CN102659112A - Method for recovering silicon powder from monocrystalline and polycrystalline silicon cutting wastes by utilizing potential adjustment centrifugal process - Google Patents
Method for recovering silicon powder from monocrystalline and polycrystalline silicon cutting wastes by utilizing potential adjustment centrifugal process Download PDFInfo
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- CN102659112A CN102659112A CN2012101611126A CN201210161112A CN102659112A CN 102659112 A CN102659112 A CN 102659112A CN 2012101611126 A CN2012101611126 A CN 2012101611126A CN 201210161112 A CN201210161112 A CN 201210161112A CN 102659112 A CN102659112 A CN 102659112A
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Abstract
The invention discloses a method for recovering a silicon powder from monocrystalline and polycrystalline silicon cutting wastes by utilizing a potential adjustment centrifugal process. The method comprises the following steps of: firstly, performing pretreatment on the cutting wastes to remove a polyethylene glycol solution; drying to obtain a mixed powder of silicon and silicon carbide; adding water to the mixed powder and stirring; regulating a pH value to 6-9 by acid and base; performing centrifugal separation for a plurality of times, and then, adding the acid to an isolated upper layer suspension to regulate the pH value to 1-3 so as to enable a silicon powder aggregate to grow up; and performing standing settling for 30min or centrifugal settling for 5min to collect the silicon powder, wherein the purity of the silicon powder can reach more than 80 percent.
Description
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Technical field
The present invention relates to the recovery method of silica flour in silicon single crystal and the polysilicon lines cutting waste material.
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Background technology
The sun power utilization has become the important directions of new energy development; The research and development of various solar photocells are just among mushroom development; Wherein have the solar cell more than 80% all to adopt high purity polycrystalline silicon to make as basic material, in present all kinds of sensitive cell products in occupation of absolute dominant position.Usually, when the manufacturing solar cells silicon chip, earlier will be with section again behind the high-purity crystal silicon ingot casting.In the slice processing process; Account for the part of silicon ingot weight more than 30% and can be mixed formation heavy-gravity slug with the scrap metal that cuts abrasive material silicon carbide powder, grinding generation and as the polyoxyethylene glycol that the cutting abrasive suspension uses by the multi-thread Si powder waste material that cuts into fine sizes.In this slug; Being worth the highest composition is silicon; If be about 150,000 yuans in present solar-grade polysilicon per ton market average price, the silicon in the Separation and Recovery slug is processed into solar silicon wafers again, both can improve resource utilization; Reduce environmental hazard, can reduce the solar energy polycrystalline silicon production cost of cells again.
Produce at present silicon chip and mainly adopt the multifibres line cutting technology, the slug staple (massfraction) of generation has: the HIGH-PURITY SILICON about 20%, about 40% silit, about 30% polyoxyethylene glycol and water, about 5% metallic impurity such as iron.Silica flour in the cutting waste material of monocrystalline and polysilicon is originally as high-purity crystalline silicon, and foreign matter content is few, and it is high to recycle value.
At present the patented technology of report mainly is the recovery to silit and polyoxyethylene glycol in the cutting slug, less about the HIGH-PURITY SILICON recovery.The technology of Chinese patent 200710018636. 9 is earlier slug to be removed suspension agent and sticker; Again the solid that obtains is obtained the mixed powder of Si and SiC through flotation; Carry out gravity or centrifugal settling separation with the heavy-fluid of density between Si and SiC then, obtain purer SiC and Si micro mist through iron removal by magnetic separation at last.The technology of Chinese patent 200610029378. X is that monocrystalline silicon cutting waste liquor is handled with Hydrogen chloride, and mixes into runny compound; Again solid-liquid separation is carried out in compound heating, water and polyoxyethylene glycol steam together, condensation, dehydration, reclaim polyoxyethylene glycol, the solid that separation obtains is the mixture of silit and silicon; Water cleans this mixture twice then, handles dissolving silicon wherein with the mix acid liquor that nitric acid and hydrofluoric acid are formed, and final the recovery obtains silit.
The technical characterstic of various Separation and Recovery silicon more than the comprehensive evaluation can be known the general long and complicated operation of technical process, some method even silicon changed into compound by simple substance, further principle difficulty more also again.In addition, separation method has all been used some poisonous, that pollution is arranged reagent mostly.Though silicon is the integral part that recovery value is arranged in silicon single crystal and the polysilicon lines cutting slug most, does not also have a kind of simple sophisticated stripping technique can realize that its industriallization reprocessing cycle becomes high purity polycrystalline silicon, creates solar-grade polysilicon more at present.
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Summary of the invention
Key issue to be solved by this invention is to adopt the fine silica flour in surface potential regulation and control-centrifuging enriching and recovering silicon single crystal and the polysilicon lines cutting waste material.
Can know that in the online cutting slug, the median size of silicon is about 1 μ m after the sample test of fetching from domestic a plurality of producers, the median size of silit is about 10 μ m, differ about ten times, and the density of silicon is 2.4g/cm
3, the density of silit is 3.2g/cm
3About, therefore, the granularity of the two, volume and mass discrepancy are quite big.By means of the above difference of two kinds of particulates, the present invention proposes the method for two kinds of particulates of high efficiency separation.Consider in the surface potential-pH relation, when pH 6～9 the time, the surface potential of silicon is bigger; This moment, the mutual electrostatic repulsion effect between the silicon grain was bigger, silicon powder is disperseed in the aqueous solution fully and suspends, not free settling; And under same pH value of solution condition,, also be beneficial to the dispersion and the suspension of silicon-carbide particles though the silicon-carbide particles surface potential is bigger; But because himself granularity and quality are bigger; With making it overcome self electrostatic repulsion and settlement separate trend is bigger, thereby in the identical solution surface current potential field and the centrifugation field of force, the big multipotency of silicon powder wherein is in suspended state; Granularity silicon-carbide particle bigger than normal then can rapid precipitation at bottom, thereby realize and the separating of silicon.
In like manner; To the Si-rich phase micro mist that obtains after centrifugal, consider its surface potential-pH relationship characteristic, pH is 1～3 o'clock; The surface potential of silicon particle approaches zero; Promptly this moment, the mutual electrostatic repulsion between the silicon particle was minimum, and then silicon particle can be reunited rapidly with growing up and quicken and is deposited to container bottom, thereby with its quick recovery.
Technical scheme of the present invention is:
The method of electric potential regulating-spinning silicon chip line cutting waste material is following:
(1) cutting waste material pre-treatment
In silicon single crystal and polysilicon lines cutting waste material, add entry, liquid-solid ratio is 3:1.Add small amount of acid (available hydrochloric acid, nitric acid, sulfuric acid and Hydrocerol A, oxalic acid etc.) while stirring to remove other impurity elements such as polyoxyethylene glycol and iron, stir (this process can be carried out at normal temperatures) after 3～4 hours, filter, filter cake is dried.
Filter cake after the oven dry was put into grinding in ball grinder 10～30 minutes, obtained silicon and silit mixed powder.
(2) surface potential in the adjustment mixed powder aqueous suspension
Powder after grinding is put into container, add a certain amount of water, liquid-solid ratio is 3:1, adds alkali (available hydrogen sodium oxide, Pottasium Hydroxide, volatile salt, bicarbonate of ammonia, ammoniacal liquor etc.) then and regulates pH value to 6～9.The surface potential of silicon is much larger than silit at this moment, and interparticle mutual electrostatic repulsion effect maximum can make the tiny silicon powder particle of granularity keep suspended state in centrifugal process in solution.
(3) centrifugal separation processes
The slurry of the good specific pH value of above-mentioned adjusted is put into whizzer; Centrifugal rotational speed is 2500～5000 rev/mins; Centrifugation time is 10～30 minutes, and centrifugal number of times is 3～5 times, obtains stratified sample up and down and the settling of upper strata Si-rich phase suspension and lower floor richness silit is taken out respectively.
Seabed sediment can return step (1) circulation to carry out.
(4) adjustment Si-rich phase surface potential
The upper strata suspension-s that obtains after centrifugal is Si-rich phase; Add diluted acid (available Hydrogen chloride, rare nitric acid, acetic acid etc.) and regulate pH value to 1～3; Mutual electrostatic repulsion effect between this moment silicon particle is less, can be agglomerated into larger particles rapidly between particle and rapid subsidence obtains silica flour behind the filtering drying.
The beneficial effect that the present invention is compared with prior art had is:
(1) technical process of the present invention is simple, and processing parameter is stable, separates with whizzer, and the lock out operation time is short, and it is low to consume energy.
(2) the present invention realizes separating according to granularity (volume, the quality) difference of silicon and silit; And it is different by different pH value lower surface current potentials; Silica flour is fully suspended and be difficult for sedimentation in centrifuge field; But the silicon-carbide particle that granularity is bigger can rely on self bigger weight sinking, thereby obtains the higher carborundum powder of purity from the sedimentator bottom, from suspension-s, collects tiny Si-rich phase particulate.
(3) the used main separating medium of the present invention is a water, and the chemical reagent of micro mist surface potential all is common common acid or alkali in the used adjusting aqueous solution, belongs to nontoxic reagent; Therefore pollute little; And after centrifugal, water can recycle, and realizes zero release basically.
(4) technical process that relates among the present invention all can be carried out at normal temperatures.
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Description of drawings
Fig. 1 is the silica flour basic flowsheet of coal preparation in surface potential regulation and control-centrifuging Separation and Recovery silicon single crystal and the polysilicon cutting waste material.
Fig. 2 is the silica flour XRD figure that utilizes surface potential regulation and control-centrifuging to obtain.
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Embodiment
Specific embodiment 1:
Is that 4:1 adds entry with the mixed powder of getting rid of polyoxyethylene glycol according to liquid-solid ratio, and using sodium hydroxide solution to regulate the pH value is 7, and mixing solutions is put into whizzer; Centrifugation time is 10 minutes; 5000 rev/mins of rotating speeds, centrifugal number of times are 3 times, and taking out upper strata liquid and regulating the pH value is 2; The rapid sedimentation of silica flour, oven dry is reclaimed; Subnatant returns in the former mixed powder solution.From XRD figure, can see in the silica flour of recovery and only contain small amount of carbonized silicon.
Specific embodiment 2:
Is that 10:1 adds entry with the mixed powder of getting rid of polyoxyethylene glycol according to liquid-solid ratio, and using sodium hydroxide solution to regulate the pH value is 8, and mixing solutions is put into whizzer, and centrifugation time is 20 minutes, and 3000 rev/mins of rotating speeds, centrifugal number of times are 5 times.Taking out upper strata liquid and regulating the pH value is 2, the rapid sedimentation of silica flour, and oven dry is reclaimed; Subnatant returns in the former mixed powder solution.Its XRD result is identical with embodiment one.
Specific embodiment 3:
Is that 5:1 adds entry with the mixed powder of getting rid of polyoxyethylene glycol according to liquid-solid ratio, and using sodium hydroxide solution to regulate the pH value is 9, and mixing solutions is put into whizzer, and centrifugation time is 15 minutes, and 4000 rev/mins of rotating speeds, centrifugal number of times are 4 times.Taking out upper strata liquid and regulating the pH value is 2, the rapid sedimentation of silica flour, and oven dry is reclaimed; Subnatant returns in the former mixed powder solution.Its XRD result is identical with embodiment one.
Specific embodiment 4:
Is that 8:1 adds entry with the mixed powder of getting rid of polyoxyethylene glycol according to liquid-solid ratio, and using sodium hydroxide solution to regulate the pH value is 8, and mixing solutions is put into whizzer, and centrifugation time is 10 minutes, and 4500 rev/mins of rotating speeds, centrifugal number of times are 5 times.Taking out upper strata liquid and regulating the pH value is 2, the rapid sedimentation of silica flour, and oven dry is reclaimed; Subnatant returns in the former mixed powder solution.Its XRD result is identical with embodiment one.
Specific embodiment 5:
Is that 3:1 adds entry with the mixed powder of getting rid of polyoxyethylene glycol according to liquid-solid ratio, and using sodium hydroxide solution to regulate the pH value is 9, and mixing solutions is put into whizzer, and centrifugation time is 20 minutes, and 4000 rev/mins of rotating speeds, centrifugal number of times are 4 times.Taking out upper strata liquid and regulating the pH value is 1.0, the rapid sedimentation of silica flour, and oven dry is reclaimed; Subnatant returns in the former mixed powder solution.Its XRD result is identical with embodiment one.
Specific embodiment 6:
Is that 3:1 adds entry with the mixed powder of getting rid of polyoxyethylene glycol according to liquid-solid ratio, and using sodium hydroxide solution to regulate the pH value is 6, and mixing solutions is put into whizzer, and centrifugation time is 25 minutes, and 3500 rev/mins of rotating speeds, centrifugal number of times are 4 times.Taking out upper strata liquid and regulating the pH value is 1.5, the rapid sedimentation of silica flour, and oven dry is reclaimed; Subnatant returns in the former mixed powder solution.Its XRD result is identical with embodiment one.
Claims (3)
1. the method for silica flour in electric potential regulating reclaiming by centrifuge monocrystalline and the polysilicon cutting waste material, its characteristic
Be that it may further comprise the steps:
The pre-treatment of cutting waste material
In silicon single crystal and polysilicon cutting waste material, add entry, and add small amount of acid, stir after 3～4 hours, filter the mixed powder of oven dry and grinding dispersed silicon and silit;
(2) surface potential of regulation and control mixed powder
The mixed powder of silicon and silit is added entry according to certain liquid-solid ratio 3～10:1, and adding acid or alkali, to regulate the pH value be 6～9, stirs;
(3) centrifugal separation processes
Behind the centrifugal several times of mixing liquid, obtain stratified sample up and down and the settling of upper strata Si-rich phase suspension and lower floor richness silit is taken out respectively;
(4) surface potential of adjustment Si-rich phase is with quick recovery silica flour
The upper strata suspension-s that obtains after centrifugal is Si-rich phase, adds rare acid for adjusting pH value to 1～3, and the silicon particle aggregation becomes larger particles and sedimentation rapidly, obtains silica flour behind the filtering drying.
2. according to the described method of claim 1, it is characterized in that: centrifugal number of times is 3～5 times in the said step (3), and the settling of the rich silit of lower floor returns to step (1) and recycles.
3. according to the described method of claim 1, it is characterized in that: all carry out at normal temperatures said step (1)-(4).
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103172066A (en) * | 2013-02-18 | 2013-06-26 | 江苏双净净化科技有限公司 | Rotational-flow purifying process for silicon carbide powder |
| CN105084367A (en) * | 2015-08-18 | 2015-11-25 | 北京科技大学 | Method for removing polysilicon wire cutting waste impurities by potential dispersion-microwave pickling process |
| CN105174266A (en) * | 2015-08-18 | 2015-12-23 | 北京科技大学 | Method for removing impurity iron in wire-electrode cutting waste materials of polycrystalline silicon and monocrystalline silicon |
| CN106957060A (en) * | 2016-01-12 | 2017-07-18 | 光宇材料股份有限公司 | The application method and the product by its acquisition of useless silicon mud |
| CN107758672A (en) * | 2017-12-04 | 2018-03-06 | 中国恩菲工程技术有限公司 | The recovery method of silica flour in crystalline silicon cutting waste material |
| US10343924B2 (en) | 2016-01-12 | 2019-07-09 | Get Green Energy Corp., Ltd. | Using method of waste silicon slurry and products obtained therefrom |
| CN112424401A (en) * | 2018-06-18 | 2021-02-26 | 道达尔欧洲公司 | Method for recovering submicron Si particles from Si wafer production process and silicon wafer production equipment |
| CN113019716A (en) * | 2021-03-04 | 2021-06-25 | 中国矿业大学 | Extraction method for multiple centrifugal separation of mixed abrasive dust of artificial joint |
| CN113860310A (en) * | 2021-09-27 | 2021-12-31 | 连云港市沃鑫高新材料有限公司 | Method for extracting nanoscale silicon carbide from superfine silicon carbide tailings |
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103172066A (en) * | 2013-02-18 | 2013-06-26 | 江苏双净净化科技有限公司 | Rotational-flow purifying process for silicon carbide powder |
| CN103172066B (en) * | 2013-02-18 | 2015-05-20 | 江苏双净净化科技有限公司 | Rotational-flow purifying process for silicon carbide powder |
| CN105084367A (en) * | 2015-08-18 | 2015-11-25 | 北京科技大学 | Method for removing polysilicon wire cutting waste impurities by potential dispersion-microwave pickling process |
| CN105174266A (en) * | 2015-08-18 | 2015-12-23 | 北京科技大学 | Method for removing impurity iron in wire-electrode cutting waste materials of polycrystalline silicon and monocrystalline silicon |
| CN105174266B (en) * | 2015-08-18 | 2018-06-29 | 北京科技大学 | The minimizing technology of impurity iron in a kind of polysilicon and monocrystalline silicon wire cutting waste material |
| CN106957060A (en) * | 2016-01-12 | 2017-07-18 | 光宇材料股份有限公司 | The application method and the product by its acquisition of useless silicon mud |
| US10343924B2 (en) | 2016-01-12 | 2019-07-09 | Get Green Energy Corp., Ltd. | Using method of waste silicon slurry and products obtained therefrom |
| CN107758672A (en) * | 2017-12-04 | 2018-03-06 | 中国恩菲工程技术有限公司 | The recovery method of silica flour in crystalline silicon cutting waste material |
| CN112424401A (en) * | 2018-06-18 | 2021-02-26 | 道达尔欧洲公司 | Method for recovering submicron Si particles from Si wafer production process and silicon wafer production equipment |
| CN113019716A (en) * | 2021-03-04 | 2021-06-25 | 中国矿业大学 | Extraction method for multiple centrifugal separation of mixed abrasive dust of artificial joint |
| CN113860310A (en) * | 2021-09-27 | 2021-12-31 | 连云港市沃鑫高新材料有限公司 | Method for extracting nanoscale silicon carbide from superfine silicon carbide tailings |
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Application publication date: 20120912 |