CN1843900A - Method for preparing electronic grade phosphoric acid by fusion crystallization method - Google Patents
Method for preparing electronic grade phosphoric acid by fusion crystallization method Download PDFInfo
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Abstract
The invention relates to a process for preparaing electronic phosphoric acid with melt crystallization method. It comprises following steps: removing arsenic from industrial phosphoric acid; heating crystal tube to minus two Deg. C to ten Deg. C; putting phosphoric acid of 21-28 Deg. C into crystal tube for circultion, the crystal layer growing to 2-4 cm; stewing crystal tube for 15-25 minutes and keeping the temperature, then heating crystal tube at speed of 2-5 Deg. C per hour, stopping when quality of melted crystal is 10-40% of thant of initial one; cleaning crystal layer with cleaning liquid with its tempeature near at temperature of fusible point of phosphoric acid hemi-crystalline. The certificated electronic phosphoric acid can be got after crystallization and perspiration; and electronic phosphoric acid of high purity reaching to FCC4 standard can be got after cleaning. The invention is characterized by high removal rate for foreign matter, low energy consumtion, wide range for treating raw material with different purity, high purity of geot product and sound economic benefit.
Description
Technical field
The present invention relates to the crystallization technique field, particularly fusion-crystallization method purified industrial level phosphoric acid is produced the method for electron-level phosphoric acid.
Technical background
Commercially available phosphoric acid mainly contains two kinds of production methods at present, and a kind of is to make with mineral acid (mainly being sulfuric acid) and Rock Phosphate (72Min BPL) acidification reaction, is referred to as the phosphoric acid by wet process process.Another kind is with charcoal Rock Phosphate (72Min BPL) reduction to be become elemental phosphorously in electric furnace, and elemental phosphorous being reoxidised into behind the Vanadium Pentoxide in FLAKES and water prepared in reaction phosphoric acid is referred to as the dry method process phosphoric acid.
The phosphoric acid that can be used for electronic semi-conductor's industry generally is dry method phosphoric acid, because by contrast, dry method phosphoric acid product purity is higher than phosphoric acid by wet process, just can reach the requirement of electron-level phosphoric acid through simple relatively scavenging process.In actual applications and since insoluble solid particle or metal ion all may be between fine circuits the conducting electric current, make it short circuit.So electron-level phosphoric acid all has harsh requirement to insoluble solid particle and most metal ion content.Wherein in the U.S. FCC4 industry standard, require various impurity ion content all to be lower than 1ppm to the high purity electron-level phosphoric acid.
Consider the running cost factor, the raw material acid that is used to prepare electron-level phosphoric acid generally need reach more than the national PHOSPHORIC ACID TECH.GRADE standard.The purified method mainly contains extraction process, ion exchange method, crystallization process etc. at present.Compare with other several method, the simple energy consumption of crystallization process equipment is low, and operating process is polluted little, the product purity height that obtains, and colourity is good.So since the eighties, it is quite active to utilize the crystallization technique effect to carry out the research of wet phosphoric acid refining, main technological route has following four kinds: (i) go out H by crystallization in the phosphoric acid by wet process
3PO
41/2H
2O, 29.32 ℃ of fusing points; Or H3PO4,42.35 ℃ of fusing points; Phosphoric acid and additive such as formation complex salt crystals such as urea, melamine are separated out; (iii) crystallization precipitation of phosphorus hydrochlorate is converted into phosphoric acid then; (II) solvent precipitation, this method adopts the solvent that dissolves each other fully with water, as methyl alcohol, ethanol, Virahol or propyl alcohol etc., makes phosphoric acid and water-soluble in solvent, and impurity formation insoluble salt precipitation is removed.
More than research mainly concentrates on purification of wet process phosphoric acid for preparing and is equipped with on technical grade and the following rank phosphoric acid thereof, and the report that reaches the electronic-grade requirement with crystallization process is less relatively, rarely seen three examples:
Russian patent 2209178 usefulness crystallization processs purify thermal phosphoric acid, and product reaches the CooTB Ty of Russia electronic industry phosphoric acid standard, but its products obtained therefrom purity does not reach the standard of FCC4 high-purity phosphoric acid; Japanese Patent 3193614,3237009 and 2000026111 respectively with solution crystal process and the fusion-crystallization method electron-level phosphoric acid of further purifying, obtain foreign matter content at other high-purity phosphoric acid of ppb level, but this method is higher to the raw material acid purity requirement, requires it to reach the electron-level phosphoric acid rank.
Summary of the invention:
The present invention prepares electron-level phosphoric acid with fusion-crystallization method purified industrial level phosphoric acid.The present invention is less demanding with raw material phosphoric acid, and the hot method or the phosphoric acid by wet process after the purification that reach national technical grade standard can obtain the high purity electron-level phosphoric acid by technology of the present invention.
The method of fusion-crystallization legal system power backup sub level phosphoric acid of the present invention may further comprise the steps:
(1) is-10 ~-15 ℃ crystallizer with phosphoric acid by condensate temperature, emits phosphoric acid, reduce condensate temperature, at this moment form one deck phosphoric acid crystal film on the crystallizer to-45 ~-35 ℃;
(2) crystallizer is warming up to-2 ~ 10 ℃, logical 21 ~ 28 ℃ phosphoric acid is gone into the crystallizer circulation, the flow velocity of phosphoric acid is 600 ~ 800ml/min, allow crystal layer slowly grow 2 ~ 3.5 hours, grow behind the fine and close crystal layer again cooling rate with 2 ~ 4 ℃/h and allow crystal layer regrowth 1.5 ~ 2.5 hours, raw material phosphoric acid is discharged crystallizer;
(3) keep the temperature of crystallizer to leave standstill 15 ~ 25 minutes, the raw material phosphoric acid of crystal layer surface attachment is dripped as far as possible, the temperature rise rate with 2 ~ 5 ℃/h raises the temperature of crystallizer then, and fusing crystal layer quality is that 10 of original crystal layer quality ~ 40% o'clock stops;
(4) clean crystal layer with near the scavenging solution acid of temperature phosphoric acid half crystalline fusing point.Clean-out system is for last time testing products obtained therefrom or product dilution back solution.
The content of arsenic is higher in the PHOSPHORIC ACID TECH.GRADE, and the directly requirement that reaches electron-level phosphoric acid by crystallization process difficulty relatively, so phosphoric acid will have an arsenic removal step before crystallization, specific as follows:
Phosphoric acid is put into there-necked flask, in the time of 50 ~ 70 ℃, feed hydrogen sulfide, behind reaction 50 ~ 60min, the emptying of blowing air bubbling there is not the hydrogen sulfide of reaction, add the diatomite that accounts for total phosphoric acid quality 5 ~ 10%, suction filtration drips hydrogen peroxide until clarification again in phosphoric acid, remove the solid granule that suspends in the phosphoric acid.
Below concrete steps of the present invention are further explained:
The crystallization processes of separating out the phosphoric acid half crystalline from raw material phosphoric acid comprises, crystallization, sweating, four steps of cleaning.Be specially:
Step (1) is the biofilm stage, at first the crystallizer condensate temperature is dropped to about-10 ~-15 ℃, logical phosphoric acid slowly circulates crystallizer once, after phosphoric acid is emitted, viscosity is big at low temperatures owing to phosphoric acid, can overwork one deck phosphoric acid liquid film on the crystallization tube wall, reduces temperature then to-45 ~-35 ℃, make this liquid membrane crystal, at this moment form one deck phosphoric acid crystal film on the crystallizer.
Step (2) is a crystallisation stage, crystallizer is warming up to-2 ~ 10 ℃, and logical phosphoric acid is gone into the crystallizer circulation, and the flow velocity of phosphoric acid is 600 ~ 800ml/min, allow slowly growth 2 ~ 3.5 hours of crystal layer, grow behind the fine and close crystal layer again cooling rate with 2 ~ 4 ℃/h and allow crystal layer regrowth 1.5 ~ 2.5 hours.Raw material phosphoric acid is discharged crystallizer, prepare to carry out the sweating operation.
Step (3) is the sweating stage, keep the temperature of crystallizer to leave standstill 15 ~ 25 minutes, the raw material phosphoric acid of crystal layer surface attachment is dripped as far as possible, temperature rise rate with 2 ~ 5 ℃/h raises the temperature of crystallizer then, melt a part of crystal, the impurity in the crystal layer is removed, reach the purpose of purification, when fusing crystal layer quality is 20 ~ 35% left and right sides of original crystal layer quality, stop sweating.
Step (4) is a wash phase, after the sweat emptying, cleans crystal layer with the acid of last time testing after products obtained therefrom or product dilute, and the temperature of scavenging solution should be also near phosphoric acid half crystalline fusing point.
The used crystallizer of the present invention is two layers of columnar hollow structure of hard glass system, the internal circulation refrigerant, the temperature of tube-surface can be adjusted to fixed overcooling temperature, outer loop raw material phosphoric acid.
The thickness of crystal layer is decided on the size of crystallizer and the efficient of sweating operation, the too thin meeting of crystal layer causes product yield low, crystal layer is too thick, in the affected process of sweating, the impurity that is mingled with in the crystal layer can not or through discharging crystal layer for a long time, can strengthen the operating time, dust removal rate is reduced, general crystal layer thickness 2 ~ 4cm is advisable.
So-called sweating is that round-robin phosphoric acid in crystallizer is discharged, and after reaching mother liquor and separating, impurity inside and outside the crystal is removed in this crystal layer sweating, thereby phosphoric acid is further purified.When the quality of separating out the phosphoric acid semihydrate crystal was used recently representing of the phosphoric acid liquid scale of construction of dripping, the fusing weight range of operating phosphoric acid about sweating was 10 ~ 40 weight %, preferably operates in the scope of 20 ~ 35 weight %.According to present inventors' research, the fusing amount below 10 weight % in, thereby because the insufficient very difficult acquisition high-purity phosphoric acid of sweating effect, the situation that surpasses 40 weight %, because most of impurity is removed, it continues sweating, do not reach the purpose of removal of impurities, also made yield reduce.
According to this phosphoric acid crystalline sweating operation, though can obtain highly purified phosphoric acid, also can before or after sweating, clean the phosphoric acid semihydrate crystal of separating out if necessary at the partial crystallization tube-surface with phosphoric acid of the present invention or with the mixed diluted acid of pure water, further purify.
This displacement is cleaned and to be meant on phosphoric acid semihydrate crystal crystal layer surface, with contacting than mixture arbitrarily of distilled water and high-purity phosphoric acid, removes the operation attached to the raw material phosphoric acid of phosphoric acid semihydrate crystal.Because this operation can will be removed effectively attached to the impurity on crystal layer surface.
Obtain highly purified phosphoric acid crystallization by the present invention, in case of necessity this crystallization is dissolved in the ultrapure water, the high-purity phosphoric acid solution that obtains thus can reach the standard of electronic-grade.
Effect of the present invention is to reach the hot method of national technical grade standard or the phosphoric acid by wet process process crystallization after the purification and after the sweating stage, can obtain qualified electron-level phosphoric acid product; Through reaching the high purity electron-level phosphoric acid product of FCC4 standard behind crystallization, sweating and the wash phase.This method is applicable to the thermal phosphoric acid that meets purity requirement or the purification of the PHOSPHORIC ACID TECH.GRADE behind the wet phosphoric acid refining, also can be used for the further purification of qualified electron-level phosphoric acid.With existing fusion-crystallization prepare electron-level phosphoric acid technology for example JP3237009 compare with JP2000026111, foreign ion clearance height of the present invention, production energy consumption is low, and the product rank that obtains is wide, purity is high, and manageable raw material acid purity range is wide, has considerable economic.
Embodiment:
Embodiment 1
500g puts into there-necked flask with raw material phosphoric acid (forming as shown in table 1), goes into bubbling in the phosphoric acid at the logical hydrogen sulfide of 50 ~ 70 ℃ of temperature ranges, behind the reaction 50min, blowing air bubbling 30min puts into 5g diatomite, suction filtration, drip several hydrogen peroxide and go into phosphoric acid, until clarification.The content of arsenic and sulphur sees Table 2 in the phosphoric acid of processing back.
Table 1 streams is formed (%) ppm
The streams component | Hot legal system PHOSPHORIC ACID TECH.GRADE I | Wet purification preparing industrial grade phosphoric acid II |
P 2O 5 | 62.0 | 62.0 |
SO 4 2- | 20 | 10 |
Na | 10.5 | 130 |
Fe | 20 | 21 |
As | 44.5 | 25.3 |
Pd | 10 | 12 |
The variation ppm of phosphoric acid arsenic content after the logical hydrogen sulfide treatment of table 2
The raw material acid foreign matter content | Hot legal system PHOSPHORIC ACID TECH.GRADE I | Wet purification preparing industrial grade phosphoric acid II |
As | 21.4 | 10.0 |
SO 4 2- | 24.1 | 13.3 |
Embodiment 2,3,4:
Raw material phosphoric acid (hot legal system PHOSPHORIC ACID TECH.GRADE I and wet purification preparing industrial grade phosphoric acid II with deciding concentration, form and see Table 1) put into 500g at the hard glass container made, and control its temperature with thermostatic bath, come recycle feed phosphoric acid with peristaltic pump, use external diameter 2cm, two layers of round shape partial crystallization pipe of long 20cm are implemented by following operation and condition.Promptly in raw material phosphoric acid, soak crystallizer, decide the refrigerant (mixed solution of water and glycol or industrial spirit) of overcooling temperature, separate out the phosphoric acid semihydrate crystal on the heat-transfer surface surface of crystallizer at immersion pipe internal circulation.The concrete operations condition is listed in the table 1.
Table 3 crystallization condition
The embodiment experiment condition | 2 | 3 | 4 |
Initial condensation liquid temp ℃ | -10 | -15 | -10 |
Biofilm service temperature ℃ | -35 | -35 | -45 |
Phosphoric acid temperature ℃ | 25 | 28 | 21 |
Tc ℃ | 10 | 6 | -2 |
Phosphoric acid circular flow ml/min | 800 | 600 | 700 |
Crystal layer growth is to fine and close time min | 120 | 120 | 180 |
Temperature fall time min | 120 | 150 | 90 |
Cooling rate ℃/h | 2 | 3 | 4 |
Phosphoric acid crystallization content g | 124 | 102 | 115 |
Crystal layer thickness cm | 4 | 2.6 | 3.4 |
Through after the above operation, take out crystallizer, allow the phosphoric acid attached to the crystal layer surface drip.Sampling is analyzed, and each foreign matter content (ppm) is as table 4
Foreign matter content in table 4 crystal layer
Embodiment | 2 | 3 | 4 | |||
I | II | I | II | I | II | |
Fe | 2.1 | 1.9 | 3.0 | 2.5 | 3.8 | 3.5 |
As | 11.0 | 2.9 | 12.1 | 3.3 | 13.2 | 3.8 |
Na | 3.1 | 12.3 | 5.5 | 15.6 | 7.5 | 18.4 |
S | 2.1 | 1.3 | 3.1 | 2.2 | 5.3 | 3.3 |
Pb | 2.3 | 2.5 | 2.6 | 2.6 | 3.8 | 3.2 |
After obtaining crystal layer by above-mentioned condition attached to crystallizer, raw material phosphoric acid is emitted from crystallizer, after leaving standstill for some time, improve the temperature of cooling fluid, a part of crystal is melted, under the crystal layer surface current, quality every phosphoric acid is melted in for some time weighing when reaching 30% ~ 40% left and right sides of former crystal layer quality, stops the sweating operation, take out crystallizer, sampling analysis.The concrete operations condition sees Table 5, and (ppm) is as shown in table 6 for each foreign matter content.
Table 5 sweating operation
The embodiment experiment condition | 2 | 3 | 4 |
Heat-up rate ℃/h | 2 | 2 | 5 |
Fusing crystal layer quality % | 35 | 22 | 20 |
The content of impurity in the crystal layer after table 6 sweating
Embodiment | 2 | 3 | 4 | |||
I | II | I | II | I | II | |
Fe | 0.5 | 0.5 | 0.6 | 0.6 | 1.7 | 2.0 |
As | 1.7 | 0.9 | 1.7 | 1.0 | 1.9 | 1.1 |
Na | 1.5 | 6.2 | 2.3 | 6.5 | 3.9 | 7.6 |
S | 1.2 | 0.6 | 1.6 | 0.6 | 1.8 | 0.7 |
Pb | 1.0 | 1.1 | 1.1 | 1.1 | 1.3 | 1.2 |
Embodiment 5,6,7
Obtain the phosphoric acid crystal layer after the sweating among the embodiment 2,3,4, phosphoric acid that obtains with the present invention or phosphoric acid and pure water blended diluted acid clean the crystal layer surface, after the cleaning, crystal layer is all melted, and sampling analysis, the product foreign matter content is as shown in table 6.
Table 7 cleans the content of rear impurity
Embodiment | 5 | 6 | 7 | |||
I | II | I | II | I | II | |
Fe | 0.3 | 0.3 | 0.4 | 0.3 | 0.7 | 0.9 |
As | 0.7 | 0.6 | 0.8 | 0.7 | 0.8 | 0.7 |
Na | 1.0 | 3.7 | 1.8 | 3.9 | 2.7 | 4.1 |
S | 0.9 | 0.4 | 1.0 | 0.4 | 1.0 | 0.4 |
Pb | 0.7 | 0.8 | 0.9 | 0.8 | 0.6 | 0.9 |
All foreign matter contents of the present invention are all used inductive coupling plasma emission spectrograph VISTA-MPX analyzing and testing.
The present invention open and the preparation method and the product that propose, those skilled in the art can be by using for reference this paper content, and links such as appropriate change raw material, processing parameter realize.Method of the present invention and product are described by preferred embodiment, person skilled obviously can be in not breaking away from content of the present invention, spirit and scope to method as herein described with product is changed or suitably change and combination, realize the technology of the present invention.Special needs to be pointed out is, the replacement that all are similar and change apparent to those skilled in the artly, they are regarded as being included in spirit of the present invention, scope and the content.
Claims (6)
1. the method for a fusion-crystallization legal system power backup sub level phosphoric acid may further comprise the steps:
(1) is-10 ~-15 ℃ crystallizer with phosphoric acid by condensate temperature, emits phosphoric acid, reduce condensate temperature, at this moment form one deck phosphoric acid crystal film on the crystallizer to-45 ~ 35 ℃;
(2) crystallizer is warming up to-2 ~ 10 ℃, logical 21 ~ 28 ℃ phosphoric acid is gone into the crystallizer circulation, the flow velocity of phosphoric acid is 600 ~ 800ml/min, allow crystal layer slowly grow 2 ~ 3.5 hours, grow behind the fine and close crystal layer again cooling rate with 2 ~ 4 ℃/h and allow crystal layer regrowth 1.5 ~ 2.5 hours, raw material phosphoric acid is discharged crystallizer;
(3) keep the temperature of crystallizer to leave standstill 15 ~ 25 minutes, the raw material phosphoric acid of crystal layer surface attachment is dripped as far as possible, the temperature rise rate with 2 ~ 5 ℃/h raises the temperature of crystallizer then, and fusing crystal layer quality is that 10 of original crystal layer quality ~ 40% o'clock stops;
(4) clean crystal layer with near the scavenging solution acid of temperature phosphoric acid half crystalline fusing point.Clean-out system is for last time testing products obtained therefrom or product dilution back solution.
2. the method for fusion-crystallization legal system power backup sub level phosphoric acid as claimed in claim 1, it is characterized in that in the described method, clean the phosphoric acid semihydrate crystal of separating out the front or rear of step (4) with electron-level phosphoric acid or with the mixed diluted acid of pure water, further purify at the partial crystallization tube-surface.
3. the method for fusion-crystallization legal system power backup sub level phosphoric acid as claimed in claim 1 or 2, it is characterized in that described phosphoric acid carries out the arsenic removal step earlier: in the time of 50 ~ 70 ℃, feed hydrogen sulfide, behind reaction 50 ~ 60min, the emptying of blowing air bubbling there is not the hydrogen sulfide of reaction, the diatomite that adds total phosphoric acid quality 5 ~ 10%, suction filtration drips hydrogen peroxide until clarification again in phosphoric acid, remove the solid granule that suspends in the phosphoric acid.
4. the method for fusion-crystallization legal system power backup sub level phosphoric acid as claimed in claim 1, it is characterized in that described crystallizer is two layers of columnar hollow structure of hard glass system, internal circulation refrigerant, the temperature of tube-surface can be adjusted to fixed overcooling temperature, outer loop raw material phosphoric acid.
5. the method for fusion-crystallization legal system power backup sub level phosphoric acid as claimed in claim 1 is characterized in that the preferred 2 ~ 4cm of thickness of described crystal layer.
6. the method for fusion-crystallization legal system power backup sub level phosphoric acid as claimed in claim 1 is characterized in that described fusing crystal layer quality is 20 ~ 35% of original crystal layer quality.
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CN102020255A (en) * | 2010-04-29 | 2011-04-20 | 杨志勇 | Semi-continuous and multi-variety high-purity electronic grade phosphoric acid production process and equipment |
CN101774555B (en) * | 2010-02-02 | 2011-08-31 | 天津大学 | Method for preparing electronic grade phosphoric acid through liquid membrane crystallization |
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CN102515125A (en) * | 2011-12-31 | 2012-06-27 | 云南省化工研究院 | Arsenic-removing filtering method for high-concentration polyphosphoric acid |
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CN102583283A (en) * | 2012-01-13 | 2012-07-18 | 四川大学 | Method for preparing electronic-grade phosphoric acid via melting-crystallization |
CN103754844A (en) * | 2013-12-30 | 2014-04-30 | 广西明利化工有限公司 | Device for producing electrode-grade phosphoric acid by stirring crystallization |
CN103771374A (en) * | 2013-12-30 | 2014-05-07 | 广西明利化工有限公司 | Electronic grade phosphoric acid clapboard crystallizing device |
CN104030261A (en) * | 2013-12-30 | 2014-09-10 | 广西明利化工有限公司 | A production method of high-purity electronic grade phosphoric acid |
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