CN103395788B - Ingot-casting silicon powder with controllable grain size as well as preparation method and application thereof - Google Patents
Ingot-casting silicon powder with controllable grain size as well as preparation method and application thereof Download PDFInfo
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- CN103395788B CN103395788B CN201310316412.1A CN201310316412A CN103395788B CN 103395788 B CN103395788 B CN 103395788B CN 201310316412 A CN201310316412 A CN 201310316412A CN 103395788 B CN103395788 B CN 103395788B
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 78
- 238000005266 casting Methods 0.000 title claims abstract description 74
- 238000002360 preparation method Methods 0.000 title claims abstract description 30
- 239000011863 silicon-based powder Substances 0.000 title abstract description 19
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 69
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 59
- 239000010703 silicon Substances 0.000 claims abstract description 59
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 34
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 21
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 19
- 239000007788 liquid Substances 0.000 claims abstract description 14
- 238000000926 separation method Methods 0.000 claims abstract description 10
- 238000001035 drying Methods 0.000 claims abstract description 5
- 229910052755 nonmetal Inorganic materials 0.000 claims abstract description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 350
- 239000000377 silicon dioxide Substances 0.000 claims description 175
- 235000013312 flour Nutrition 0.000 claims description 173
- 238000000034 method Methods 0.000 claims description 45
- 230000008569 process Effects 0.000 claims description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 27
- 238000003756 stirring Methods 0.000 claims description 22
- 230000003647 oxidation Effects 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 16
- 239000002253 acid Substances 0.000 claims description 14
- 239000002184 metal Substances 0.000 claims description 14
- 229910052751 metal Inorganic materials 0.000 claims description 14
- 239000007787 solid Substances 0.000 claims description 12
- 239000007769 metal material Substances 0.000 claims description 10
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 8
- 238000004140 cleaning Methods 0.000 claims description 7
- 239000004744 fabric Substances 0.000 claims description 7
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 7
- 239000011707 mineral Substances 0.000 claims description 7
- 239000002210 silicon-based material Substances 0.000 claims description 7
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 6
- -1 polypropylene Polymers 0.000 claims description 6
- 239000004743 Polypropylene Substances 0.000 claims description 4
- 229920001155 polypropylene Polymers 0.000 claims description 4
- 239000004677 Nylon Substances 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 claims description 3
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 3
- 229920001778 nylon Polymers 0.000 claims description 3
- 229920000573 polyethylene Polymers 0.000 claims description 3
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 claims description 3
- 229920004933 Terylene® Polymers 0.000 claims description 2
- 239000008367 deionised water Substances 0.000 claims description 2
- 229910021641 deionized water Inorganic materials 0.000 claims description 2
- 238000010907 mechanical stirring Methods 0.000 claims description 2
- 239000005020 polyethylene terephthalate Substances 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 238000000227 grinding Methods 0.000 abstract description 14
- 238000005554 pickling Methods 0.000 abstract description 10
- 238000012216 screening Methods 0.000 abstract description 5
- 230000007935 neutral effect Effects 0.000 abstract description 4
- 239000002699 waste material Substances 0.000 abstract description 3
- 239000013078 crystal Substances 0.000 abstract description 2
- 150000007522 mineralic acids Chemical class 0.000 abstract 1
- 238000005406 washing Methods 0.000 abstract 1
- 239000012535 impurity Substances 0.000 description 22
- 230000000052 comparative effect Effects 0.000 description 17
- 238000005119 centrifugation Methods 0.000 description 12
- 238000001291 vacuum drying Methods 0.000 description 9
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 6
- 238000012797 qualification Methods 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000009826 distribution Methods 0.000 description 5
- 239000000155 melt Substances 0.000 description 5
- 238000010301 surface-oxidation reaction Methods 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 150000002739 metals Chemical class 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
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- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 230000003292 diminished effect Effects 0.000 description 2
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- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 2
- 239000011856 silicon-based particle Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 235000019628 coolness Nutrition 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
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- 230000001939 inductive effect Effects 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
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- 229920000728 polyester Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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Abstract
The invention provides a preparation method of ingot-casting silicon powder with controllable grain size. The preparation method comprises the following steps of: pickling silicon waste by using hydrofluoric acid and hydrochloric acid; pickling by using hydrochloric acid and nitric acid; pickling by using inorganic acid; carrying out solid-liquid separation and washing until the pH value is neutral, so as to obtain primary silicon powder; placing the primary silicon powder in a dryer with the temperature of 30-120 DEG C, setting the vacuum degree of the dryer as3.0*10<-2>-8.0*10<-2>MPa, and drying for 2-24 hours, so as to obtain the silicon powder with the grain size of 10 microns to 5 centimeters; grinding the obtained silicon powder, and screening by using a non-metal screen, so as to obtain the ingot-casting silicon powder with the grain size of 0.1-0.5mm. The preparation method can be used for solving a problem that the silicon powder is easy to melt during an ingot-casting process due to the low surface oxidization degree or extremely low grain size of the silicon powder. The invention further provides ingot-casting silicon powder with controllable grain size and application of the ingot-casting silicon powder in the field of solar poly-crystal silicon ingot preparation.
Description
Technical field
The present invention relates to solar grade polycrystalline silicon material field, be specifically related to controlled ingot casting silica flour of a kind of granularity and its preparation method and application.
Background technology
Along with clean energy is more and more taken seriously, solar cell is rapidly developed, the production also fast development of solar cell raw material polycrystal silicon ingot.The silicon chip that solar cell uses needs to carry out cutting processing to silicon ingot, and silicon ingot needs to be removed in defective to the head of silicon ingot, afterbody and some shades etc. region with diamond band saw blade before section, therefore in sawed-off process, a large amount of silica flours is just produced, silicone content in these silica flours is greater than 96%, granularity is mainly distributed between 8-12 μm, in addition, also be mixed with the diamond particles, dust pug, organic impurity etc. of some metallic impurity, trace, directly being discarded by these silica flours not only can welding, especially a kind of wasting of resources.
At present, although traditional purifying silicon powder method can obtain the silica flour of higher degree, silicon powder surface degree of oxidation is low, and the silica flour that this surface oxidation degree is low in solar energy polycrystalline silicon ingot casting process easily melts, and is unfavorable for the long brilliant of silicon ingot; In addition, silicon cutting waste material granularity is less, ingot casting poor effect; Therefore, be necessary a kind of method providing efficient recovery scrap silicon, the method needs to solve the problem that silicon powder surface degree of oxidation is low and silicon particle size is meticulous.
Summary of the invention
For overcoming the defect of above-mentioned prior art, the invention provides the preparation method of the controlled ingot casting silica flour of a kind of granularity, the method can not only remove the metallic impurity in scrap silicon effectively, further improve and reclaim the shortcoming that silicon powder surface degree of oxidation is low and granularity is meticulous, and then the problem that when solving the ingot casting caused because silicon powder surface degree of oxidation is low or granularity is meticulous, silica flour easily melts.In addition, present invention also offers the controlled ingot casting silica flour of a kind of granularity and the application in solar energy polycrystal silicon ingot preparation field thereof.
First aspect, the invention provides the preparation method of the controlled ingot casting silica flour of a kind of granularity, comprises the following steps:
S10, by scrap silicon dispersed with stirring in pure water, add hydrofluoric acid and hydrochloric acid, regulate solid-liquid weight ratio to be 1:1-1:20, stir after 10-120 minute, carry out solid-liquid separation, obtain elementary silica flour, wherein, described hydrofluoric acid and hydrochloric acid add total amount be the 0.1-2 of described useless silicon material quality doubly;
S20, in described elementary silica flour, add hydrochloric acid and nitric acid, after dispersed with stirring 0.5-2 hour, soak 0.5-10 hour, carry out solid-liquid separation subsequently, obtain solid, wherein, described hydrochloric acid and nitric acid add total amount be the 0.1-2 of described elementary silica flour quality doubly;
S30, by step S20 gained solid dispersal in pure water, add mineral acid, solid-liquid weight ratio is regulated to be 1:1-1:20, after dispersed with stirring 0.5-2 hour, solid-liquid separation, gained solid pure water cleans 2-3 time to pH neutrality, and wherein, the add-on of described mineral acid is 0.01-0.5 times of step S20 gained solid masses;
S40, step S30 gained solid is placed in Vacuumdrier, the vacuum tightness arranging drying machine is 3.0 × 10
-2-8.0 × 10
-2mPa, temperature is 30-120 DEG C, after dry 2-24 hour, obtains silica flour, and the size range of described silica flour is 10 μm of-5cm;
S50, step S40 gained silica flour is carried out break process, sieve with the screen cloth of 30-150 object non-metallic material subsequently, obtain the ingot casting silica flour that size range is 0.1mm-0.5mm, wherein, in the process of described break process, the parts directly contacted with described silica flour adopt rigid non-metallic material.
Preferably, described scrap silicon is the waste material produced in the process of band saw worked crystal silicon ingot.
Preferably, in described step S10, the volume ratio of described hydrofluoric acid and described hydrochloric acid is 1:2-10:1; In described step S20, the volume ratio of described hydrochloric acid and described nitric acid is 1:2-10:1.
Further preferably, in described step S10, the volume ratio of described hydrofluoric acid and described hydrochloric acid is 3:2; In described step S20, the volume ratio of described hydrochloric acid and described nitric acid is 5:1.
Preferably, the massfraction of described hydrofluoric acid is 49-50%, and the massfraction of described hydrochloric acid is 36-38%, and the massfraction of described nitric acid is 65-68%.
Further preferably, the massfraction of described hydrofluoric acid is 49%, and the massfraction of described hydrochloric acid is 36.5%, and the massfraction of described nitric acid is 68%.
Preferably, in described step S30, the concrete operations of described pure water cleaning are: added by deionized water in gained solid, after mechanical stirring 30-120 minute, and solid-liquid separation.
Preferably, in described step S30, described mineral acid is hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid.
Further preferably, in described step S30, described mineral acid to be massfraction be 36.5% hydrochloric acid, massfraction be 98% sulfuric acid, massfraction be 68% nitric acid or massfraction be the phosphoric acid of 85%.
Preferably, described step S30 can repeat 2-5 time.
Preferably, in described step S50, the method for described break process is Mechanical Crushing or hand breaking.
Preferably, in described step S50, the material of described rigid non-metallic material and the material of described non-metal mesh are all selected from the one in polypropylene, nylon, terylene, polyethylene and tetrafluoroethylene.
Preferably, in described step S50, the purity of described silica flour is higher than 99.9%.
Preferably, the method for described solid-liquid separation is that centrifugation or press filtration are separated.
The preparation method of the ingot casting silica flour that granularity provided by the invention is controlled, the vacuum tightness of its process of vacuum drying is set to 3.0 × 10
-2-8.0 × 10
-2mpa, between silica flour, the oxidation of reunion and silica flour is all more moderate, can obtain the silica flour that size range is 10 μm of-5cm, in the prior art, usually because the vacuum tightness that arranges of drying process is too high and obtain meticulous silicon powder particle, the meticulous silica flour of this granularity easily melts in ingot casting process; Or because vacuum tightness is too little, silicon powder particle oxidation, reunion seriously, form bulk silicon material, make troubles to subsequent disposal; Vacuum-drying condition provided by the invention can be oxidized and be reunited moderate silica flour, and associating subsequent artefacts or mechanical mill and screening step, namely can obtain the ingot casting silica flour that granularity is controlled;
In addition, repeatedly pickling is adopted to carry out removal of impurities to scrap silicon before vacuum-drying, effectively can remove metallic impurity and reclaim the metal-salt impurity newly brought in dedoping step, wherein, first time hydrofluoric acid and chlorohydric acid pickling not only effectively can remove silica impurity in scrap silicon and part metals impurity, the metallic impurity be wrapped in silica oxides can also be discharged and remove, second time hydrochloric acid and nitric acid acidwashing can be removed metallic impurity remaining in silicon material, and form compact oxidation layer on silicon material surface simultaneously, adding of third time strong acid, the silicate produced in first two steps acid cleaning process can be removed, through three step pickling, surface can be obtained and have compact oxidation layer and the low silica flour material of metals content impurity, not only reach the object of pickling impurity removal, silica flour material surface formed compact oxidation layer can also for follow-up drying phase under vacuum silica flour between zone of oxidation appropriateness reunite provide basis, in addition, grinding and screening process adopt non-metallic material also can avoid again bringing metallic impurity into.Therefore, method provided by the invention not only reaches purifying and reclaims the object of scrap silicon, can obtain granularity and the moderate silica flour for efficient ingot casting of surface oxidation degree simultaneously.
Second aspect, present invention also offers the ingot casting silica flour that a kind of granularity is controlled, the controlled ingot casting silica flour of described granularity can adopt the either method described in first aspect to prepare, and the size range of the ingot casting silica flour that wherein said granularity is controlled is 0.1mm-0.5mm.
The ingot casting silica flour that granularity provided by the invention is controlled, metals content impurity is low, and granularity is controlled, and surface oxidation degree is moderate, the problem that during ingot casting caused because silicon particle size is comparatively thin and surface oxidation degree is low when can avoid ingot casting, silica flour easily melts, can for the preparation of qualified solar energy polycrystal silicon ingot.
The third aspect, present invention also offers the application of the controlled ingot casting silica flour of a kind of granularity as described in relation to the first aspect, and the controlled ingot casting silica flour of described granularity can be used for preparing solar energy polycrystal silicon ingot.
The technique that solar energy polycrystal silicon ingot prepared by the controlled ingot casting silica flour of this granularity of employing provided by the invention is simple, and can obtain high-quality solar energy polycrystal silicon ingot.
The invention provides controlled ingot casting silica flour of a kind of granularity and its preparation method and application and there is following beneficial effect:
(1) preparation method of the ingot casting silica flour that granularity provided by the invention is controlled, have employed 3.0 × 10
-2-8.0 × 10
-2the vacuum tightness of Mpa carries out vacuum-drying, under this vacuum tightness, reunite between silica flour with silica flour and the oxidation of silica flour all more moderate, dried silica flour too carefully also can not can not be gathered into block, after subsequent mechanical or hand breaking also sieve, the silica flour that granularity is controlled can be obtained;
(2) the ingot casting silica flour that granularity provided by the invention is controlled not easily melts when ingot casting, is easy to long brilliant, can obtains the solar energy polycrystal silicon ingot of better quality;
(3) the present invention adopts repeatedly pickling to carry out removal of impurities to scrap silicon, effectively can remove the metal-salt impurity brought in metallic impurity and dedoping step, in addition, the compact oxidation layer introduced at silicon powder surface in acid cleaning process is that the appropriateness reunion of zone of oxidation between follow-up vacuum drying step silica flour provides the foundation, in addition, grinding and screening process adopt non-metallic material also can avoid again bringing metallic impurity in purified and dried silica flour;
(4) the ingot casting silica flour method that granularity provided by the invention is controlled not only reaches the object that purifying reclaims scrap silicon; the silica flour for efficient ingot casting that granularity and surface oxidation degree are suitable for can be obtained simultaneously; its technical process is simple, is easy to large-scale production and uses.
Accompanying drawing explanation
Fig. 1 is the controlled ingot casting silica flour preparation technology schema of granularity provided by the invention;
Fig. 2 is the SEM figure of the controlled ingot casting silica flour of the obtained granularity of embodiment 1.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
Embodiment 1
In conjunction with the ingot casting silica flour preparation technology schema that granularity is as shown in Figure 1 controlled, present embodiments provide the preparation method of the controlled ingot casting silica flour of a kind of granularity, comprise the steps:
S10, be scattered in the water of 20L by 20kg scrap silicon, add the hydrofluoric acid (49%) of 12L and the hydrochloric acid (36.5%) of 8L subsequently, abundant stirring reaction is after 30 minutes, and centrifugation, obtains the elementary silica flour of 14kg;
S20, the elementary silica flour obtained by S10 are scattered in the water of 44L, and add the hydrochloric acid (36.5%) of 10L and the nitric acid (68%) of 2L, dispersed with stirring after 1 hour, then soaks 8 hours, centrifugation, obtains the elementary silica flour of 13.5kg;
S30, the more elementary silica flour of centrifugal for S20 gained to be scattered in the pure water of 20L again, to add the hydrochloric acid (36.5%) of 2L, then dispersed with stirring 1 hour, then centrifugation neutral to pH value by the residual acid solution of pure water cleaning 2 times;
S40, repetition S30 step 2 time, obtain the elementary silica flour of 12.5kg;
S50, the elementary silica flour through S40 process is placed in the vacuum rotary drier of 80 DEG C subsequently, arranging vacuum tightness is 5.0 × 10
-2mpa, obtains the silica flour that 11kg size range is 100 μm of-4cm after dry 10 hours; Underhand polish gained silica flour, the parts contacted with silica flour during grinding adopt polypropylene material, after grinding, gained silica flour sieves through the screen cloth of 30-150 order polypropylene material, finally obtain the ingot casting of 10.9kg size-grade distribution within the scope of 0.1mm-0.5mm silica flour P1, the metal content of described silica flour P1 is 8.3ppm.
Fig. 2 is scanning electron microscope (SEM) figure of the controlled ingot casting silica flour of granularity that the present embodiment provides.
Embodiment 2
A preparation method for the ingot casting silica flour that granularity is controlled, comprises the steps:
S10, be scattered in the water of 36.5L by 40kg scrap silicon, add the hydrofluoric acid (49.5%) of 1.2L and the hydrochloric acid (38%) of 2.3L subsequently, abundant stirring reaction is after 120 minutes, and centrifugation, obtains the elementary silica flour of 30kg;
S20, the elementary silica flour obtained by S10 are scattered in the water of 37.6L, and add the hydrochloric acid (38%) of 0.8L and the nitric acid (67%) of 1.6L, dispersed with stirring after 2 hours, then soaks 10 hours, filtration under diminished pressure, obtains the elementary silica flour of 29.5kg;
S30, the more elementary silica flour of centrifugal for S20 gained to be scattered in the pure water of 29.2L again, to add the nitric acid (67%) of 0.3L, then dispersed with stirring 2 hours, then filtration under diminished pressure neutral to pH value by the residual acid solution of pure water cleaning 2 times;
S40, repetition S30 step 4 time, obtain the elementary silica flour of 27.8kg;
S50, the elementary silica flour through S40 process is placed in the vacuum rotary drier of 30 DEG C subsequently, arranging vacuum tightness is 3.0 × 10
-2mpa, obtains the silica flour that 26kg size range is 200 μm of-5cm after dry 2 hours; Underhand polish gained silica flour, the parts contacted with silica flour during grinding adopt polyester material, after grinding, gained silica flour sieves through the screen cloth of 30-150 order nylon material, finally obtain the ingot casting of 25.8kg size-grade distribution within the scope of 0.1mm-0.5mm silica flour P2, the metal content of described silica flour P2 is 7.8ppm.
Embodiment 3
A preparation method for the ingot casting silica flour that granularity is controlled, comprises the steps:
S10, be scattered in the water of 55L by 3kg scrap silicon, add the hydrofluoric acid (49%) of 4.5L and the hydrochloric acid (36%) of 0.5L subsequently, abundant stirring reaction is after 10 minutes, and centrifugation, obtains the elementary silica flour of 2.25kg;
S20, the elementary silica flour obtained by S10 are scattered in the water of 41L, and add the hydrochloric acid (36%) of 3.3L and the nitric acid (65%) of 0.3L, dispersed with stirring after 0.5 hour, then soaks 0.5 hour, centrifugation, obtains the elementary silica flour of 2.15kg;
S30, the more elementary silica flour of centrifugal for S20 gained to be scattered in the pure water of 42.4L again, to add the sulfuric acid (98%) of 0.6L, then dispersed with stirring 0.5 hour, then centrifugation neutral to pH value by the residual acid solution of pure water cleaning 3 times;
S40, repetition S30 step 5 time, obtain the elementary silica flour of 2kg;
S50, the elementary silica flour through S40 process is placed in the vacuum rotary drier of 120 DEG C subsequently, arranging vacuum tightness is 8.0 × 10
-2mpa, obtains the silica flour that 1.9kg size range is 10 μm of-3.5cm after dry 24 hours; Mechanical mill gained silica flour, the parts contacted with silica flour during grinding adopt polythene material, after grinding, gained silica flour sieves through the screen cloth of 30-150 order tetrafluoroethylene material, finally obtain the ingot casting of 1.85kg size-grade distribution within the scope of 0.1mm-0.5mm silica flour P3, the metal content of described silica flour P3 is 9.6ppm.
For being presented as creativeness of the present invention, the present invention is also provided with comparative example 1 and comparative example 2, wherein, compare with embodiment 1, comparative example 1-2 not in embodiment 1 described in S30 third time acid pickling step, and comparative example 1-2 grinds in the process of silica flour, the parts directly contacted with silica flour adopt common material (stainless steel) in industry, and the material of screen cloth is also common material (stainless steel) in industry; In addition, the vacuum tightness that comparative example 1 process of vacuum drying adopts is 1.0 × 10
-2mpa, the vacuum tightness that comparative example 2 process of vacuum drying adopts is 10.0 × 10
-2mpa.The step of described comparative example 1 and comparative example 2 is as follows:
Comparative example 1
A recovery and treatment method for silica flour, comprises the steps:
S10, be scattered in the water of 20L by 20kg scrap silicon, add the hydrofluoric acid (49%) of 12L and the hydrochloric acid (36.5%) of 8L subsequently, abundant stirring reaction is after 30 minutes, and centrifugation, obtains the elementary silica flour of 15kg;
S20, the elementary silica flour obtained by S10 are scattered in the water of 44L, and add the hydrochloric acid (36.5%) of 10L and the nitric acid (68%) of 2L, dispersed with stirring after 1 hour, then soaks 8 hours, centrifugation, obtains the elementary silica flour of 14.5kg;
S30, repetition S20 step 2 time, obtain the elementary silica flour of 13kg;
S40, the elementary silica flour through S30 process is placed in the vacuum rotary drier of 70 DEG C subsequently, arranging vacuum tightness is 1.0 × 10
-2mpa, the silica flour that 11kg size-grade distribution is 5cm-10cm is obtained after dry 6 hours, gained silica flour is agglomerated into silicon lump, mechanical mill is carried out to gained silica flour, the parts contacted with silica flour during grinding adopt stainless material, after grinding, gained silica flour sieves through the screen cloth of 30-150 order stainless steel, and finally obtain the ingot casting of 10kg size-grade distribution within the scope of 0.1mm-0.5mm silica flour C1, the metal content of described silica flour C1 is 123.5ppm.
Comparative example 2
A recovery and treatment method for silica flour, comprises the steps:
S10, be scattered in the water of 20L by 20kg scrap silicon, add the hydrofluoric acid (49%) of 12L and the hydrochloric acid (36.5%) of 8L subsequently, abundant stirring reaction is after 30 minutes, and centrifugation, obtains the elementary silica flour of 14kg;
S20, the elementary silica flour obtained by S10 are scattered in the water of 44L, and add the hydrochloric acid (36.5%) of 10L and the nitric acid (68%) of 2L, dispersed with stirring after 1 hour, then soaks 8 hours, centrifugation, obtains the elementary silica flour of 13.5kg;
S30, repetition S20 step 2 time, obtain the elementary silica flour of 12kg;
S40, the elementary silica flour through S30 process is placed in the vacuum rotary drier of 70 DEG C subsequently, arranging vacuum tightness is 10.0 × 10
-2mpa, obtains 10kg silica flour C2 after dry 16 hours; Described silica flour C2 is of a size of 5 μm of-25um, and metal content is 110.6ppm.
For the beneficial effect of the ingot casting silica flour that valid certificates granularity provided by the invention is controlled and preparation method thereof, adopt U.S. PE company Optima 7000DV type inductive coupling plasma emission spectrograph to test oxygen level and granular size in the metal content of the silica flour that embodiment 1-3 provided by the invention and comparative example 1-2 obtains, silica flour to contrast, result is as shown in table 1:
The metal content of silica flour prepared by table 1 embodiment 1-3 and comparative example 1-2, oxygen level and granularity
As can be seen from Table 1, the oxygen level of silica flour P1, P2 and P3 that embodiment 1-3 provides is moderate, be respectively 36wt%, 40wt% and 30wt%, and the degree of oxidation of C1 and the C2 product that comparative example provides is respectively 75wt% and 3wt%, facts have proved, the silica flour of 30-40wt% degree of oxidation is very applicable to ingot casting, degree of oxidation is too low, and silica flour agglomerating effect in vacuum drying process is not good, causes silica flour meticulous, easily melt during ingot casting, be unfavorable for long brilliant; Degree of oxidation is too high, and in silica flour, oxygen level is too high, and the Ingot quality that ingot casting obtains is lower, and the yield of silicon ingot and qualification rate can decline, and this illustrates 3.0 × 10 of the present invention's employing
-2mpa-8.0 × 10
-2the dry vacuum pressure of Mpa can significantly improve the quality of silica flour, thus improves quality and the efficiency of silicon ingot;
On the other hand, silica flour P1, size range before P2 and P3 grinding is between 10 μm of-5cm, the silica flour being 0.1mm-0.5mm for follow-up grinding screening prepared sizes provides condition, the granularity of silica flour C1 is 5 μm of-10cm, although also can obtain by follow-up grinding the silica flour that granularity is 0.1mm-0.5mm, but the volume particle size of silica flour C1 take high oxidation degree as cost, because in vacuum drying process, low vacuum makes the high silica flour that causes of air content in dry environment be oxidized seriously, secondly, low vacuum also can make silica flour reunite caking seriously, increase break process difficulty, add the production cost of silica flour, and silica flour C2 granularity is too little, ingot casting process is easily melted and is unfavorable for crystallization, is also unfavorable for ingot casting polycrystal silicon ingot,
In addition, the silica flour metal content that embodiment of the present invention 1-3 provides is low, its content is all less than 10ppm, and silica flour metal content prepared by comparative example 1-2 is more than 110ppm, substantially exceed the silica flour that embodiment of the present invention 1-3 provides, this pickling impurity removal method illustrating that the present invention adopts coordinates non-metallic material grind silica flour and sieve, effectively can not only removing the metallic impurity in scrap silicon, can also effectively preventing following process from silica flour, again mixing the drawback of metallic impurity because adopting metallic substance to grind silica flour and sieve.
To sum up, the degree of oxidation of the silica flour P1-P3 that embodiment of the present invention 1-3 provides and granularity is moderate, metals content impurity is low, is well suited for, for ingot casting solar energy polycrystal silicon ingot, improving efficiency and the good article rate of silicon ingot, thus improves the economic benefit of enterprise.
For illustrating further beneficial effect of the present invention, present invention also offers the embodiment 4 that solar energy polycrystal silicon ingot produced by the ingot casting silica flour adopting the granularity prepared of the present invention controlled, as follows:
Embodiment 4
A method for solar energy polycrystal silicon ingot prepared by the ingot casting silica flour adopting granularity provided by the invention controlled, comprises the steps:
Silica flour P1 the invention process 1 provided is scattered in water, brushes bottom ingot casting crucible after stirring 60min clock; In described ingot casting crucible, load silicon material P1, be placed in ingot furnace, through processes such as fusing, long crystalline substance, annealing and coolings, obtain solar energy polycrystal silicon ingot T1; The silica flour C2 that silica flour C1 comparative example 1 of the present invention provided in the same way and comparative example 2 provide carries out ingot casting respectively, obtained solar energy polycrystal silicon ingot T2 and T3 respectively, the qualification rate of above-mentioned three silicon ingots is compared, and further solar energy polycrystal silicon ingot T1-T3 is cut into slices, and test respectively gained silicon chip be prepared into solar cell after average efficiency, averaging of income battery efficiency and silicon ingot qualification rate as shown in table 2:
The average efficiency of table 2 solar energy polycrystal silicon ingot T1-T3 silicon ingot qualification rate and section gained silicon chip
| Average cell efficiency | Silicon ingot qualification rate | |
| Solar energy polycrystal silicon ingot T1 | 17.3% | 90% |
| Solar energy polycrystal silicon ingot T2 | 17.1% | 85% |
| Solar energy polycrystal silicon ingot T3 | 17.0% | 88% |
As can be seen from Table 2, the solar energy polycrystal silicon ingot T1 of the silica flour P1 ingot casting adopting the embodiment of the present invention 1 to provide, relative to the solar energy polycrystal silicon ingot T2-T3 of the silica flour C1-C2 ingot casting that comparative example 1-2 provides, the silicon ingot qualification rate that silica flour P1 produces is higher, and solar cell prepared by the silicon chip obtained after section has higher average efficiency, this further illustrates the controlled ingot casting silica flour of granularity provided by the invention can for the preparation of efficient solar energy polycrystal silicon ingot.
The above is the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications are also considered as protection scope of the present invention.
Claims (10)
1. a preparation method for the ingot casting silica flour that granularity is controlled, is characterized in that, comprise the following steps:
S10, by scrap silicon dispersed with stirring in pure water, add hydrofluoric acid and hydrochloric acid, regulate solid-liquid weight ratio to be 1:1-1:20, stir after 10-120 minute, carry out solid-liquid separation, obtain elementary silica flour, wherein, described hydrofluoric acid and hydrochloric acid add total amount be the 0.1-2 of described useless silicon material quality doubly;
S20, in described elementary silica flour, add hydrochloric acid and nitric acid, after dispersed with stirring 0.5-2 hour, soak 0.5-10 hour, carry out solid-liquid separation subsequently, obtain solid, wherein, described hydrochloric acid and nitric acid add total amount be the 0.1-2 of described elementary silica flour quality doubly;
S30, by step S20 gained solid dispersal in pure water, add mineral acid, solid-liquid weight ratio is regulated to be 1:1-1:20, after dispersed with stirring 0.5-2 hour, solid-liquid separation, gained solid pure water cleans 2-3 time to pH neutrality, and wherein, the add-on of described mineral acid is 0.01-0.5 times of step S20 gained solid masses;
S40, step S30 gained solid is placed in Vacuumdrier, the vacuum tightness arranging drying machine is 3.0 × 10
-2-8.0 × 10
-2mPa, temperature is 30-120 DEG C, after dry 2-24 hour, obtains silica flour, and the size range of described silica flour is 10 μm of-5cm;
S50, step S40 gained silica flour is carried out break process, sieve with the screen cloth of 30-150 object non-metallic material subsequently, obtain the ingot casting silica flour that size range is 0.1mm-0.5mm, wherein, in the process of described break process, the parts directly contacted with described silica flour adopt rigid non-metallic material.
2. the preparation method of the ingot casting silica flour that a kind of granularity as claimed in claim 1 is controlled, is characterized in that, in described step S10, the volume ratio of described hydrofluoric acid and described hydrochloric acid is 1:2-10:1; In described step S20, the volume ratio of described hydrochloric acid and described nitric acid is 1:2-10:1.
3. the preparation method of the ingot casting silica flour that a kind of granularity as claimed in claim 1 is controlled, is characterized in that, the massfraction of described hydrofluoric acid is 49-50%, and the massfraction of described hydrochloric acid is 36-38%, and the massfraction of described nitric acid is 65-68%.
4. the preparation method of the ingot casting silica flour that a kind of granularity as claimed in claim 1 is controlled, it is characterized in that, in described step S30, the concrete operations of described pure water cleaning are: added by deionized water in gained solid, after mechanical stirring 30-120 minute, solid-liquid separation.
5. the preparation method of the ingot casting silica flour that a kind of granularity as claimed in claim 1 is controlled, is characterized in that, in described step S30, described mineral acid is hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid.
6. the preparation method of the ingot casting silica flour that a kind of granularity as claimed in claim 1 is controlled, is characterized in that, described step S30 can repeat 2-5 time.
7. the preparation method of the ingot casting silica flour that a kind of granularity as claimed in claim 1 is controlled, is characterized in that, in described step S50, the method for described break process is Mechanical Crushing or hand breaking.
8. the preparation method of the ingot casting silica flour that a kind of granularity as claimed in claim 1 is controlled, it is characterized in that, in described step S50, the material of described rigid non-metallic material and the material of described non-metal mesh are all selected from the one in polypropylene, nylon, terylene, polyethylene and tetrafluoroethylene.
9. the ingot casting silica flour that a granularity is controlled, it is characterized in that, the controlled ingot casting silica flour of described granularity can adopt the either method described in claim 1-8 to prepare, wherein, the size range of the ingot casting silica flour that described granularity is controlled is 0.1mm-0.5mm, degree of oxidation is 30-40wt%, and metal content is less than 10ppm.
10. the application of the ingot casting silica flour that granularity as claimed in claim 9 is controlled, is characterized in that, the controlled ingot casting silica flour of described granularity is for the preparation of solar energy polycrystal silicon ingot.
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| CN107337490A (en) * | 2017-06-29 | 2017-11-10 | 镇江环太硅科技有限公司 | A kind of method for starching siliceous fertilizer processed with polycrystalline silicon ingot casting waste material and crystalline silicon cutting waste material |
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| CN105110336A (en) * | 2015-09-15 | 2015-12-02 | 无锡荣能半导体材料有限公司 | Cleaning liquid of silicon material and cleaning method of silicon material |
| CN109663672A (en) * | 2019-01-15 | 2019-04-23 | 国网山东省电力公司电力科学研究院 | A kind of flotation agent and method for floating for isolating pure silicon from smelting product |
| CN111001577A (en) * | 2019-12-09 | 2020-04-14 | 宁晋晶兴电子材料有限公司 | Method for treating silicon scrap |
| CN113697816A (en) * | 2021-10-15 | 2021-11-26 | 北京华威锐科化工有限公司 | Preparation method of silicon powder |
| CN115196637A (en) * | 2022-08-11 | 2022-10-18 | 福建阿石创新材料股份有限公司 | Method for recovering silicon powder for thermal spraying silicon target from residual silicon target |
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