CN102275926B - Recovery method of silicon powder - Google Patents
Recovery method of silicon powder Download PDFInfo
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- CN102275926B CN102275926B CN 201110116082 CN201110116082A CN102275926B CN 102275926 B CN102275926 B CN 102275926B CN 201110116082 CN201110116082 CN 201110116082 CN 201110116082 A CN201110116082 A CN 201110116082A CN 102275926 B CN102275926 B CN 102275926B
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Abstract
The invention relates to a recovery method of silicon powder formed during crystal ingot processing. The method comprises steps that: (1) the silicon powder is mixed with a disperse medium, such that a dispersed suspension is formed; (2) hydro-separation is carried out upon the dispersed suspension obtained in the step (1), such that hydro-separated silicon powder is obtained. With the method provided by the invention, silicon powder can be effectively recovered.
Description
Technical field
The present invention relates to semi-conductor and field of solar energy, especially relate to the recovery method of processing formed silica flour for crystal ingot.
Background technology
It must be cut into wafer in the use procedure of polysilicon and silicon single crystal, and the loss of material is up to more than 40% in the process of cutting, valuable high-purity silicon powder slatterns along with the discarded of slicing slurry.If adopt diamond fretsaw to cut, in slicing slurry, also have the diamond powder of a small amount of costliness, these diamond powders also can slattern along with the discarded of slicing slurry.HIGH-PURITY SILICON is that its production process need to consume a large amount of energy for the starting material of making solar cell.Annual China need to from a large amount of silicon materials of external import, be the material that China is badly in need of.Therefore, how effectively reclaiming silicon and diamond is urgent problem in this area.
Also there is not suitable silica flour to reclaim technique at semi-conductor and solar industry field at present.The main micro-fine steel line drive carborundum powder that adopts of past more than ten years silicon ingot cutting cuts, in the mortar after the cutting except high-purity silicon powder, also has a large amount of carborundum powders and suspension, there are at present some technology can reclaim wherein carborundum powder and suspension, but also do not have suitable recovery technique to obtain highly purified, as to satisfy sun power or semi-conductor industry demand silica flour.Therefore nearly all slicing slurry reclaim wherein carborundum powder and suspension after the silica flour of remaining purity deficiency is all discarded, except wasting, also cause environmental pollution to a certain degree.
Summary of the invention
For this reason, one object of the present invention be to propose a kind of organic efficiency high be used for the recovery method that crystal ingot is processed formed silica flour.
The cutting that diamond fretsaw is used for silicon ingot is just to some extent in batches application in nearest a year, silica flour in the slicing slurry that produces during therefore to diamond wire saw cuts silicon ingot and the recovery of bortz powder not yet have proven technique, need suitable silica flour and the bortz powder recovery technology of brand-new exploitation.The present invention is based on that contriver's following discovery carries out: when utilizing diamond fretsaw cutting silicon ingot, the silica flour that forms is generally very tiny, most of tens of to hundreds of nanometer scale, these tiny powder itself are very easy to reunite, also be easy to reunite together with diamond powder, as shown in Figure 5.Thereby, in order to develop effective silica flour recovery technology, it is highly important that at first to need to solve how the abundant dispersion of the powder (containing silica flour and diamond powder) of these reunions is also further obtained high-purity silica flour and the problem of diamond powder thus.In addition, the contriver finds that also when utilizing diamond fretsaw cutting silicon ingot, the granularity of diamond powder is micron-sized, differs very large with silica flour in granularity, and adamantine density is 3.52g/cm simultaneously
3, the density of silicon is 2.33g/cm
3, thereby can the obvious difference on granularity and density by diamond and silica flour, utilize the waterpower sorting that diamond powder is separated with the silica flour powder.
Thus, according to the recovery method that crystal ingot is processed formed silica flour that is used for of the embodiment of first aspect present invention, may further comprise the steps: mix described silica flour (1) with dispersion medium, formation dispersion suspension liquid; And (2) carry out the waterpower sorting to the suspension that obtains in the step (1), obtains the silica flour through wet concentration.
By above-mentioned for crystal ingot process the recovery method of formed silica flour can be effectively to crystal ingot process silica flour that formed silica flour comprises and other impurity for example bortz powder fully disperse, and then by the waterpower sorting, silica flour is separated with wherein contained other materials, improved the purity of the silica flour that reclaims.
According to embodiments of the invention, the recovery method of processing formed silica flour for crystal ingot can also have following additional technical feature:
According to one embodiment of present invention, described silica flour is for to get by diamond fretsaw crystal ingot machining.
According to one embodiment of present invention, the particle diameter of described silica flour is less than 0.1mm.
According to one embodiment of present invention, described dispersion medium is be selected from water, ethanol, diethanolamine, Virahol, tetrahydrofuran (THF), acetone, dimethyl sulfoxide (DMSO) at least a.
According to one embodiment of present invention, when described dispersion medium was water, it further contained the polyacrylic dispersion agent.
According to one embodiment of present invention, described polyacrylic dispersion agent is poly amic acid.
According to one embodiment of present invention, in described step (2), be 0.001-0.5m/s for the flow velocity of carrying out described waterpower sorting.
According to one embodiment of present invention, in described step (2), in described step (2), in the device of described waterpower sorting, be added with magnet, in order in magnetic field environment, carry out described waterpower sorting.
According to one embodiment of present invention, in the described step (1) with described silica flour with carry out ultrasonic or mechanical stirring after described dispersion medium mixes.
According to one embodiment of present invention, with described silica flour with before described dispersion medium mixes or before the waterpower sorting or after the waterpower sorting, using flotation medium that described silica flour is carried out flotation processes, be lower than the particle of silica flour to separate the density that is comprised in the described silica flour, wherein, the density of described flotation medium is 1.5-2.3g/cm
3
According to one embodiment of present invention, further comprise: the silica flour to described process wet concentration washs, drying, obtains dry silica flour.
According to one embodiment of present invention, described silica flour washing process may further comprise the steps: at first described silica flour through washing is carried out pickling, removing the metallic impurity in the silica flour, and obtain containing the pickle solution of silica flour; Then, the described pickle solution that contains silica flour is carried out solid-liquid separation, separating acid washing lotion and through the silica flour of overpickling; At last, described silica flour through overpickling is washed, to remove the residual acid solution of silicon powder surface.
According to one embodiment of present invention, described pickle solution is selected from one or more in the aqueous solution of mixed solution of mixed solution, sulfuric acid and hydrogen peroxide of hydrochloric acid, sulfuric acid, nitric acid, hydrochloric acid and hydrogen peroxide.
According to one embodiment of present invention, further comprise: the silica flour of described drying is selected from least a processing of electric separation and magnetic separation, the micro-non-conductive particle that wherein comprises with further separation and magnetic substance particle at least a.
According to one embodiment of present invention, further comprise: to the resulting impurity powder of waterpower sorting wash, drying, to obtain diamond powder.
According to one embodiment of present invention, further comprise: described diamond powder is carried out electric separation or magnetic separation, further to isolate the wherein silica flour of conduction, obtain the diamond powder through being further purified.
According to one embodiment of present invention, use pickle solution or alkaline wash to carry out described washing, wherein, described pickle solution is the mixed aqueous solution of hydrofluoric acid and nitric acid, and described alkaline wash is the aqueous solution of potassium hydroxide or sodium hydroxide.
According to one embodiment of present invention, further comprise: use pickle solution or alkaline wash that the diamond powder through electric separation or magnetic separation is washed, wherein, described pickle solution is the mixed aqueous solution of hydrofluoric acid and nitric acid, and described alkaline wash is the aqueous solution of potassium hydroxide or sodium hydroxide.
Additional aspect of the present invention and advantage in the following description part provide, and part will become obviously from the following description, or recognize by practice of the present invention.
Description of drawings
Above-mentioned and/or additional aspect of the present invention and advantage are from obviously and easily understanding becoming the description of embodiment in conjunction with following accompanying drawing, wherein:
Fig. 1 is used for the schematic flow sheet that crystal ingot is processed the recovery method of formed silica flour according to an embodiment of the invention;
Fig. 2 is used for the schematic flow sheet that crystal ingot is processed the recovery method of formed silica flour in accordance with another embodiment of the present invention;
Fig. 3 be according to the present invention another embodiment be used for the schematic flow sheet that crystal ingot is processed the recovery method of formed silica flour;
Fig. 4 be according to the present invention another embodiment be used for the schematic flow sheet that crystal ingot is processed the recovery method of formed silica flour;
Fig. 5 is the silica flour stereoscan photograph that does not carry out dispersion treatment;
Fig. 6 is the silica flour stereoscan photograph through dispersion treatment; And
Fig. 7 is the synoptic diagram that diamond is further carried out purification process according to embodiments of the invention.
Embodiment
The below describes embodiments of the invention in detail, and the example of described embodiment is shown in the drawings, and wherein identical or similar label represents identical or similar element or the element with identical or similar functions from start to finish.Be exemplary below by the embodiment that is described with reference to the drawings, only be used for explaining the present invention, and can not be interpreted as limitation of the present invention.
The recovery method that crystal ingot is processed formed silica flour that is used for of the preparation embodiment of the invention is described below in conjunction with Fig. 1-4.
A) preparation dispersion suspension liquid
According to embodiments of the invention, when formed silica flour reclaims in to the crystal ingot course of processing, at first formed silica flour in the crystal ingot course of processing is mixed with dispersion medium, thus, so that silica flour can be well dispersed in the dispersion medium, obtain dispersion suspension liquid, and then can solve the reluctant problem of some impurity that the agglomeration owing to silica flour causes.
According to embodiments of the invention, can be applied to the present invention fully disperse silica flour dispersion medium kind and be not particularly limited, can be any not with the known solvent of silica flour generation chemical reaction.According to concrete examples more of the present invention, the solvent that adopts is be selected from water, ethanol, diethanolamine, Virahol, tetrahydrofuran (THF), acetone, dimethyl sulfoxide (DMSO) at least a.When these dispersion medium mix with silica flour, not can with silica flour generation chemical reaction, can guarantee that the silica flour that reclaims can be directly used in industrial circle, for example semi-conductor and field of solar energy.In addition, water, ethanol, diethanolamine, Virahol, tetrahydrofuran (THF), acetone, dimethyl sulfoxide (DMSO) can be used as the solvent of multiple solute, and can be compatible mutually with multiple solute, thereby are convenient to subsequent disposal.According to concrete example of the present invention, can adopt one or more mixture of above-mentioned dispersion agent as dispersion medium, for example can adopt the aqueous ethanolic solution of 50% (volume percent) as dispersion medium.According to concrete example of the present invention, when described dispersion medium was water, it further contained the polyacrylic dispersion agent, can be by the polyacrylic dispersant adsorption at silicon powder surface, by the repulsive interaction between the silicon powder surface identical charges, further avoid the gathering between the silica flour.The concrete example of the polyacrylic dispersion agent that can use includes but not limited to ammonium polyacrylate.
According to embodiments of the invention, the silica flour that can process is not particularly limited, and can be by any method crystal ingot to be added resulting silica flour in man-hour, especially by diamond fretsaw silicon ingot is carried out line cutting processing gained.Because the powdery waste main component that produces when by diamond fretsaw silicon ingot being carried out the line cutting processing is silica flour (accounting for about 99.9wt%), the content of bortz powder is lower than thousandth, thereby utilize existing isolation technique, be difficult to silica flour is separated with bortz powder.In addition, although the content of bortz powder is relatively low, work as the silica flour of recovery for the preparation of silicon ingot, when re-starting cutting, the bortz powder that comprises can can't carry out owing to hardness causes greatly cutting, causes waste.And utilize recovery method of the present invention, and can be with adamantine content to ten ten thousand in the recovery silica flour/below (weight ratio), thus the silica flour of being convenient to reclaim has improved industrial value for the preparation of silicon ingot.
In addition, in silica flour, also may exist density to be lower than the impurity of silica flour, for example organic particle.Because can relate to such as guiding resin material, bonded adhesives etc. of organic substance when by diamond fretsaw silicon ingot being carried out the line cutting processing, thereby, can produce organic particle in the process of utilizing diamond fretsaw to cut, these impurity can have adverse influence to the separation of silica flour and the application behind the recovery silica flour.Thereby, with reference to figure 3, according to embodiments of the invention, randomly, with silica flour with before dispersion medium mixes, at first described silica flour is carried out flotation and processes, for example adopt density to be lower than the solution of silica flour density, the optimum flotation medium is that density is 1.5-2.3g/cm
3Solution.Because the density of silica flour is higher than the density of flotation medium, thereby silica flour can accumulate in as sediment the bottom of solution, and the lower composition of density for example the density of organic particle be usually less than 1.5g/cm
3, thereby can swim in the upper strata of flotation medium, thus the lower composition of density that is mingled in the silica flour can be separated with silica flour, improve the purity of the silica flour that reclaims, and then improved the using value of industry.Can be used for the type of flotation medium of the present invention and be not particularly limited, as long as its density is between 1.5-2.3g/cm
3, and do not react with silica flour and get final product.For example can adopt aqueous sulfuric acid, liquor zinci chloridi, calcium bromide solution, zinc bromide solution, calcium iodide solution, ferric chloride Solution, potassium sulfate solution, metatungstic acid ferrous solution as flotation medium.Certainly, it will be appreciated by persons skilled in the art that and use flotation medium that silica flour is carried out the opportunity of above-mentioned processing and be not particularly limited.Also can use flotation medium that silica flour is carried out flotation before carrying out the waterpower sorting or after the waterpower sorting and process, condition and employed flotation medium are ditto described, repeat no more herein.
In addition, according to embodiments of the invention, can dispersion suspension liquid be stirred in that silica flour and dispersion medium are mixed to get in the process of dispersion suspension liquid, for example adopt ultrasonic agitation or mechanical stirring.By adopting stir process, can improve the degree of scatter of silica flour in dispersion medium, the applicant finds can reduce thus the granularity of particle that silica flour forms, avoid silica flour in dispersion suspension liquid, to reunite, thereby avoided being difficult to remove some and being swept along wherein impurity bortz powder for example owing to silica flour gathers into macrobead.Because the silicon particle size that the line cutting obtains is all smaller, be very easy to and other particles such as diamond particles etc. reunited together, is difficult to separately.By stir process, for example adopt ultrasonic agitation can avoid the generation of problems.
B) waterpower sorting
Waterpower is sorted on current that herein implication refers to have certain speed when the dispersion suspension liquid that contains silica flour and other impurity is impacted, the difference on density/granularity by silica flour and other impurity, so that silica flour is different from the velocity of flow of other impurity, thereby realized separating of silica flour and other impurity.The contriver also finds, when utilizing diamond fretsaw cutting silicon ingot, the granularity of diamond powder is micron-sized, differ very large with the silica flour of Nano grade in granularity, thereby can the obvious difference on granularity by diamond and silica flour, utilize the waterpower sorting that diamond powder is separated with the silica flour powder.According to embodiments of the invention, equipment and the method for carrying out the waterpower sorting are not subjected to any special restriction, as long as can effectively carry out separating of silica flour and other impurity.Also can adopt ripe in the market waterpower size separation equipment to be used for separation of the present invention, concrete parameter can be selected according to the physical properties of silica flour and other impurity and with reference to the user manual of waterpower size separation equipment.According to one embodiment of present invention, adopt the flow velocity of 0.001-0.5m/s that the dispersion suspension liquid that contains silica flour and other impurity is processed, thus, can effectively separate silica flour, obtain the silica flour through wet concentration.
According to concrete example of the present invention, before the silica flour in the dispersion suspension liquid and diamond powder are carried out the waterpower sorting, can carry out preliminary enrichment to treating waterpower sorting material in the dispersion suspension liquid, thereby improve the efficient of water conservancy sorting.For this reason, according to embodiments of the invention, before dispersion suspension liquid is carried out the waterpower sorting, dispersion suspension liquid is left standstill certain hour, thereby can be so that the silica flour in the dispersion suspension liquid and other impurity can the part sedimentations, thus be convenient to the carrying out of waterpower sorting, improve the efficient of waterpower sorting.In addition, also can adopt other means, for example dispersion suspension solution tentatively be filtered.
In addition, the applicant finds: normal operation artificial diamond stone flour in diamond fretsaw, synthesizing take carbon element as raw material of synthetic diamond, alloy is catalyst, its crystals often contains catalyst alloy inclusion such as Co, Ni, the Fe etc. of some amount, so that man-made diamond has certain magnetic, and silica flour does not have magnetic.According to one embodiment of present invention, in the device of described waterpower sorting, be added with magnet, be among the magnetic field so that carry out the aqueous solution of waterpower sorting, thus, in magnetic field environment, implement sorting in the water.The magnetic metal-powder of tool of the magnetic powder of tool such as bortz powder and trace is helped separating of silica flour and bortz powder especially by magnet absorption in the aqueous solution.According to concrete example of the present invention, below wet concentration equipment, magnet is set, can further facilitate thus and implement wet concentration separation silica flour and diamond powder.According to embodiments of the invention, the type of magnet is not particularly limited, and for example includes but not limited to permanent magnet, electromagnet.According to concrete example of the present invention, adopt permanent magnet, for example have ferromagnetic Nd-Fe-B permanent magnet.Thus, can further improve by magnet and promote the effect that wet concentration separates, and can save electric energy, saving cost.
C) subsequent disposal
According to embodiments of the invention, can obtain the silica flour through super-dry by washing, drying from the silica flour through wet concentration.Particularly, according to specific examples of the present invention, the washing process that can adopt comprises that at first the silica flour through wet concentration is carried out pickling removes metallic impurity in the silica flour, carries out afterwards the silica flour through overpickling is washed, and removes the residual acid solution of silicon powder surface.
Concrete, according to embodiments of the invention, the washing process that can adopt may further comprise the steps: at first described silica flour through wet concentration is carried out pickling, removing the metallic impurity in the silica flour, and obtain containing the pickle solution of silica flour; Then, the described pickle solution that contains silica flour is carried out solid-liquid separation, separating acid washing lotion and through the silica flour of overpickling; At last, described silica flour through overpickling is washed, to remove the residual acid solution of silicon powder surface.According to embodiments of the invention, process the particle diameter of the silica flour that obtains afterwards less than 0.1mm through separation, washing, dry step.For example according to embodiments of the invention, can adopt in the aqueous solution of mixed solution of the mixed solution, sulfuric acid and the hydrogen peroxide that are selected from pickle solution and are selected from hydrochloric acid, sulfuric acid, nitric acid, hydrochloric acid and hydrogen peroxide one or more to carry out pickling.Thus, can effectively remove the metallic impurity that are attached to silicon powder surface, and can not cause damage to silica flour self.Be not particularly limited for the method and apparatus that carries out solid-liquid separation, particularly, can carry out solid-liquid separation by centrifugation by whizzer, also can use the mode of filtering.
Further, according to embodiments of the invention, can be from through waterpower sorting resulting impurity powder separation diamond powder, particularly, and can be by to washing through the resulting impurity powder of waterpower sorting and dry, thus diamond powder obtained.In addition, according to one embodiment of present invention, the impurity powder that can be at first obtain the sorting through waterpower screens, and obtains diameter less than 50 microns bortz powder (being generally the 1-20 micron), i.e. diamond meal.Further, because diamond is isolator, the particles such as other glass, plastics also are isolator, and silica flour is semi-conductor (resistivity is the 0.001-100 ohmcm), thereby can process by electric separation, so that these nonconducting impurity particles separate with silica flour.As previously mentioned, man-made diamond has certain magnetic, and silica flour does not have magnetic, therefore, can magnetic separation separate between diamond and the silica flour.Thus, be further purified diamond powder, and Separation and Recovery part silica flour.
Because the ratio of diamond powder in the raw material silica flour is lower, is usually less than thousandth, thereby usually separating can residual a part of silica flour in the diamond powder that obtains.Thus, according to one embodiment of present invention, after the silica flour that obtains respectively diamond powder and drying, with reference to figure 7, can carry out further purifying treatment to diamond powder and silica flour by electric separation and/or the magnetic separation means of routine, further to remove the impurity in silica flour or the diamond powder.Thus, can the silica flour with drying in residual non-conductive impurity particle remove, improve the purity of silica flour, and the silica flour of conduction remaining in the diamond powder removed, to improve the purity of diamond powder.In addition, after diamond powder is carried out electric separation or magnetic separation, can isolate highly purified silica flour, thereby improve the rate of recovery of silica flour.In addition, for through electric separation or the resulting diamond powder of magnetic separation, can also be further purified, for example by using pickle solution or alkaline wash that diamond powder is washed, thus, can remove by chemical reaction a small amount of silica flour of the remnants that adhere on the diamond powder.It will be appreciated by those skilled in the art that can only carry out electric separation or magnetic separation and pickling or alkali cleaning to diamond powder one of processes, perhaps all carry out that this depends on the content of contained remaining silica flour in the diamond powder.If silica flour content is higher, can at first adopt electric separation or magnetic separation to carry out diamonds separated powder and silica flour, can reclaim a large amount of silica flours thus.If silica flour content is lower, can directly carry out pickling or alkali cleaning, thereby to remove silica flour purifying diamond powder.The condition of diamond powder being carried out pickling or alkali cleaning is not particularly limited, and according to concrete example, the pickle solution that can adopt is the mixed aqueous solution of hydrofluoric acid and nitric acid, and the alkaline wash that can adopt is the aqueous solution of potassium hydroxide or sodium hydroxide.The temperature of carrying out pickling and alkali cleaning also is not particularly limited, in order to improve the efficient of pickling and alkali cleaning, according to concrete example of the present invention, can carry out pickling or alkali cleaning under the temperature of room temperature being higher than, for example under 60-90 degree centigrade temperature, according to concrete example of the present invention, under 80 degrees centigrade, diamond powder is carried out alkali cleaning.
According to embodiments of the invention, the method and apparatus that can carry out electric separation or magnetic separation is not particularly limited.Can according to the processing sample, adjust the strength of electric field or the magneticstrength that apply when carrying out electric separation or magnetic separation processing, in order to be enough to so that silica flour fully separates with the diamond powder that is mingled in wherein.Can be any method as known in the art for electric separation of the present invention or magnetic selection method.On market, also there are many very ripe electric separations or magnetic separation instrument selective.The user can select suitable condition to carry out preliminary sorting according to the specification sheets of product according to conditions such as the granularity of the silica flour of required separation and diamond powder, quality to obtain through the silica flour of preliminary sorting and contain the impurity of diamond powder.According to embodiments of the invention, the electric separation that can adopt is to be selected from drum electric separation, cell-type electric separation, freely to fall at least a of electric separation, saddle type electric separation, belt-type electric separation, disc type electric separation, shaking-table electric separation or whirlwind-type electric separation.According to embodiments of the invention, the magnetic separator that can adopt is be selected from belt magnetic separator, drum magnetic separator, roll-type magnetic separator, disk-type magnetic separator, ring magnetic separator, cage magnetic separator or magnetic-pulley separator at least a, magnetic source wherein can be Magnets, also can be the electromagnetism magnetic source.
D) industrial applicibility
According to embodiments of the invention, content by the resulting final silica flour product of method of the present invention has reached more than the 99.99wt%, the rate of recovery can reach 50-80%, can reclaim a large amount of silica flours thus, and can directly the silica flour that reclaims be used for industrial application.According to embodiments of the invention, the particle diameter of the silica flour that process separation, washing, dry step obtain after processing is generally the silica flour of Nano grade less than 0.1mm.The electrode that the silica flour of these recovery can be used for the making fuel cell replaces carbon dioxide process carbon electrode, is reused for the making silicon ingot.
Further, can reclaim by method of the present invention and to obtain highly purified bortz powder, the content of resulting bortz powder has reached more than the 99.9wt%, the rate of recovery can reach 60-90%, can reclaim a large amount of bortz powders thus, and can directly the bortz powder that reclaims be used for industrial application.According to embodiments of the invention, be generally micron level through the bortz powder that separates, washs, dry step obtains after processing.The bortz powder of these recovery can be used for make diamond fretsaw.
The concrete example of following basis describes the recovery method of processing formed silica flour for crystal ingot of the present invention, and concrete example is not made any restriction to scope of the present invention.
Example 1
The silica flour (500 gram) that utilizes diamond fretsaw cutting silicon ingot to produce is joined in 1 premium on currency (dispersion agent), and ultrasonic agitation was processed 5 minutes, obtained therein finely dispersed dispersion suspension liquid of silica flour.Utilize speed for the current of 0.5m/s dispersion suspension liquid to be carried out the waterpower sorting, obtain silica flour and impurity powder through wet concentration, the silica flour through wet concentration is carried out salt acid elution, washing, vacuum-drying obtain silica flour.Be lower than 10ppm through detecting the content that is insoluble to the solid matter (mainly being bortz powder) of hydrofluoric acid/salpeter solution in the silica flour that reclaims.In addition, the impurity powder is carried out aqueous sodium hydroxide washes wash and wash, drying obtains diamond powder.Extract sample from described dispersion suspension liquid and carry out scanning electron microscope and detect, the result as shown in Figure 6, silica flour has obtained abundant dispersion.
Example 2
It is 1.5g/cm that the silica flour (500 gram) that utilizes diamond fretsaw cutting silicon ingot to produce is joined density
3Sulphuric acid soln (flotation medium) in carry out flotation, be recovered in the silica flour of solution bottom, join after the washing in 1 liter of 50% ethanolic soln (dispersion agent), ultrasonic agitation was processed 5 minutes, obtained therein finely dispersed dispersion suspension liquid of silica flour.Utilize speed for the current of 0.3m/s dispersion suspension liquid to be carried out the waterpower sorting, obtain silica flour and impurity powder through wet concentration, the silica flour through wet concentration is carried out salt acid elution, washing, vacuum-drying obtain dry silica flour.The silica flour of drying joined carry out electric separation in the electric separation instrument, be lower than 10ppm through detecting the content that is insoluble to the solid matter of hydrofluoric acid/aqueous nitric acid in the silica flour that reclaims.In addition, the impurity powder is carried out aqueous sodium hydroxide washes wash and wash, drying obtains diamond powder.
Example 3
It is 1.6g/cm that the silica flour (500 gram) that utilizes diamond fretsaw cutting silicon ingot to produce is joined density
3Ferric chloride in aqueous solution (flotation medium) in carry out flotation, be recovered in the silica flour of solution bottom, join after the washing in 1 liter of tetrahydrofuran (THF) (dispersion agent), ultrasonic agitation was processed 5 minutes, obtained therein finely dispersed dispersion suspension liquid of silica flour.Utilize speed for the current of 0.1m/s dispersion suspension liquid to be carried out the waterpower sorting, obtain silica flour and impurity powder through wet concentration, the silica flour through wet concentration is carried out salt acid elution, washing, vacuum-drying obtain dry silica flour.The silica flour of drying joined carry out electric separation in the electric separation instrument, be lower than 10ppm through detecting the content that is insoluble to the solid matter of hydrofluoric acid/nitric acid mixed aqueous solution in the silica flour that reclaims.The impurity powder joined carry out magnetic separation in the magnetic separation instrument, obtain the diamond powder through magnetic separation, and further reclaimed silica flour.
Example 4
It is 1.6g/cm that the silica flour (500 gram) that utilizes diamond fretsaw cutting silicon ingot to produce is joined density
3Solution of calcium bromide in water (flotation medium) in carry out flotation, be recovered in the silica flour of solution bottom, join after the washing in 1 liter of dimethyl sulfoxide (DMSO) (dispersion agent), ultrasonic agitation was processed 5 minutes, obtained therein finely dispersed dispersion suspension liquid of silica flour.Utilize speed for the current of 0.01m/s dispersion suspension liquid to be carried out the waterpower sorting, obtain silica flour and impurity powder through wet concentration, the silica flour through wet concentration is carried out salt acid elution, washing, vacuum-drying obtain dry silica flour.The silica flour of drying joined carry out electric separation in the electric separation instrument, be lower than 10ppm through detecting the content that is insoluble to the solid matter of hydrofluoric acid/aqueous nitric acid in the silica flour that reclaims.In addition, the impurity powder is carried out salt acid elution and washing, drying obtains diamond powder.Diamond powder joined carry out electric separation in the electric separation instrument, obtain the diamond powder through electric separation, and reclaimed silica flour.Then, utilize sodium hydroxide under 80 degrees centigrade, to carry out alkali cleaning to the diamond powder through electric separation, thus the diamond powder that acquisition is further purified.
Example 5
It is 1.6g/cm that the silica flour (500 gram) that utilizes diamond fretsaw cutting silicon ingot to produce is joined density
3Solution of calcium bromide in water (flotation medium) in carry out flotation, be recovered in the silica flour of solution bottom, join after the washing in 1 liter of dimethyl sulfoxide (DMSO) (dispersion agent), ultrasonic agitation was processed 5 minutes, obtained therein finely dispersed dispersion suspension liquid of silica flour.Utilize speed for the current of 0.01m/s dispersion suspension liquid to be carried out the waterpower sorting, obtain silica flour and impurity powder through wet concentration, the silica flour through wet concentration is carried out salt acid elution, washing, vacuum-drying obtain dry silica flour.The silica flour of drying joined carry out electric separation in the electric separation instrument, be lower than 10ppm through detecting the content that is insoluble to the solid matter of hydrofluoric acid/aqueous nitric acid in the silica flour that reclaims.In addition, the impurity powder is carried out salt acid elution and washing, drying obtains diamond powder.Diamond powder joined carry out magnetic separation in the magnetic separation instrument, obtain the diamond powder through magnetic separation, and reclaimed silica flour.Then, utilize sodium hydroxide under 80 degrees centigrade, to carry out alkali cleaning to the diamond powder through electric separation, thus the diamond powder that acquisition is further purified.
In the description of this specification sheets, the description of reference term " embodiment ", " some embodiment ", " example ", " concrete example " or " some examples " etc. means to be contained at least one embodiment of the present invention or the example in conjunction with specific features, structure, material or the characteristics of this embodiment or example description.In this manual, the schematic statement of above-mentioned term not necessarily referred to identical embodiment or example.And the specific features of description, structure, material or characteristics can be with suitable mode combinations in any one or more embodiment or example.
Although illustrated and described embodiments of the invention, those having ordinary skill in the art will appreciate that: can carry out multiple variation, modification, replacement and modification to these embodiment in the situation that does not break away from principle of the present invention and aim, scope of the present invention is limited by claim and equivalent thereof.
Claims (15)
1. one kind is used for the recovery method that crystal ingot is processed formed silica flour, it is characterized in that, may further comprise the steps:
(1) described silica flour is mixed with dispersion medium, form dispersion suspension liquid; And
(2) the dispersion suspension liquid that obtains in the step (1) is carried out the waterpower sorting, obtain silica flour and impurity powder through wet concentration;
Wherein, in described step (2), be 0.01-0.5m/s for the flow velocity of carrying out described waterpower sorting.
2. recovery method according to claim 1 is characterized in that, described silica flour is to silicon ingot cutting processing gained by diamond fretsaw.
3. recovery method according to claim 1 is characterized in that, the particle diameter of described silica flour is less than 0.1mm.
4. recovery method according to claim 1 is characterized in that, described dispersion medium is be selected from water, ethanol, diethanolamine, Virahol, tetrahydrofuran (THF), acetone, dimethyl sulfoxide (DMSO) at least a.
5. recovery method according to claim 4 is characterized in that, when described dispersion medium was water, it further contained the polyacrylic dispersion agent.
6. recovery method according to claim 5 is characterized in that, described polyacrylic dispersion agent is ammonium polyacrylate.
7. recovery method according to claim 1 is characterized in that, in described step (2), is added with magnet in the device of described waterpower sorting, in order to carry out described waterpower sorting in magnetic field environment.
8. recovery method according to claim 1 is characterized in that, in the described step (1) with described silica flour with carry out ultrasonic or mechanical stirring after described dispersion medium mixes.
9. recovery method according to claim 1, with described silica flour with before described dispersion medium mixes or before the waterpower sorting or after the waterpower sorting, using flotation medium that described silica flour is carried out flotation processes, be lower than the particle of silica flour to separate the density that is comprised in the described silica flour, wherein, the density of described flotation medium is 1.5-2.3g/cm
3
10. recovery method according to claim 1 is characterized in that, further comprises:
Silica flour to described process wet concentration washs, drying, obtains dry silica flour.
11. recovery method according to claim 10 is characterized in that, described silica flour washing process may further comprise the steps:
At first, described silica flour through wet concentration is carried out pickling, removing the metallic impurity in the described silica flour, and obtain containing the pickle solution of silica flour;
Then, the described pickle solution that contains silica flour is carried out solid-liquid separation, separating acid washing lotion and through the silica flour of overpickling;
At last, described silica flour through overpickling is washed, with the residual acid solution of removal silicon powder surface,
Wherein, described pickle solution is selected from one or more in the aqueous solution of mixed solution of mixed solution, sulfuric acid and hydrogen peroxide of hydrochloric acid, sulfuric acid, nitric acid, hydrochloric acid and hydrogen peroxide.
12. recovery method according to claim 10 is characterized in that, further comprises:
The silica flour of described drying is selected from least a processing of electric separation and magnetic separation, the micro-non-conductive particle that wherein comprises with further separation and magnetic substance particle at least a.
13. recovery method according to claim 1 is characterized in that, further comprises:
To the resulting impurity powder of waterpower sorting wash, drying, to obtain diamond powder.
14. recovery method according to claim 13 is characterized in that, further comprises:
Described diamond powder is carried out electric separation or magnetic separation, to be further purified described diamond powder.
15. according to claim 13 or 14 described recovery methods, it is characterized in that, use pickle solution or alkaline wash that described impurity powder is carried out described washing, wherein, described pickle solution is the mixed aqueous solution of hydrofluoric acid and nitric acid, and described alkaline wash is the aqueous solution of potassium hydroxide or sodium hydroxide; Perhaps
Use pickle solution or alkaline wash that the diamond powder through electric separation or magnetic separation is washed, wherein, described pickle solution is the mixed aqueous solution of hydrofluoric acid and nitric acid, and described alkaline wash is the aqueous solution of potassium hydroxide or sodium hydroxide.
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| CN103373731B (en) * | 2012-04-12 | 2015-07-15 | 江西赛维Ldk太阳能高科技有限公司 | Method for recycling silicon powder from diamond wire cutting slurry |
| CN102814297A (en) * | 2012-08-13 | 2012-12-12 | 安阳市凤凰光伏科技有限公司 | Cleaning solution for separating silicon material in manner of sedimentation and preparation and application method of cleaning solution |
| CN103528874A (en) * | 2013-09-26 | 2014-01-22 | 镇江耐丝新型材料有限公司 | Separating method of carborundum particles on surface of diamond wire |
| JP6448955B2 (en) * | 2014-09-01 | 2019-01-09 | 株式会社ディスコ | Silicon powder recovery method and silicon powder recovery device |
| CN105693250B (en) * | 2016-01-22 | 2018-08-28 | 东北大学 | A method of preparing boron carbide Ultramicro-powder with sapphire smooth grinding slug |
| CN105692624B (en) * | 2016-03-22 | 2018-08-21 | 苏州协鑫光伏科技有限公司 | The recovery method of silicon material in the useless cutting slurries of silicon wafer cut by diamond wire |
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| CN101823712A (en) * | 2010-04-02 | 2010-09-08 | 河南新大新材料股份有限公司 | Recovery processing method of silicon slice cut waste mortar |
| CN101823716A (en) * | 2010-03-09 | 2010-09-08 | 江西赛维Ldk太阳能高科技有限公司 | Method for separating silica powder and impurities in mixture |
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| CN101823716A (en) * | 2010-03-09 | 2010-09-08 | 江西赛维Ldk太阳能高科技有限公司 | Method for separating silica powder and impurities in mixture |
| CN101823712A (en) * | 2010-04-02 | 2010-09-08 | 河南新大新材料股份有限公司 | Recovery processing method of silicon slice cut waste mortar |
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