant liquor of gained is 5 microns by aperture the cartridge filter with heat-insulating property filters, the saturated potassium chloride solution (filtering the filtrate of gained) of removing after insoluble substance is neutralized to neutrality with hydrochloric acid, (suspended substance is less than 0.5mg/l to obtain saturated potassium chloride solution II, potassium chloride concentration is 36.5%, Ca2+:0.0001%, Mg2+:0.0001%, Fe≤0.00005%, heavy metal≤0.00005%).

4), by temperature, be the saturated potassium chloride solution II of 100-110 ℃ by take away pump with 14m per hour ³the flow I effect flash evaporation crystallizer that is delivered to DTB type to carry out flash distillation cooling concentrated.In I effect flash evaporation crystallizer, the temperature of material is controlled at 76-80 ℃, vacuum degree control adopts vapor pressure 1.0Mpa steam-jet compression pump at-0.080Mpa～-0.086Mpa(while vacuumizing, the mixing steam producing is as the preheating that remains Repone K mother liquor I described in step 7), tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling), the circular flow of material be Repone K slurry in crystallizer 1 times of volume/hour, until the Repone K slurry I of gained contains the potassium chloride that accounts for Repone K slurry I gross weight 4.6%;

5), Repone K slurry I is transported to DTB type II effect flash evaporation crystallizer by slurries formula forced circulation pump and carries out flash concentration cooling; In II effect flash evaporation crystallizer, temperature of charge is controlled at 48-52 ℃, vacuum degree control adopts vapor pressure 1.0Mpa steam-jet compression pump at-0.094Mpa～-0.096Mpa(while vacuumizing, the mixing steam producing is as the preheating that remains Repone K mother liquor I described in step 7), tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling), the circular flow of material be Repone K slurry in crystallizer 1 times of volume/hour, until the Repone K slurry II of gained contains the potassium chloride that accounts for Repone K slurry II gross weight 10.8%.

6), Repone K slurry II is transported to DTB type III effect flash evaporation crystallizer by slurries formula forced circulation pump and carries out flash distillation decrease temperature crystalline, in III effect flash evaporation crystallizer, temperature of charge is controlled at 18-22 ℃, vacuum degree control adopts vapor pressure 1.0Mpa steam-jet compression pump at-0.098Mpa～-0.099Mpa(while vacuumizing, tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling), the circular flow of material be Repone K slurry in crystallizer 1 times of volume/hour, until the Repone K slurry III of gained contains the potassium chloride that accounts for Repone K slurry III gross weight 16.2%.

7), Repone K slurry III is by centrifugation (centrifugal rotational speed is 1200 revs/min, and the time is 10 minutes), obtains the Repone K wet product that 2850 kilograms of water content are 3%, temperature is the Repone K mother liquor I 11m altogether of 20 ℃ ³, 5%(11m wherein ³* 5% ≈ 0.55m ³) Repone K mother liquor I shifts out food-grade potassium chloride crystal system production line, remaining 95%(11m ³* 95.0% ≈ 10.45m ³) the Repone K mother liquor I secondary steam that utilizes successively II effect flash evaporation crystallizer and I effect flash evaporation crystallizer to produce carry out preheating, temperature rises to 50 ℃ by 20 ℃, returns to step (1) and dissolves raw material Repone K.

8) the Repone K wet product that is, 2.8% by 2850 kilograms of water content of centrifugal gained is by vibra fluidized bed drying (temperature during vibra fluidized bed drying is 125 ℃), cross 40 eye mesh screens, obtain 2765 kilograms of food-grade potassium chloride finished products, KCE content is 99.5%, sodium chloride content is 0.42%, and calcium magnesium is all less than 0.0001%, and heavy metal and arsenic are all less than 1ppm, water content is 0.11%, and median size is 0.7mm.

In the present embodiment, dissolve insulating process and consume altogether 1010 kilograms of steam, 2210 kilograms of flash cooling crystallisation process consumption steam, 980 kilograms of drying process consumption steam, folding steam mono-consumption is 1519 kgs/tonne of Repone K.

The method that embodiment 3, a kind of multistage flash evaporation cooling continuous crystallisation are produced food-grade potassium chloride, carry out successively following steps:

1) Repone K that is, 96.5% by 2420 kilograms of content drops into the 12.5m through preheating (temperature is 50-52 ℃) ³in Repone K mother liquor I, be mixed with Repone K supersaturated solution, be heated to 110 ℃ (under agitation in chuck, passing into steam), after potassium chloride dissolves, obtain saturated potassium chloride solution I, in the saturated potassium chloride solution I of gained, contain altogether the Repone K of 6122kg.

2), in above-mentioned whole saturated potassium chloride solution I, first add potassium hydroxide, until regulate the pH value of saturated potassium chloride solution I to reach 12, then add 2.4 kilograms of stirring and dissolving of calcium oxide, add respectively again 4 kilograms of ammonium chlorides and 12 kilograms of potassium primary phosphates, after stirring 30min, at 100-110 ℃ of temperature, be incubated sedimentation, the insulation settling time is 2 hours; Saturated potassium chloride solution I, by being incubated after sedimentation, obtains supernatant liquor;

3), by step 2) supernatant liquor of gained is 5 microns by aperture the cartridge filter with heat-insulating property filters, the saturated potassium chloride solution (filtering the filtrate of gained) of removing after insoluble substance is neutralized to neutrality with hydrochloric acid, (suspended substance is less than 0.5mg/l to obtain saturated potassium chloride solution II, potassium chloride concentration is 36.4%, Ca2+:0.0001%, Mg2+:0.0001%, Fe≤0.00005%, heavy metal≤0.00005%).

4), by temperature, be the saturated potassium chloride solution II of 100-110 ℃ by take away pump with 14m per hour ³the flow I effect flash evaporation crystallizer that is delivered to DTB type to carry out flash distillation cooling concentrated.In I effect flash evaporation crystallizer, the temperature of material is controlled at 76-80 ℃, vacuum degree control adopts vapor pressure 1.0Mpa steam-jet compression pump at-0.080Mpa～-0.086Mpa(while vacuumizing, the mixing steam producing is as the preheating that remains Repone K mother liquor I described in step 7), tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling), the circular flow of material be Repone K slurry in crystallizer 1 times of volume/hour, until the Repone K slurry I of gained contains the potassium chloride that accounts for Repone K slurry I gross weight 4.9%;

5), Repone K slurry I is transported to DTB type II effect flash evaporation crystallizer by slurries formula forced circulation pump and carries out flash concentration cooling; In II effect flash evaporation crystallizer, temperature of charge is controlled at 48-52 ℃, vacuum degree control adopts vapor pressure 1.0Mpa steam-jet compression pump at-0.094Mpa～-0.096Mpa(while vacuumizing, the mixing steam producing is as the preheating that remains Repone K mother liquor I described in step 7), tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling), the circular flow of material be Repone K slurry in crystallizer 1 times of volume/hour, until the Repone K slurry II of gained contains the potassium chloride that accounts for Repone K slurry II gross weight 11.0%.

6), Repone K slurry II is transported to DTB type III effect flash evaporation crystallizer by slurries formula forced circulation pump and carries out flash distillation decrease temperature crystalline, in III effect flash evaporation crystallizer, temperature of charge is controlled at 18-22 ℃, vacuum degree control adopts vapor pressure 1.0Mpa steam-jet compression pump at-0.098Mpa～-0.099Mpa(while vacuumizing, tail gas is taken away by water cycle vacuum pump after vertical pipe type condenser is cooling), the circular flow of material be Repone K slurry in crystallizer 1 times of volume/hour, until the Repone K slurry III of gained contains the potassium chloride that accounts for Repone K slurry III gross weight 16.4%.

7), Repone K slurry III is by centrifugation (centrifugal rotational speed is 1200 revs/min, and the time is 10 minutes), obtains the Repone K wet product that 3160 kilograms of water content are 3%, temperature is the Repone K mother liquor I 11m altogether of 20 ℃ ³, the secondary steam that Repone K mother liquor I utilizes II effect flash evaporation crystallizer and I effect flash evaporation crystallizer to produce successively carries out preheating, and temperature rises to 50 ℃ by 20 ℃, returns to step (1) and dissolves raw material Repone K.

8) the Repone K wet product that is, 3% by 2820 kilograms of water content of centrifugal gained is by vibra fluidized bed drying (temperature during vibra fluidized bed drying is 125 ℃), cross 40 eye mesh screens, obtain 2735 kilograms of food-grade potassium chloride finished products, KCE content is 99.2%, sodium chloride content is 0.78%, and calcium magnesium is all less than 0.0001%, and heavy metal and arsenic are all less than 1ppm, water content is 0.1%, and median size is 0.4mm.

In the present embodiment, dissolve insulating process and consume altogether 920 kilograms of steam, 2170 kilograms of flash cooling crystallisation process consumption steam, 940 kilograms of drying process consumption steam, folding steam mono-consumption is 1473 kgs/tonne of Repone K.

Embodiment 4: a kind of method that multistage flash evaporation cooling continuous crystallisation is produced food-grade potassium chloride, carry out successively following steps:

1) Repone K that is, 96.5% by 3120 kilograms of content drops into the 10.5m through preheating (temperature is 50-52 ℃) ³repone K mother liquor I and 1m ³in tap water, be mixed with Repone K supersaturated solution, be heated to 110 ℃ (under agitation in chuck, passing into steam), after potassium chloride dissolves, obtain saturated potassium chloride solution I, in the saturated potassium chloride solution I of gained, contain altogether the Repone K of 6030kg;

2), in above-mentioned whole saturated potassium chloride solution I, first add potassium hydroxide, until regulate the pH value of saturated potassium chloride solution I to reach 12, then add 3.1 kilograms of stirring and dissolving of calcium oxide, add respectively again 3.7 kilograms of ammonium chlorides and 9.4 kilograms of potassium primary phosphates, after stirring 30min, at 100-110 ℃ of temperature, be incubated sedimentation, the insulation settling time is 2 hours; Saturated potassium chloride solution I, by being incubated after sedimentation, obtains supernatant liquor;

3), by step 2) supernatant liquor of gained is 5 microns by aperture the cartridge filter with heat-insulating property filters, the saturated potassium chloride solution (filtering the filtrate of gained) of removing after insoluble substance is neutralized to neutrality with hydrochloric acid, (suspended substance is less than 0.5mg/l to obtain saturated potassium chloride solution II, potassium chloride concentration is 36.5%, Ca2+:0.0024%, Mg2+:0.0012%, Fe≤0.0001%, heavy metal≤0.00005%).

4), step 4)～8) with embodiment 2.

Final 2776 kilograms of food-grade potassium chloride finished products, KCE content is 99.5%, sodium chloride content is 0.43%, calcium 0.0012%, magnesium 0.0008%, heavy metal and arsenic are all less than 1ppm, and water content is 0.12%, and median size is 0.7mm.

In the present embodiment, dissolve insulating process and consume altogether 1010 kilograms of steam, 2180 kilograms of flash cooling crystallisation process consumption steam, 990 kilograms of drying process consumption steam, folding steam mono-consumption is 1506 kgs/tonne of Repone K.

The method that embodiment 5, a kind of multistage flash evaporation cooling continuous crystallisation are produced food-grade potassium chloride, carry out successively following steps:

1) Repone K that is, 96.5% by 3120 kilograms of content drops into the 10.5m through preheating (temperature is 50-52 ℃) ³repone K mother liquor I and 1m ³in tap water, be mixed with Repone K supersaturated solution, be heated to 110 ℃ (under agitation in chuck, passing into steam), after potassium chloride dissolves, obtain saturated potassium chloride solution I, in the saturated potassium chloride solution I of gained, contain altogether the Repone K of 6030kg;

2), in above-mentioned whole saturated potassium chloride solution I, first add potassium hydroxide, until regulate the pH value of saturated potassium chloride solution I to reach 12, then add 3.1 kilograms of stirring and dissolving of calcium oxide, add respectively again 7.5 kilograms of ammonium chlorides and 22.5 kilograms of potassium primary phosphates, after stirring 30min, at 100-110 ℃ of temperature, be incubated sedimentation, the insulation settling time is 2 hours; Saturated potassium chloride solution I, by being incubated after sedimentation, obtains supernatant liquor;

3), by step 2) supernatant liquor of gained is 5 microns by aperture the cartridge filter with heat-insulating property filters, the saturated potassium chloride solution (filtering the filtrate of gained) of removing after insoluble substance is neutralized to neutrality with hydrochloric acid, (suspended substance is less than 0.5mg/l to obtain saturated potassium chloride solution II, potassium chloride concentration is 36.5%, Ca2+:0.00003%, Mg2+:0.00008%, Fe≤0.00005%, heavy metal≤0.00005%).

4), step 4)～8) with embodiment 2.

Final 2760 kilograms of food-grade potassium chloride finished products, KCE content is 99.5%, sodium chloride content is 0.40%, calcium 0.00006%, magnesium 0.0002%, heavy metal and arsenic are all less than 1ppm, and water content is 0.11%, and median size is 0.7mm.

In the present embodiment, dissolve insulating process and consume altogether 990 kilograms of steam, 2200 kilograms of flash cooling crystallisation process consumption steam, 990 kilograms of drying process consumption steam, folding steam mono-consumption is 1514 kgs/tonne of Repone K.

For technical superiority of the present invention is better described, with reference to existing production technique and patent of invention, carried out following comparative example:

Comparative example 1,

According to the disclosed a kind of production process of refined potassium chloride of Chinese invention patent " production process of refined potassium chloride " (201010533173.1) of the Liu Li equality application of Tianjin Changlu Hangu Saltern Co., Ltd, the Repone K that is 96.5% by content is made saturated potassium chloride solution, to adding 1560 kilograms, 96.5% Repone K in 6m3 saturated potassium chloride solution, form supersaturation Klorvess Liquid I again; This supersaturation Klorvess Liquid I is filtered through 20 order strainers, squeeze in heating kettle, be heated to 105 ℃, by Repone K, all dissolving is complete, then filters with 400 object stainless steel hot-water filters, obtains the refining saturated solution II of Repone K.The refining saturated solution II of Repone K is cooled to 30 ℃ through vacuum cooling crystallizer, and crystallisation by cooling obtains refined potassium chloride slurry.Refined potassium chloride slurry, through centrifuge dewatering, obtains the refined potassium chloride wet product that 1260 kilograms of water content are 3.5%, then after warm air drying, obtains 1218 kilograms of refined potassium chloride products.KCE content is 98.8%, and sodium chloride content is 0.98%, calcium 0.092%, and magnesium 0.048%, heavy metal is less than 20ppm, and arsenic is less than 4ppm, and water content is 0.1%, and median size is 0.4mm.In this comparative example, dissolve insulating process and consume altogether 2080 kilograms of steam, 440 kilograms of drying process consumption steam, folding steam mono-consumption is 2069 kgs/tonne of Repone K.This comparative example is compared with respect to the present invention, and the shortcoming of its existence is that steam mono-consumption is high, and product granularity is little, and the foreign matter content such as calcium magnesium is high.

Comparative example 2,

According to the method that in the Chinese invention patent of the applications such as the Zhang Peilin of Haijing Group Co., Ltd., Changlu, Tianjin City " by the method for dual circulation method production edible potassium chloride " (201110146158.6), disclosed a kind of dual circulation method is produced edible potassium chloride, the Repone K that is 96.5% by content carries out high-temperature digestion in dissolver, Repone K solubility after dissolving is 35.9-36.4 degree Beaume, and temperature is 105 ℃; Klorvess Liquid after high-temperature digestion is filtered, and filtering accuracy is 5 microns; Klorvess Liquid after filtering is pumped into one section of vaporizer and carry out one section of evaporation, the temperature of Klorvess Liquid is 92-97 ℃, and concentration is 35.9-36.4 degree Beaume, and the vacuum tightness in vaporizer is 78-83Kp; Klorvess Liquid through one section of evaporation is pumped into flash evaporator and carry out dual circulation, vacuum tightness is 90-95Kp, uses steam heating flash evaporator, makes temperature rise to 35-40 ℃; One section of feed liquid obtaining with dual circulation is pumped into whizzer and dewater, the potassium chloride after dehydration is dried under 125 ℃ of conditions.In gained Potassium Chloride Product, KCE content is 98.6%, and sodium chloride content is 1.18%, calcium 0.086%, and magnesium 0.042%, heavy metal is less than 20ppm, and arsenic is less than 4ppm, and water content is 0.1%, and median size is 0.3mm.It is 3228 kgs/tonne of Repone K that this comparative example rolls over steam mono-consumption, and quality product and steam mono-consumption are all poor than method of the present invention.

Comparative example 3,

According to high Song credit, wait the production technique of disclosed a kind of high-purity potassium chloride in the Chinese invention patent " a kind of production technique of high-purity potassium chloride " (200510124224.4) of applying for, the Repone K that the purity of take is 96.5% is raw material, by the Repone K saturated solution I that obtains soluble in water; Saturated potassium chloride solution I, by filtering, is removed to the saturated clear liquid II that insolubles obtains Repone K; The saturated clear liquid II of Repone K, by evaporation concentration, until there is crystal to separate out, is made Repone K supersaturated solution III; Supersaturated solution III, through filtering and impurity removing, makes the Repone K supersaturated solution IV without solid insoluble; Repone K supersaturated solution IV is cooled to-6 ℃～-6.5 ℃ crystallizations, obtain crystalline potassium chloride and mother liquor mixture, through centrifugation, obtain potassium chloride and mother liquor V, wet product potassium chloride is finished product after drying, KCE content is 98.7%, sodium chloride content is 1.08%, calcium 0.088%, magnesium 0.047%, heavy metal is less than 20ppm, arsenic is less than 4ppm, and water content is 0.1%, and median size is 0.4mm.In this comparative example, folding steam mono-consumption is 2748 kgs/tonne of Repone K, and because the temperature of crystallisation by cooling need to be reduced to-6 ℃～-6.5 ℃, so current consumption is large.

Comparative example 4,

According to the rear people method of disclosed narration in the Chinese invention patent of wishing the applications such as Guilin " a kind of energy-saving technique of producing the fertile potassium of edible chlorine " (201110070362.4) of Kechuang foodstuff additive company limited of Lianyun Harbour, the Repone K that is 96.5% by content is dissolved in the water, add cleaner to carry out removal of impurities, after filtration, obtain saturated Repone K clear liquid.Repone K clear liquid carries out preheating with being pumped into preheater I, through preheater I, carry out preheating post chlorization potassium clear liquid temperature and reach 80 ℃, converge with the mother liquor of draft tube baffle crystallizer overflow and the Repone K clear liquid after preheater preheating, through forced circulation pump, deliver into heating fumigators 2, through heating fumigators heating absorption heat, be warmed up to after 108 ℃, then enter draft tube baffle crystallizer 3 intercrystallines.Utilize the conveying of magma pump, magma is sent to whizzer and carries out separation, obtain potassium chloride wet product, after dry, obtain Repone K finished product, wherein KCE content is 99.0%, and sodium chloride content is 0.88%, calcium magnesium is all less than 0.0001%, heavy metal and arsenic are all less than 1ppm, and water content is 0.1%, and median size is 0.5mm.Because this comparative example's Repone K is to dissolve at normal temperatures, therefore need a large amount of evaporation moisture content crystallization to go out Repone K, although adopted mechanical vapour compressor, by the temperature producing in evaporative process, be that 90 ℃ of secondary steams recompress, temperature is brought up to 110 ℃, can reduce the unit consumption of steam, but amount to steam mono-consumption, still reach 2514 kgs/tonne of Repone K, and the unit consumption of electricity is more taller than the present invention.

Comparative example 5,

According to < < application multiple-effect flash evaporation recrystallize method, produce the method for informing of purified salt > >, the Repone K that is 96.5% by content is soluble in water, after the pre-treatment such as dissolution filter, obtain hot clear saturated saturated potassium chloride solution.The clear saturated saturated potassium chloride solution of heat is by being pumped in the circulation tube of I effect flash evaporation crystallizer, be mixed into flash chamber with circulation Repone K mother liquor, by flash evaporation, separate out Repone K crystallization, and sink in the salt leg of base of evaporator, after bittern countercurrent washing, be regularly discharged in salt slurry tank.Mother liquor is inhaled into recycle pump, the flash evaporation of proceeding to circulate after mixing with the clear saturated bittern of the heat adding operation.Mother liquor after the evaporation of I effect is entered in II effect by weir tank, and I effect double evaporation-cooling vapour removes warm Brine pre-heater direct heating bittern, in like manner, carries out the cyclical operation of II effect flash evaporation.Mother liquor after the evaporation of II effect is entered in III effect by weir tank, and II effect secondary steam removes low temperature Brine pre-heater direct heating bittern, in like manner, carries out the cyclical operation of III effect flash evaporation.Finally, the mother liquor after the evaporation of III effect is entered in mother liquor tank by weir tank, as next circulating mother liquor, uses.III effect secondary steam removes vapour liquid separator, then through water spray and steam, with water coolant, makes vapor condensation, and the water coolant of heat goes water cooling tower to recycle, and non-condensable gas is got rid of by steam and formed condition of high vacuum degree.The salt slurry of discharging from three flash evaporation advections is mixture salt slurry tank, with being pumped into thickener, in this solid phase sedimentation thickening.The Repone K circulating mother liquor of discharging from III effect is discharged a system part with 10% ratio with pump, and another part goes strainer to purify, and the clear saturated saturated potassium chloride solution that then returns to I effect flash evaporation crystallizer and heat mixes evaporation.Through KCE content centrifugal, that obtain after drying, be 99.1%, sodium chloride content is 0.86%, calcium 0.083%, and magnesium 0.056%, heavy metal is less than 20ppm, and arsenic is less than 4ppm, and water content is 0.1%, and median size is 0.3mm.In this comparative example, folding steam mono-consumption is 1849 kgs/tonne of Repone K, and quality product is poorer than the present invention, the present invention is high for energy loss-rate, and in gained evaporation condensed water, contain a small amount of Repone K, and can only be as potassium chloride dissolving use, unnecessary part is discharged as waste water.

Finally, it is also to be noted that, what more than enumerate is only several specific embodiments of the present invention.Obviously, the invention is not restricted to above embodiment, can also have many distortion.All distortion that those of ordinary skill in the art can directly derive or associate from content disclosed by the invention, all should think protection scope of the present invention.

Claims (8)

1. the method that multistage flash evaporation cooling continuous crystallisation is produced food-grade potassium chloride, is characterized in that in turn including the following steps:

1), by weight content for >=96% Repone K drops in solution and is heated to 100～110 ℃, obtain 100～110 ℃ of saturated potassium chloride solution I at temperature;

Described solution is the Repone K mother liquor I after the preheating of tap water or following step 7) gained;

2), in saturated potassium chloride solution I, add successively alkali and cleaner, be incubated sedimentation, the insulation settling time is 1～3 hour; The add-on of described alkali is for regulating pH to 12 ± 0.2 of saturated potassium chloride solution I;

Described cleaner is comprised of calcium oxide, ammonium chloride and composition A; Described composition A is at least one in phosphoric acid, potassium primary phosphate and Secondary ammonium phosphate;

The addition of described calcium oxide is 0.04～0.12% of Repone K quality in saturated potassium chloride solution I;

The addition of described ammonium chloride is 0.06%～0.24% of Repone K quality in saturated potassium chloride solution I;

The addition of described composition A is 0.16%～0.72% of Repone K quality in saturated potassium chloride solution I;

3), at 100～110 ℃, by step 2) supernatant liquor of gained is incubated filtration by cartridge filter, and the filtrate of filtering gained is neutralized to neutrality with hydrochloric acid, obtains saturated potassium chloride solution II;

4), by pump delivery to I effect flash evaporation crystallizer, to carry out flash distillation cooling concentrated for saturated potassium chloride solution II; Processing parameter is as follows:

Temperature is controlled at 76～80 ℃, and vacuum degree control is at-0.080Mpa～-0.086Mpa, circular flow be I effect flash evaporation crystallizer material amount 0.5～1 volume doubly/hour;

Until the Repone K slurry I of gained contains the potassium chloride that accounts for Repone K slurry I gross weight 3.5～5%;

5), Repone K slurry I is transported to II effect flash evaporation crystallizer by forced circulation pump to carry out flash distillation cooling concentrated, processing parameter is as follows:

Temperature is controlled at 48～52 ℃, and vacuum degree control is at-0.094Mpa～-0.096Mpa, circular flow be II effect flash evaporation crystallizer material amount 0.5～-1 volume doubly/hour;

Until the Repone K slurry II of gained contains the potassium chloride that accounts for Repone K slurry II gross weight 9.5～11%;

6), Repone K slurry II is transported to III effect flash evaporation crystallizer by another forced circulation pump to carry out flash distillation cooling concentrated, processing parameter is as follows:

Temperature is controlled at 18～22 ℃, and vacuum degree control is at-0.098Mpa～-0.099Mpa, circular flow be III effect flash evaporation crystallizer material amount 0.5～1 volume doubly/hour;

Until the Repone K slurry III of gained contains the potassium chloride that accounts for Repone K slurry III gross weight 15～16.5%;

7), Repone K slurry III carries out separation by whizzer, obtains Repone K wet product and Repone K mother liquor I;

Repone K mother liquor I is moved out of food-grade potassium chloride production line with 5～10% volume ratios;

The secondary steam that remaining Repone K mother liquor I utilizes II effect flash evaporation crystallizer and I effect flash evaporation crystallizer to produce successively carries out preheating, thereby return to step 1), as solution, uses;

8), Repone K wet product dry after packing, obtain food-grade potassium chloride.

2. the method that multistage flash evaporation cooling continuous crystallisation according to claim 1 is produced food-grade potassium chloride, is characterized in that:

When Repone K mother liquor I after the preheating of step 7) gained is in shortage as the solution in step 1), with tap water, supply.

3. the method that multistage flash evaporation cooling continuous crystallisation according to claim 1 and 2 is produced food-grade potassium chloride, is characterized in that:

Described step 2) alkali is potassium hydroxide;

Cartridge filter in described step 3) is the cartridge filter with heat-insulating property, and material is titanium material, and aperture is 5 microns.

4. the method that multistage flash evaporation cooling continuous crystallisation according to claim 3 is produced food-grade potassium chloride, is characterized in that:

Described I effect flash evaporation crystallizer, II effect flash evaporation crystallizer, III effect flash evaporation crystallizer are DTB type crystallizer.

5. the method that multistage flash evaporation cooling continuous crystallisation according to claim 4 is produced food-grade potassium chloride, is characterized in that:

On the vapour liquid separator top duct of described I effect flash evaporation crystallizer, II effect flash evaporation crystallizer and III effect flash evaporation crystallizer, install ammonium chloride evaporation gas washing apparatus additional, guarantee not contain in secondary steam Repone K.

6. the method that multistage flash evaporation cooling continuous crystallisation according to claim 5 is produced food-grade potassium chloride, is characterized in that:

Vapor pressure 0.9～1.1Mpa that the steam-jet compression pump of the III effect flash evaporation crystallizer using in the II effect flash evaporation crystallizer using in the I effect flash evaporation crystallizer using in described step 4), step 5), step 6) is selected.

7. the method that multistage flash evaporation cooling continuous crystallisation according to claim 6 is produced food-grade potassium chloride, is characterized in that:

Being dried of described step 8), adopts vibrated fluidized bed to carry out.

8. the method that multistage flash evaporation cooling continuous crystallisation according to claim 7 is produced food-grade potassium chloride, is characterized in that:

In described step 7):

The secondary steam that remaining ammonium chloride mother liquor I utilizes II effect flash evaporation crystallizer and I effect flash evaporation crystallizer to produce successively carries out preheating, temperature by 20 ℃ rise to >=50 ℃.