CN105084367B - The method that current potential dispersion microwave acid wash removes polysilicon lines cutting waste material impurity - Google Patents
The method that current potential dispersion microwave acid wash removes polysilicon lines cutting waste material impurity Download PDFInfo
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- CN105084367B CN105084367B CN201510509392.9A CN201510509392A CN105084367B CN 105084367 B CN105084367 B CN 105084367B CN 201510509392 A CN201510509392 A CN 201510509392A CN 105084367 B CN105084367 B CN 105084367B
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Abstract
The method that a kind of present invention current potential dispersion microwave acid wash removes polysilicon lines cutting waste material impurity, the method utilizes after under alkalescence condition disperseing the silicon in polysilicon lines cutting waste material and silicon-carbide particle, then removes boron impurities therein, phosphorus and ferrum with the method for microwave reinforced pickling.Step is：First cutting waste material is carried out pretreatment, remove polyglycol solution, after drying, obtain silicon and carborundum mixed-powder；Add and adjust pH value to 12～14 with certain density weak caustic solution, stir rearmounted enter ultrasound wave in, make granule fully dispersed, neutralization solution is to after neutral, then carries out microwave reinforced acid cleaning process.The technological process of the present invention is simple, and technological parameter is stable, and the surface potential changing granule with weak caustic solution regulation pH can be fully dispersed.Weak caustic solution can be effectively reduced discharge with Reusability.Carried out with microwave field can significantly strengthening pickling reaction, the pickling reaction response time substantially shortens, and dust removal rate significantly improves.
Description
Technical field
Invention is related to purifying polycrystalline silicon wire cutting waste recovery technology, in particular by weak base reagent current potential dispersion-microwave
The method that pickling removes the impurity such as boron, phosphorus in this waste material.
Background technology
At present, produce the monocrystal silicon of solaode and polysilicon chip mainly adopts multi-wire saw to process, in the course of processing
In, substantial amounts of cutting waste material slurry can be produced, in addition to the Polyethylene Glycol as abrasive suspension agent, solid break flour is mainly carborundum
（70%）, silicon（25%）With impurity such as Fe.According to existing research work, Polyethylene Glycol can be reclaimed by methods such as centrifugations
It is recycled for use as suspending agent, and is left pressed powder waste material, then great majority are used for extracting carborundum therein.And for therein
Silica flour material, then do not apply outlet well.In view of the high-purity source formation of itself and quite big in cutting process
Part（At least 30%）Break flour shape is cut into by mill, if relatively inexpensive efficient technology can be adopted to be enriched with further, separate,
It is purified to the purity of solar-grade polysilicon, to make solar energy polycrystalline silicon battery material such that it is able to recycling, then not
Achieve resource only for expensive polycrystalline silicon raw material cutting waste material to reclaim, and for current solar energy polycrystal silion cell
The reduction of cost also has very important realistic meaning.The silicon of these chip waste materials, the purity of itself has reached the sun
Can more than 5N required by battery, other impurities such as carborundum, metal fillings etc. it should be all the mode of physical mixed therewith, because
This is theoretically should be able to be allowed to realize enrichment, purification, reached by the enforcement of simple, cheap multiple technologies means
Purity to solar energy level silicon.
From polycrystalline silicon cut waste, be purified to the purity grade of solar energy level silicon, it will face two the heaviest
The difficult problem wanted or challenge.One be fine SiC powder in cutting waste material powder efficient removal, especially granularity and silica flour think
The removing of most sic powder.Otherwise silicon-carbide particle will may carry in follow-up high temperature
The pure stage is difficult to cost-effective removing, thus significantly impacting the photoelectric conversion efficiency of polysilicon.Another is difficult
Topic is then boron in cutting waste material, the deep removal problem of phosphorus impurities.Remove boron, phosphorus in view of pyrometallurgical method to reaching from silicon
Target degree technically almost cannot, therefore we must the incident stage will the boron in cutting waste material powder,
Phosphorus is removed to Passing Criteria.Otherwise all will have no chance being capable of economical and efficient ground production department high-purity solar energy polycrystal for full process stream journey
Silicon.Around this two crucial problem, we have carried out distinctive research and development.In our disclosed patents
（201210162413.0）The inside it is proposed that using wet separation ultrafine SiC powders therein effective ways, for passing through
Simple wet process realize the preliminary concentration sample of chip powder Silicon-rich powder in addition it is also necessary to impurity therein for example ferrum, copper,
Boron, phosphorus etc. carry out removing process, and pickling is conventional method, but disclose the result reported from present, generally existing acid
Wash the difficult problem that efficiency is low, depth pickling removes difficult to reach polysilicon requirement.Around the solution of this problem, in this patent to mesh
Front commonly used wet process acid dissolving removes a kind of more fruitful pickling impurity-removing method of the open process of soluble impurity.
There is the method for removing various metal impurities in chip powder for some technology at present, had the side of conventional pickling
Method, such as article（Tzu-Hsuan Tsai）Middle disclosure, at normal temperatures and pressures, the HNO of waste material and 1M concentration3Stirring reaction 40
Minute, the content of Fe can drop to 0.57%.With above impurity-removing method, removal effect is notable, but is as prolonging of response time
Long, removal efficiency declines, and the restriction that final removal degree is still difficult to meet impurity content requires.
Content of the invention
In order to solve the above problems, it is an object of the invention to provide a kind of technological process is simple, technological parameter is stable, remove impurity
Efficiency significantly improves, and effectively reduces discharge, can remove polysilicon lines cutting with the current potential dispersion-microwave acid wash of reduces cost again
The method of waste material impurity.
The technical scheme is that：Current potential dispersion-microwave acid wash removes polysilicon lines cutting waste material impurity
Method, the method center line cutting waste material uses surface potential regulation and control-centrifuging to process first, obtains Si content and exceedes
The content of more than 80% silica flour, wherein Fe is the content of 5.56%, Cu is 0.31%.Fig. 1 is the electromicroscopic photograph of this silica flour.Silica flour
Particle diameter be about 0.8 μm, and have agglomeration, metal impurities should be attached on Si granule or be entrained in reuniting
Among.According to solid-liquid phase reaction principle of dynamics, when acid solution is only and metal impurities are fully contacted, react the ratio that just can carry out
More thoroughly.So, adjust pH to more than 12 with the ammonia spirit containing ammonium salt organic acid first in the present invention, then use ultrasound wave
Process silica flour so as to can be fully dispersed, allow metal impurities fully to come out.Due to microwave, to have body heat temperature raising fast and strong
The feature of the micro stirring divergent function on big molecular scale, can be effectively facilitated the contact with acid solution for the metal impurities and
Reaction, so carrying out pickling impurity removal in microwave field, not only can shorten the response time, impurity-eliminating effect also can be fairly obvious.
Specifically include following steps：
Step 1. is divided in advance：
Take a certain amount of polysilicon lines cutting waste material powder having removed the Organic substances such as Polyethylene Glycol, according to liquid-solid ratio 3～
6:After 1wt adds deionized water, stir 30～60 minutes, the ammonia spirit of the organic acid ammonium salt being 8-15% with concentration adjusts silica flour
The pH value of solution, to 12-14, after stirring, is put into dispersion in ultrasound wave, after 30～60 minutes, is obtained silica flour solution, standby；
Step 2. neutralizes：
Mixed solution after step 1 is processed is 3000-5000 rev/min in centrifugal rotational speed, centrifugation time is 15
～25 minutes, after centrifugation, supernatant can recycle, and after the silica flour of lower floor takes out, adds a small amount of deionized water to stir
Mix uniformly, and the salt acid for adjusting pH being 3mol/l with concentration, to neutral, obtains suspension, standby；
Step 3. microwave pickling：
The inorganic acid solution adding a certain amount of concentration to be 2mol/l-5mol/L in the suspension that step 2 is obtained, puts into
In microwave chemical reactor, it is 500-1000w in microwave power, reaction was taken out after 5～20 minutes, standby；
Step 4. filtering drying：
By the suspension after step 3 is processed, filter, be washed with deionized 3～5 post-dryings, obtain is high-purity
What silica flour, the boron in described high-purity silicon powder and the content of phosphorus all can reach in solar-grade polysilicon the two impurity content will
Ask.
Further, described organic acid ammonium salt saline solution is ammonium citrate, ammonium oxalate, ammonium tartrate or malic acid ammonium.
Further, described inorganic acid solution is hydrochloric acid, nitric acid, sulphuric acid or citric acid.
Further, in described silica flour, the clearance of ferrum can reach more than 90%, and the content of boron and phosphorus is respectively less than 0.1ppm.
The principle of the present invention is：The method passes through acid cleaning process, in pretreatment stage, with ammonia adjust pH value to 12 with
On, now granule electrostatic repulsion each other is larger, can be effective against the reunion of granule, and helps with ultrasonic Treatment,
More sufficiently disperse after enabling granule, so that being swept along boron in silica flour microgranule group, the impurity such as phosphorus to come out.In addition,
Fully strengthen pickling course of reaction using microwave, make to be agglomerated body of powder due to the effect of microwave, in polar molecule strenuous exercise
Auxiliary stirring under, wrapped impurity can fully be released, and so that acid molecule is fully spread, penetrate into powder
In aggregate, realize sufficiently contacting between nonmetallic chip microparticle and acid molecule and reacting, thus by nonmetallic chip
Granule is abundant, be completely converted into the nonmetallic ion form being dissolved in aqueous solution, thus by simple
Filter, pickling, washing remove it is possible to fast and efficiently wash nonmetallic inclusion.
The present invention, compared with existing report or disclosed technology, has advantageous effect in that：
（1）The technological process of the present invention is simple, and technological parameter is stable, adjusts, with weak caustic solution, the surface that pH changes granule
Current potential can be fully dispersed, than the good impurity removing effect of direct pickling.
（2）Weak caustic solution both can effectively reduce discharge with Reusability, again can be with reduces cost.
（3）Carried out with microwave field can significantly strengthening pickling reaction, the pickling reaction response time will than traditional stirring and pickling
Substantially shorten, dust removal rate significantly improves.
Brief description
Fig. 1 is the electromicroscopic photograph of silica flour used by the present invention.
Fig. 2 is the impurity technological principle that current potential dispersion-microwave acid wash removes in monocrystal silicon and polysilicon lines cutting waste material
Flow chart.
Specific embodiment
Following examples are intended merely to preferably illustrate and illustrate the technical scheme that above content of the invention is covered, and not only
It is limited only within the actual conditions cited by embodiment and process parameters range.
Embodiment 1：
By the mixed-powder of silicon and carborundum according to liquid-solid ratio 4:After 1 adds deionized water, stir 40 minutes.With concentration it is
The ammonia of 8% ammonium citrate adjusts the pH value of this silica flour solution to 12, after stirring, puts in ultrasound wave and disperses, 30 minutes
Put in centrifuge tube after taking-up and be centrifuged, centrifuge speed is 4500 revs/min, centrifugation time is 15 minutes.Centrifugation
Separate
Afterwards, supernatant can recycle, and after the silica flour of lower floor takes out, add a small amount of deionized water stirring, be used in combination
The salt acid for adjusting pH of 3mol/L is to neutrality.
Add the hydrochloric acid solution of 3mol/L in this silica flour suspension, put in microwave chemical reactor, microwave power is
500W, reaction was taken out after 10 minutes.Solution after overpickling, filters, is washed with deionized 5 post-dryings, obtain remove impurity
Silica flour afterwards, the clearance of its ferrum can reach 95%, and the content of boron and phosphorus is respectively less than 0.1ppm.
Embodiment 2：
By the mixed-powder of silicon and carborundum according to liquid-solid ratio 5:After 1 adds deionized water, stir 40 minutes.With concentration it is
The ammonia spirit of 15% ammonium tartrate adjusts the pH value of this silica flour solution to 12.5, after stirring, puts in ultrasound wave and divides
Dissipate, put in centrifuge tube after taking out within 40 minutes and be centrifuged, centrifuge speed is 4000 revs/min, centrifugation time is 18
Minute.After centrifugation, supernatant can recycle, and after the silica flour of lower floor takes out, adds a small amount of deionized water stirring, and
Salt acid for adjusting pH with 3mol/L is extremely neutral.
Add the sulfuric acid solution of 3mol/L in this silica flour suspension, put in microwave chemical reactor, microwave power is
1000W, reaction was taken out after 8 minutes.Solution after overpickling, filters, is washed with deionized 5 post-dryings, obtain remove impurity
Silica flour afterwards, the clearance of its ferrum can reach 93%, and the content of boron and phosphorus is respectively less than 0.1ppm.
Embodiment 3：
By the mixed-powder of silicon and carborundum according to liquid-solid ratio 6:After 1 adds deionized water, stir 50 minutes.With concentration it is
The ammonia spirit of 15% malic acid ammonium adjusts the pH value of this silica flour solution to 13, after stirring, puts into dispersion in ultrasound wave,
Put in centrifuge tube after taking out within 45 minutes and be centrifuged, centrifuge speed is 3500 revs/min, centrifugation time is 20 points
Clock.From
After the heart separates, supernatant can recycle, and after the silica flour of lower floor takes out, adds a small amount of deionized water stirring,
And the salt acid for adjusting pH with 3mol/L is extremely neutral.
Add the sulfuric acid solution of 3mol/L in this silica flour suspension, put in microwave chemical reactor, microwave power is
800W, reaction was taken out after 12 minutes.Solution after overpickling, filters, is washed with deionized 5 post-dryings, obtain remove impurity
Silica flour afterwards, the clearance of its ferrum can reach 92%, and the content of boron and phosphorus is respectively less than 0.1ppm.
Embodiment 4：
By the mixed-powder of silicon and carborundum according to liquid-solid ratio 3:After 1 adds deionized water, stir 60 minutes.With concentration it is
The ammonia spirit of 10% ammonium oxalate adjusts the pH value of this silica flour solution to 13.5, after stirring, puts into dispersion in ultrasound wave,
Put in centrifuge tube after taking out within 50 minutes and be centrifuged, centrifuge speed is 4000 revs/min, centrifugation time is 20 points
Clock.After centrifugation, supernatant can recycle, and after the silica flour of lower floor takes out, add a small amount of deionized water stirring, be used in combination
The salt acid for adjusting pH of 3mol/L is to neutrality.
Add the salpeter solution of 3mol/L in this silica flour suspension, put in microwave chemical reactor, microwave power is
900W, reaction was taken out after 10 minutes.Solution after overpickling, filters, is washed with deionized 5 post-dryings, obtain remove impurity
Silica flour afterwards, the clearance of its ferrum can reach 92%, and the content of boron and phosphorus is respectively less than 0.1ppm.
Embodiment 5：
By the mixed-powder of silicon and carborundum according to liquid-solid ratio 5:After 1 adds deionized water, stir 30 minutes.With concentration it is
The ammonia spirit of 10% ammonium citrate adjusts the pH value of this silica flour solution to 14, after stirring, puts into dispersion in ultrasound wave,
Put in centrifuge tube after taking out within 60 minutes and be centrifuged, centrifuge speed is 4000 revs/min, centrifugation time is 20 points
Clock.From
After the heart separates, supernatant can recycle, and after the silica flour of lower floor takes out, adds a small amount of deionized water stirring,
And the salt acid for adjusting pH with 3mol/L is extremely neutral.
Add the hydrochloric acid solution of 3mol/L in this silica flour suspension, put in microwave chemical reactor, microwave power is
700W, reaction was taken out after 18 minutes.Solution after overpickling, filters, is washed with deionized 5 post-dryings, obtain remove impurity
Silica flour afterwards, the clearance of its ferrum can reach 93%, and the content of boron and phosphorus is respectively less than 0.1ppm.
Claims (3)
1. current potential dispersion-microwave acid wash removes the method for polysilicon lines cutting waste material impurity it is characterised in that the method is concrete
Comprise the following steps：
Step 1. is divided in advance：
Take a certain amount of polysilicon lines cutting waste material powder having removed Polyethylene Glycol, according to liquid-solid ratio 3～6:1wt add go from
After sub- water, stir 30～60 minutes, the ammonia spirit of the organic acid ammonium salt being 8-15% with concentration adjust the pH value of silica flour solution to
12-14, after stirring, puts into dispersion in ultrasound wave, after 30～60 minutes, obtains silica flour solution, standby；
Step 2. neutralizes：
Silica flour solution after step 1 is processed is 4000-6000 rev/min in centrifugal rotational speed, centrifugation time is 15～25
Minute, after centrifugation, supernatant can recycle, and after the silica flour of lower floor takes out, adds a small amount of deionized water stirring all
Even, and the salt acid for adjusting pH being 3mol/L with concentration, to neutral, obtains silica flour suspension, standby；
Step 3. microwave pickling：
The inorganic acid solution adding a certain amount of concentration to be 2mol/L-5mol/L in the silica flour suspension that step 2 is obtained, puts into
In microwave chemical reactor, reaction under microwave power is for 500-1000w was taken out after 5～20 minutes, standby；
Step 4. filtering drying：
By the solution after step 3 is processed, filter, be washed with deionized 3～5 post-dryings, the silicon of 4-6N must be reached
Powder, the boron in silica flour and the content of phosphorus all can reach the content requirement of the two impurity in solar-grade polysilicon.
2. method according to claim 1 is it is characterised in that described ammonium salt organic acid is ammonium citrate, ammonium oxalate, winestone
Sour ammonium or malic acid ammonium.
3. method according to claim 1 is it is characterised in that described inorganic acid solution is hydrochloric acid, nitric acid, sulphuric acid or Fructus Citri Limoniae
Acid.
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