CN101941699B - Method for reclaiming silicon and silicon carbide from cutting waste materials of monocrystalline silicon and polycrystalline silicon - Google Patents
Method for reclaiming silicon and silicon carbide from cutting waste materials of monocrystalline silicon and polycrystalline silicon Download PDFInfo
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Abstract
The invention relates to a method for reclaiming silicon and silicon carbide from cutting waste materials of monocrystalline silicon and polycrystalline silicon. The method comprises the following steps of: mixing and stirring hydrochloric acid and dried cutting powder and filtering the mixture through water washing; placing an upper layer solvent and a lower layer solvent into a separation column; adding the preprocessed micropowder into the separation column from the upper part of the separation column, standing for settling, releasing a mixture of the upper solvent and the silicon, releasing a mixture of the lower layer solvent and the silicon carbide, reclaiming the silicon and the silicon carbide respectively by a filtering method through water washing, and reclaiming the solvents; and filtering the reclaimed silicon powder and the silicon carbide powder through water washing and drying the silicon powder and the silicon carbide powder respectively. The method has the advantages that: the purity of the silicon in the refined powder can reach 93 percent and the purity of the reclaimed silicon carbide can reach 86 percent through extraction separation and enrichment; impurity elements harmful to the properties of the high-purity silicon are not introduced; and the process is simple and practicable and equipment is mature.
Description
Technical field
The invention belongs to the silicon materials technical field, be specifically related to the solar-grade polysilicon technology.
Background technology
After the mankind got into 21 century, along with the fast development of semi-conductor industry, the high-purity crystal silicon materials had obtained widespread use, and wherein crystalline silicon is to be drawn as silicon single crystal rod earlier, cuts into silicon chip then and is used to make chip.In addition; In recent years; Along with global oil, coal equal energy source growing tension, sun power becomes most important new forms of energy in this century because of inexhaustible, nexhaustible, clean environment firendly, unique advantage such as safe and reliable, and the solar energy industry in the whole world has got into high-speed development period.But at present, the cost of solar electrical energy generation is still higher, and reason is that the polysilicon of preparation solar cell is very expensive.The main method of preparation solar-grade polysilicon is the improvement Siemens Method at present; Also inreal this technological core of grasping of China; External major company has monopolized technology, market and price, and the polysilicon price of China's import in 2008 is 400 dollars/kilogram, has reached 480 dollars/kilogram in the time of the highest.In short supply and the expensive development that seriously restricts China's photovoltaic industry of polysilicon.
When the preparation solar cell; Need HIGH-PURITY SILICON be cast polycrystal silicon ingot; Cut into silicon chip then; So no matter be used silicon single crystal of semi-conductor industry or the used polysilicon of sun power, all need high-purity crystalline silicon be cut into silicon chip, in cutting process, produce a large amount of cutting slugs.In when cutting, calculate by theory and to have 44% crystalline silicon and cut mill and cut in the liquid for high-purity silicon powder gets into, lost and have in the actual course of processing up to the crystalline silicon of 50-52% form with silica flour.No matter being used for semiconductor grade silicon single crystal or being used for solar-grade polysilicon all is to make through high energy consumption and high cost.If can the HIGH-PURITY SILICON in the slug, polyoxyethylene glycol and silit be carried out comprehensive reutilization, this will reduce environmental pollution, improve the utilization ratio of resource.Particularly if can the HIGH-PURITY SILICON in the cutting slurry be able to reclaim effectively and be used further to make solar cell, be highly significant to the import volume in short supply, that reduce polysilicon of alleviating China's solar energy polycrystalline silicon, and this will create huge economic benefit.
To the recovery of silicon single crystal and polysilicon cutting slug, correlative study personnel do a lot of work, and applied for relevant patent.In the recovery method and patent of cutting slug, most of method all is polyoxyethylene glycol and the silit that reclaims in the slip, and ripe not enough for the recovery method of HIGH-PURITY SILICON in the cutting slurry.Existing main recovery technical process is as shown in Figure 1.
Can find out from present recovery situation; Comprehensive recovery for the cutting waste material moves to maturity the stage, and part enterprise in Henan has also made the equipment that reclaims the cutting waste material, has all reached more satisfactory effect for the recovery of cutting liquid, silit, polyoxyethylene glycol; And can realize industrial treatment; It is unsatisfactory that but HIGH-PURITY SILICON wherein reclaims, and this is because some physical properties of silicon and silit is similar, separation difficulty.And the composition of valency is arranged in the cutting waste material most is silicon wherein; Content is higher, in order to reclaim effectively, improves the utilization ratio of resource; Dalian University of Technology, Northeastern University, Taiwan Univ. etc. and abroad some researchists carried out research in succession and explored; Attempt to reclaim the HIGH-PURITY SILICON in the cutting waste material, research has obtained certain effect, but does not see the industriallization report.
Summary of the invention
To the weak point that above prior art exists, it is a kind of by the method that reclaims silicon and silit in silicon single crystal and the polysilicon cutting waste material that the present invention provides, and simplifies silicon single crystal and polycrystalline silicon material and reclaim technology, thereby alleviate the in short supply of silicon single crystal and polycrystalline silicon material.
Scheme of the present invention is:
(1) slip pre-treatment
With silicon single crystal and the oven dry of polysilicon cutting waste material; Then the cutting powder after hydrochloric acid and the oven dry is mixed; Be mixed with the suspension liquid system; In temperature is stir process 8～15 hours under 40～70 ℃, condition of normal pressure, and the suspension liquid system that obtains is washed suction filtration, obtains the mixture micro mist of silicon and silit;
(2) solvent assembling
Extracting and separating is carried out in separator column, and described separator column is for having the end, open glass cylinder, and its inner bottom surface diameter is 100mm～200mm, highly is 1500～2500mm; On the separator column sidewall, apart from top 600mm～1200mm a valve is installed, is middle valve, distance tube end upper limb 0～60mm place also is equipped with a valve on the separator column sidewall, is the bottom valve.The solvent of selecting is: the upper strata solvent is that trichloromethane, lower floor's solvent are tetracol phenixin; Or the upper strata solvent is that epoxy chloropropane, lower floor's solvent are diazomethane; Or the upper strata solvent is that acetate, lower floor's solvent are tetracol phenixin; Or the upper strata solvent is that acetone, lower floor's solvent are trichloromethane;
Earlier lower floor's solvent is added separator column, the upper strata solvent is slowly added in the separator column along separating post jamb, left standstill after adding 1～2 minute;
(3) extracting and separating
The silicon that obtains after step (1) processing and the mixture micro mist of silit are added from separator column top; After the mixture micro mist all added; Standing sedimentation 10～15 minutes is opened the middle valve of separator column, emits the mixture of upper strata solvent and silicon; Adopt the washing method of pumping filtration to reclaim silicon, and separate the upper strata solvent; Open the bottom valve of separator column, emit the mixture of lower floor's solvent and silit, adopt the washing method of pumping filtration to reclaim silit, and separate lower floor's solvent;
The washing suction filtration adopts the vacuum filtration device, requires filtering accuracy to reach 0.1 μ m, and the mixture of upper strata solvent and silicon is carried out suction filtration, obtains filter cake and upper strata solvent, repeats following process 2～5 times then:
In filter cake, add deionized water, stir, obtain suspension liquid, count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount, and this suspension liquid is carried out vacuum filtration, obtains filter cake;
Mixture to lower floor's solvent and silit carries out suction filtration, obtains filter cake and lower floor's solvent, repeats following process 2～5 times then: in filter cake, add deionized water; Stir; Obtain suspension liquid, count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount; This suspension liquid is carried out vacuum filtration, obtain filter cake;
(4) reclaim solvent
Step (3) is separated the upper strata solvent cycle utilization that obtains; Step (3) is separated the lower floor's solvent that obtains and is contained a spot of upper strata solvent, and step (3) is separated the lower floor's solvent air distillation that obtains, and distillation temperature is the boiling point of low boiling point solvent; Separate upper strata solvent and lower floor's solvent, recycling;
(5) powder is purified
Filter cake to step (3) obtains is washed suction filtration more respectively, and the filter cake that the washing suction filtration obtains is at last dried respectively, obtains silica flour and carborundum powder respectively.
The concrete process step of the inventive method is following.
(1) slip pre-treatment
Silicon single crystal and polysilicon are cut waste material 280～320 ℃ of oven dry, and drying time is 20～30 minutes, stops to smolder to powder and is advisable, and mainly removes water and polyoxyethylene glycol in the waste material; Then with mass concentration be 10%～15% hydrochloric acid with oven dry after the cutting powder be 4: 1 mixed by liquid, solid volume ratio; Be mixed with the suspension liquid system; In temperature is stir process 8～15 hours under 40～70 ℃, condition of normal pressure; 300～3000 rev/mins of stir speed (S.S.)s are removed iron and oxide compound thereof in the cutting waste material; The suspension liquid system that obtains is washed suction filtration, further remove iron and other impurity element of free state, obtain the mixture micro mist of silicon and silit.
The washing suction filtration adopts vacuum filtration device commonly used; Require filtering accuracy to reach 0.1 μ m; Earlier the suspension liquid after the stir process under above-mentioned 40～70 ℃, condition of normal pressure is carried out suction filtration, obtain filter cake, repeat following process 2～5 times then: in filter cake, add deionized water; Stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(2) solvent assembling
Extracting and separating is carried out in separator column, and separator column is for having the end, open glass cylinder (as shown in Figure 2), and its inner bottom surface diameter is 100mm～200mm, highly is that 1500～2500mm (is D=100mm～200mm, H=1500mm～2500mm).On the separator column sidewall, apart from top 600mm～1200mm a valve being installed (is H1=600mm～1200mm); Be middle valve; A valve also is installed (is H2=0～60mm), be the bottom valve at distance tube end upper limb 0～60mm place on the separator column sidewall.
On physical properties, exist certain difference at the two kinds of material silicon and the silit of cutting in the waste material; The density of silicon is less than the density of silit, and polarity is slightly larger than silit, is prone in polar solvent, reach sedimentation equilibrium according to the big material of polarity; The material that polarity is little is prone in polar solvent, sink fast; And the little fast principle of material sedimentation that the material sedimentation is slow, density is big of density, select the solvent of two kinds of opposed polarities and density to carry out extracting and separating, two kinds of solvents are in the upper and lower in the separator column respectively; Selection principle is: the upper strata solvent polarity is big, density is little, selects epoxy chloropropane, benzene, toluene, acetone, trichloromethane or acetate; Lower floor's solvent polarity is little, density is big, selects tetracol phenixin, diazomethane, trichloromethane or USP Kosher; In the matching process of two kinds of reagent, to take all factors into consideration the factors such as viscosity coupling between the time of micro mist in settling process, the two kinds of solvents.The solvent coupling that the present invention selects is: the upper strata solvent is that trichloromethane, lower floor's solvent are tetracol phenixin; The upper strata solvent is that epoxy chloropropane, lower floor's solvent are diazomethane; The upper strata solvent is that acetate, lower floor's solvent are tetracol phenixin; The upper strata solvent is that acetone, lower floor's solvent are trichloromethane, and is as shown in table 1.
Upper strata solvent and lower floor's solvent are 1: 1 by volume.
Earlier lower floor's solvent is added container; Slowly add in the container along wall of container with the speed of 30～60mL/min the upper strata solvent; To prevent to add too fast shortened two kinds of organic reagents time that mixes, left standstill after adding 1～2 minute, two kinds of solvents have tangible layering.The upper strata solvent liquid level is apart from container head 50～100mm.
Table 1 satisfies the solvent matching list of settling condition
| The upper strata solvent | Trichloromethane | Epoxy chloropropane | Acetate | Acetone |
| Lower floor's solvent | Tetracol phenixin | Diazomethane | Tetracol phenixin | Trichloromethane |
(3) extracting and separating
The silicon that obtains after step (1) processing and the mixture micro mist of silit are added from separator column top; The mixture micro mist is constantly sedimentation in two kinds of solvents; After the mixture micro mist all added; Standing sedimentation 10～15 minutes, most of silicon-carbide particle fall in lower floor's solvent, and silicon grain then is in the solvent of upper strata.Open the middle valve of separator column this moment, emits the mixture of upper strata solvent and silicon, adopts the washing method of pumping filtration to reclaim silicon, and separate the upper strata solvent; Open the bottom valve of separator column, emit the mixture of lower floor's solvent and silit, adopt the washing method of pumping filtration to reclaim silit, and reclaim lower floor's solvent.
The washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, and the mixture of above-mentioned upper strata solvent and silicon is carried out suction filtration, obtains filter cake and upper strata solvent, repeats following process 2～5 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Washing suction filtration working method to lower floor's solvent and silit mixture is identical with the washing suction filtration working method of upper strata solvent and silicon mixture; That is: the mixture to above-mentioned lower floor solvent and silit carries out suction filtration; Obtain filter cake and lower floor's solvent, repeat following process 2～5 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(4) reclaim solvent
Step (3) is separated the upper strata solvent reusable edible that obtains; Step (3) is separated the lower floor's solvent that obtains and is contained a spot of upper strata solvent; With lower floor's solvent air distillation, separate upper strata solvent and lower floor's solvent (distillation temperature is the boiling point of low boiling point solvent), recycling.
(5) powder is purified
Filter cake to step (3) washing suction filtration obtains is at last washed suction filtration more respectively, and the washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, repeats following process 2～5 times respectively:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Respectively at 80～100 ℃ of oven dry, the time is 10～15 minutes, obtains silica flour and carborundum powder respectively with the filter cake that obtains at last of washing suction filtration.
Realized the extracting and separating of silicon and silit through above each step, obtaining silica flour and purity that purity is 91%～93% (mass percent) is the above carborundum powder of 86% (mass percent).
The test of its moderate purity is measured through quantitative chemical analysis, removes silicon with the nitration mixture of hydrofluoric acid and nitric acid earlier, waits the quality that obtains silit through filtering washing, records the purity of sample with difference assay.Fig. 3 is the size distribution curve of purification silica flour, and curve shows: particle mainly concentrates on 0.120～15.136 μ m.Wherein the particle of 0.120～0.275 μ m occupies more than 90% whole (volume ratios).
The scanned photograph of silica flour is as shown in Figure 4, from the scanning picture, can see short grained silicon and a small amount of oarse-grained silit.
The silicon-carbide particle that obtains mainly is distributed in 1.2～23.8 mu m ranges, and wherein the particle of granularity 1.2～11.4 μ m occupies more than 85% of TV, and Fig. 5 and Fig. 6 have provided the carborundum powder size distribution curve and the SEM figure of extraction respectively.
The silica flour that obtains obtains purer silica flour (ordinary method) through high temperature founding processing, directional freeze or zone melting.
Silit is handled through existing method, removes wherein silicon etc., recycle like pickling.
The inventive method; Adopt two kinds of solvents that pretreated cutting slurry is carried out the technology of extracting and separating, confirmed the coupling of two kinds of solvents, can make the silicon purity in the refined powder material reach 93% through the extracting and separating enrichment; Pass through founding divided silicon and a spot of silit again; Then silicon is carried out the purification of directional freeze, zone-melting technology completion HIGH-PURITY SILICON, the silit purity of recovery reaches 86%, and can pass through conventional method recycle and reuse.The present invention has following advantage: at first, not only reclaimed HIGH-PURITY SILICON and silit effectively, and in the purification HIGH-PURITY SILICON, can not introduce the deleterious impurity element of HIGH-PURITY SILICON performance.Secondly, simple for process, equipment is ripe, is prone to realize industriallization.The inventive method can solve the shortage of silicon raw material effectively, and the cutting waste material that solves for a long time pollutes the utilization ratio of raising silicon resource.
Description of drawings
Existing silicon single crystal of Fig. 1 and the main recovery process flow sheet of polysilicon cutting slurry;
Fig. 2 is an extracting and separating device synoptic diagram of the present invention;
The silicon particle size distribution curve of Fig. 3 embodiment 1 preparation;
The SEM picture of the silica flour of Fig. 4 embodiment 1 preparation;
The carborundum powder size distribution curve of Fig. 5 embodiment 1 preparation;
The SEM picture of the silit of Fig. 6 embodiment 1 preparation.
Among the figure: 1 middle valve, 2 upper strata solvents, 3 sidewalls, 4 lower floor's solvents, 5 bottom valves are at the bottom of 6.
Embodiment
Below further specify method of the present invention through embodiment, handled raw material is the cutting slurry of Henan solar-grade polysilicon factory, its staple is as shown in table 2.
The raw material staple that table 2 embodiment handles
| Composition | Si | SiC | Fe | Other |
| Content (quality %) | 30.5250 | 34.9966 | 5.9570 | Surplus |
Embodiment 1
Process step by reclaiming silicon and silit in the cutting slurry is following.
(1) slip pre-treatment
Silicon single crystal and polysilicon are cut waste material 300 ℃ of oven dry, and drying time is 25 minutes, mainly removes water and polyoxyethylene glycol in the waste material; Then with mass concentration be 13% hydrochloric acid with oven dry after the cutting powder be 4: 1 mixed by liquid, solid volume ratio; Be mixed with the suspension liquid system; In temperature is stir process 12 hours under 55 ℃, condition of normal pressure; 1500 rev/mins of stir speed (S.S.)s are removed iron and oxide compound thereof in the cutting waste material; The suspension liquid system that obtains is washed suction filtration, further remove iron and other impurity element of free state, obtain the mixture micro mist of silicon and silit.
The washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, earlier the suspension liquid after the stir process under above-mentioned 55 ℃, condition of normal pressure is carried out suction filtration, obtains filter cake, repeats following process 3 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 3 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(2) solvent assembling
Extracting and separating is carried out in separator column, and separator column is for having the end, open glass cylinder (as shown in Figure 2), and its inner bottom surface diameter is 150mm, highly is 2000mm (being D=150mm, H=2000mm).On the separator column sidewall, apart from top 900mm a valve (being H1=900mm) is installed, is middle valve, distance tube end upper limb 30mm place also is equipped with a valve (being H2=30mm) on the separator column sidewall, is the bottom valve.
On physical properties, exist certain difference at the two kinds of material silicon and the silit of cutting in the waste material; The density of silicon is less than the density of silit; And polarity is slightly larger than silit, is prone in polar solvent, reach sedimentation equilibrium according to the big material of polarity, and the material that polarity is little is prone in polar solvent, sink fast; And the little fast principle of material sedimentation that the material sedimentation is slow, density is big of density; Select the solvent of two kinds of opposed polarities and density to carry out extracting and separating, two kinds of solvents are in the upper and lower in the separator column respectively, and the solvent coupling of selection is: the upper strata solvent is that trichloromethane, lower floor's solvent are tetracol phenixin.
Upper strata solvent and lower floor's solvent are 1: 1 by volume.
Earlier lower floor's solvent is added container, the upper strata solvent is slowly added in the container along the speed of wall of container with 45mL/min, to prevent to add too fast shortened two kinds of organic reagents time that mixes, left standstill after adding 1.5 minutes, two kinds of solvents have tangible layering.The upper strata solvent liquid level is apart from container head 70mm.
(3) extracting and separating
The silicon that obtains after step (1) processing and the mixture micro mist of silit are added from separator column top; The mixture micro mist is constantly sedimentation in two kinds of solvents; After the mixture micro mist all added; Standing sedimentation 12 minutes, most of silicon-carbide particle fall in lower floor's solvent, and silicon grain then is in the solvent of upper strata.Open the middle valve of separator column this moment, emits the mixture of upper strata solvent and silicon, adopts the washing method of pumping filtration to reclaim silicon, and separate the upper strata solvent; Open the bottom valve of separator column, emit the mixture of lower floor's solvent and silit, adopt the washing method of pumping filtration to reclaim silit, and reclaim lower floor's solvent.
The washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, and the mixture of above-mentioned upper strata solvent and silicon is carried out suction filtration, obtains filter cake and upper strata solvent, repeats following process 3 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 3 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Washing suction filtration working method to lower floor's solvent and silit mixture is identical with the washing suction filtration working method of upper strata solvent and silicon mixture; That is: the mixture to above-mentioned lower floor solvent and silit carries out suction filtration; Obtain filter cake and lower floor's solvent, repeat following process 3 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 3 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(4) reclaim solvent
Step (3) is separated the upper strata solvent reusable edible that obtains; Step (3) is separated the lower floor's solvent that obtains and is contained a spot of upper strata solvent; With lower floor's solvent air distillation, separate upper strata solvent and lower floor's solvent (distillation temperature is the boiling point of low boiling point solvent), recycling.
(5) powder is purified
Filter cake to step (3) obtains is washed suction filtration more respectively, and the washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, repeats following process 3 times respectively:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 3 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Respectively at 90 ℃ of oven dry, the time is 12 minutes, obtains silica flour and carborundum powder respectively with the filter cake that obtains at last of washing suction filtration.
Realized the extracting and separating of silicon and silit through above each step, obtaining silica flour and purity that purity is 92.8% (mass percent) is the carborundum powder of 86.2% (mass percent).
The test of its moderate purity is measured through quantitative chemical analysis, removes silicon with the nitration mixture of hydrofluoric acid and nitric acid earlier, waits the quality that obtains silit through filtering washing, records the purity of sample with difference assay.Fig. 3 is the size distribution curve of purification silica flour, and curve shows: particle mainly concentrates on 0.120～15.136 μ m.Wherein the particle of 0.120～0.275 μ m occupies more than 90% whole (volume ratios).
The scanned photograph of silica flour is as shown in Figure 4, from the scanning picture, can see short grained silicon and a small amount of oarse-grained silit.
The silicon-carbide particle that obtains mainly is distributed in 1.2～23.8 mu m ranges, and wherein the particle of granularity 1.2～11.4 μ m occupies more than 85% of TV, and Fig. 5 and Fig. 6 have provided the carborundum powder size distribution curve and the SEM figure of extraction respectively.
The silica flour that obtains obtains purer silica flour (3N) through high temperature founding processing, directional freeze or zone melting.
Carborundum powder is realized recycle after handling through ordinary method.
Embodiment 2
Process step by reclaiming silicon and silit in the cutting slurry is following.
(1) slip pre-treatment
Silicon single crystal and polysilicon are cut waste material 320 ℃ of oven dry, and drying time is 20 minutes, mainly removes water and polyoxyethylene glycol in the waste material; Then with mass concentration be 15% hydrochloric acid with oven dry after the cutting powder be 4: 1 mixed by liquid, solid volume ratio; Be mixed with the suspension liquid system; In temperature is stir process 8 hours under 70 ℃, condition of normal pressure; 3000 rev/mins of stir speed (S.S.)s are removed iron and oxide compound thereof in the cutting waste material; The suspension liquid system that obtains is washed suction filtration, further remove iron and other impurity element of free state, obtain the mixture micro mist of silicon and silit.
The washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, earlier the suspension liquid after the stir process under above-mentioned 70 ℃, condition of normal pressure is carried out suction filtration, obtains filter cake, repeats following process 5 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 1 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(2) solvent assembling
Extracting and separating is carried out in separator column, and separator column is for having the end, open glass cylinder (as shown in Figure 2), and its inner bottom surface diameter is 200mm, highly is 2500mm (being D=200mm, H=2500mm).On the separator column sidewall, apart from top 1200mm a valve (being H1=1200mm) is installed, is middle valve, distance tube end upper limb 60mm place also is equipped with a valve (being H2=60mm) on the separator column sidewall, is the bottom valve.
On physical properties, exist certain difference at the two kinds of material silicon and the silit of cutting in the waste material; The density of silicon is less than the density of silit; And polarity is slightly larger than silit, is prone in polar solvent, reach sedimentation equilibrium according to the big material of polarity, and the material that polarity is little is prone in polar solvent, sink fast; And the little fast principle of material sedimentation that the material sedimentation is slow, density is big of density; Select the solvent of two kinds of opposed polarities and density to carry out extracting and separating, two kinds of solvents are in the upper and lower in the separator column respectively, and choosing the upper strata solvent is that epoxy chloropropane, lower floor's solvent are diazomethane.
Upper strata solvent and lower floor's solvent are 1: 1 by volume.
Earlier lower floor's solvent is added container, the upper strata solvent is slowly added in the container along the speed of wall of container with 60mL/min, to prevent to add too fast shortened two kinds of organic reagents time that mixes, left standstill after adding 2 minutes, two kinds of solvents have tangible layering.The upper strata solvent liquid level is apart from container head 100mm.
(3) extracting and separating
The silicon that obtains after step (1) processing and the mixture micro mist of silit are added from separator column top; The mixture micro mist is constantly sedimentation in two kinds of solvents; After the mixture micro mist all added; Standing sedimentation 15 minutes, most of silicon-carbide particle fall in lower floor's solvent, and silicon grain then is in the solvent of upper strata.Open the middle valve of separator column this moment, emits the mixture of upper strata solvent and silicon, adopts the washing method of pumping filtration to reclaim silicon, and separate the upper strata solvent; Open the bottom valve of separator column, emit the mixture of lower floor's solvent and silit, adopt the washing method of pumping filtration to reclaim silit, and reclaim lower floor's solvent.
The washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, and the mixture of above-mentioned upper strata solvent and silicon is carried out suction filtration, obtains filter cake and upper strata solvent, repeats following process 5 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 1 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Washing suction filtration working method to lower floor's solvent and silit mixture is identical with the washing suction filtration working method of upper strata solvent and silicon mixture; That is: the mixture to above-mentioned lower floor solvent and silit carries out suction filtration; Obtain filter cake and lower floor's solvent, repeat following process 5 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 1 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(4) reclaim solvent
Step (3) is separated the upper strata solvent reusable edible that obtains; Step (3) is separated the lower floor's solvent that obtains and is contained a spot of upper strata solvent; With lower floor's solvent air distillation, separate upper strata solvent and lower floor's solvent (distillation temperature is the boiling point of low boiling point solvent), recycling.
(5) powder is purified
Filter cake to step (3) obtains is washed suction filtration more respectively, and the washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, repeats following process 5 times respectively:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 1 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Respectively at 100 ℃ of oven dry, the time is 10 minutes, obtains silica flour and carborundum powder respectively with the filter cake that obtains at last of washing suction filtration.
Realized the extracting and separating of silicon and silit through above each step, obtaining silica flour and purity that purity is 93% (mass percent) is the carborundum powder of 86.5% (mass percent).
The test of its moderate purity is measured through quantitative chemical analysis, removes silicon with the nitration mixture of hydrofluoric acid and nitric acid earlier, waits the quality that obtains silit through filtering washing, records the purity of sample with difference assay.
The silica flour that obtains can be 99.97% (mass percent) through the purity that high temperature founding processing, directional freeze or zone melting obtain silicon ingot.
Carborundum powder is handled through existing method, obtains silit, and content is 98.7% (mass percent).
Embodiment 3
Process step by reclaiming silicon and silit in the cutting slurry is following.
(1) slip pre-treatment
Silicon single crystal and polysilicon are cut waste material 280 ℃ of oven dry, and drying time is 30 minutes, mainly removes water and polyoxyethylene glycol in the waste material; Then with mass concentration be 10% hydrochloric acid with oven dry after the cutting powder be 4: 1 mixed by liquid, solid volume ratio; Be mixed with the suspension liquid system; In temperature is stir process 15 hours under 40 ℃, condition of normal pressure; 300 rev/mins of stir speed (S.S.)s are removed iron and oxide compound thereof in the cutting waste material; The suspension liquid system that obtains is washed suction filtration, further remove iron and other impurity element of free state, obtain the mixture micro mist of silicon and silit.
The washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, earlier the suspension liquid after the stir process under above-mentioned 40 ℃, condition of normal pressure is carried out suction filtration, obtains filter cake, repeats following process 2 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 5 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(2) solvent assembling
Extracting and separating is carried out in separator column, and separator column is for having the end, open glass cylinder (as shown in Figure 2), and its inner bottom surface diameter is 100mmmm, highly is 1500mm (being D=100mm, H=1500mm).On the separator column sidewall, apart from top 600mm a valve (being H1=600mm) is installed, is middle valve, distance tube end upper limb 0mm place also is equipped with a valve (being H2=0mm) on the separator column sidewall, is the bottom valve.
On physical properties, exist certain difference at the two kinds of material silicon and the silit of cutting in the waste material; The density of silicon is less than the density of silit; And polarity is slightly larger than silit, is prone in polar solvent, reach sedimentation equilibrium according to the big material of polarity, and the material that polarity is little is prone in polar solvent, sink fast; And the little fast principle of material sedimentation that the material sedimentation is slow, density is big of density; Select the solvent of two kinds of opposed polarities and density to carry out extracting and separating, two kinds of solvents are in the upper and lower in the separator column respectively, and choosing the upper strata solvent is that acetate, lower floor's solvent are tetracol phenixin.
Upper strata solvent and lower floor's solvent are 1: 1 by volume.
Earlier lower floor's solvent is added container, the upper strata solvent is slowly added in the container along the speed of wall of container with 30mL/min, to prevent to add too fast shortened two kinds of organic reagents time that mixes, left standstill after adding 1 minute, two kinds of solvents have tangible layering.The upper strata solvent liquid level is apart from container head 50mm.
(3) extracting and separating
The silicon that obtains after step (1) processing and the mixture micro mist of silit are added from separator column top; The mixture micro mist is constantly sedimentation in two kinds of solvents; After the mixture micro mist all added; Standing sedimentation 10 minutes, most of silicon-carbide particle fall in lower floor's solvent, and silicon grain then is in the solvent of upper strata.Open the middle valve of separator column this moment, emits the mixture of upper strata solvent and silicon, adopts the washing method of pumping filtration to reclaim silicon, and separate the upper strata solvent; Open the bottom valve of separator column, emit the mixture of lower floor's solvent and silit, adopt the washing method of pumping filtration to reclaim silit, and reclaim lower floor's solvent.
The washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, and the mixture of above-mentioned upper strata solvent and silicon is carried out suction filtration, obtains filter cake and upper strata solvent, repeats following process 2 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 5 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Washing suction filtration working method to lower floor's solvent and silit mixture is identical with the washing suction filtration working method of upper strata solvent and silicon mixture; That is: the mixture to above-mentioned lower floor solvent and silit carries out suction filtration; Obtain filter cake and lower floor's solvent, repeat following process 2 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 5 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(4) reclaim solvent
Step (3) is separated the upper strata solvent reusable edible that obtains; Step (3) is separated the lower floor's solvent that obtains and is contained a spot of upper strata solvent; With lower floor's solvent air distillation, separate upper strata solvent and lower floor's solvent (distillation temperature is the boiling point of low boiling point solvent), recycling.
(5) powder is purified
Filter cake to step (3) obtains is washed suction filtration more respectively, and the washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, repeats following process 2 times respectively:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 5 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Respectively at 80 ℃ of oven dry, the time is 15 minutes, obtains silica flour and carborundum powder respectively with the filter cake that obtains at last of washing suction filtration.
Realized the extracting and separating of silicon and silit through above each step, obtaining silica flour and purity that purity is 92.0% (mass percent) is the carborundum powder of 87.3% (mass percent).
The test of its moderate purity is measured through quantitative chemical analysis, removes silicon with the nitration mixture of hydrofluoric acid and nitric acid earlier, waits the quality that obtains silit through filtering washing, records the purity of sample with difference assay.
The silica flour that obtains can be 99.92% (mass percent) through the purity that high temperature founding processing, directional freeze or zone melting obtain silicon ingot;
Carborundum powder is handled through existing method, obtains silit, and purity is 98.8% (mass percent);
Embodiment 4
Process step by reclaiming silicon and silit in the cutting slurry is following.
(1) slip pre-treatment
Silicon single crystal and polysilicon are cut waste material 300 ℃ of oven dry, and drying time is 30 minutes, mainly removes water and polyoxyethylene glycol in the waste material; Then with mass concentration be 15% hydrochloric acid with oven dry after the cutting powder be 4: 1 mixed by liquid, solid volume ratio; Be mixed with the suspension liquid system; In temperature is stir process 10 hours under 60 ℃, condition of normal pressure; 2000 rev/mins of stir speed (S.S.)s are removed iron and oxide compound thereof in the cutting waste material; The suspension liquid system that obtains is washed suction filtration, further remove iron and other impurity element of free state, obtain the mixture micro mist of silicon and silit.
The washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, earlier the suspension liquid after the stir process under above-mentioned 60 ℃, condition of normal pressure is carried out suction filtration, obtains filter cake, repeats following process 4 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 2 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(2) solvent assembling
Extracting and separating is carried out in separator column, and separator column is for having the end, open glass cylinder (as shown in Figure 2), and its inner bottom surface diameter is 200mm, highly is 2500mm (being D=200mm, H=2500mm).On the separator column sidewall, apart from top 1200mm a valve (being H1=1200mm) is installed, is middle valve, distance tube end upper limb 20mm place also is equipped with a valve (being H2=20mm) on the separator column sidewall, is the bottom valve.
On physical properties, exist certain difference at the two kinds of material silicon and the silit of cutting in the waste material; The density of silicon is less than the density of silit; And polarity is slightly larger than silit, is prone in polar solvent, reach sedimentation equilibrium according to the big material of polarity, and the material that polarity is little is prone in polar solvent, sink fast; And the little fast principle of material sedimentation that the material sedimentation is slow, density is big of density; Select the solvent of two kinds of opposed polarities and density to carry out extracting and separating, two kinds of solvents are in the upper and lower in the separator column respectively, and choosing the upper strata solvent is that acetone, lower floor's solvent are trichloromethane.
Upper strata solvent and lower floor's solvent are 1: 1 by volume.
Earlier lower floor's solvent is added container, the upper strata solvent is slowly added in the container along the speed of wall of container with 40mL/min, to prevent to add too fast shortened two kinds of organic reagents time that mixes, left standstill after adding 2 minutes, two kinds of solvents have tangible layering.The upper strata solvent liquid level is apart from container head 80mm.
(3) extracting and separating
The silicon that obtains after step (1) processing and the mixture micro mist of silit are added from separator column top; The mixture micro mist is constantly sedimentation in two kinds of solvents; After the mixture micro mist all added; Standing sedimentation 15 minutes, most of silicon-carbide particle fall in lower floor's solvent, and silicon grain then is in the solvent of upper strata.Open the middle valve of separator column this moment, emits the mixture of upper strata solvent and silicon, adopts the washing method of pumping filtration to reclaim silicon, and separate the upper strata solvent; Open the bottom valve of separator column, emit the mixture of lower floor's solvent and silit, adopt the washing method of pumping filtration to reclaim silit, and reclaim lower floor's solvent.
The washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, and the mixture of above-mentioned upper strata solvent and silicon is carried out suction filtration, obtains filter cake and upper strata solvent, repeats following process 4 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 2 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Washing suction filtration working method to lower floor's solvent and silit mixture is identical with the washing suction filtration working method of upper strata solvent and silicon mixture; That is: the mixture to above-mentioned lower floor solvent and silit carries out suction filtration; Obtain filter cake and lower floor's solvent, repeat following process 4 times then:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 2 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
(4) reclaim solvent
Step (3) is separated the upper strata solvent reusable edible that obtains; Step (3) is separated the lower floor's solvent that obtains and is contained a spot of upper strata solvent; With lower floor's solvent air distillation, separate upper strata solvent and lower floor's solvent (distillation temperature is the boiling point of low boiling point solvent), recycling.
(5) powder is purified
Filter cake to step (3) obtains is washed suction filtration more respectively, and the washing suction filtration adopts vacuum filtration device commonly used, requires filtering accuracy to reach 0.1 μ m, repeats following process 4 times respectively:
In filter cake, add deionized water, stir, obtain suspension liquid.Count by volume, the amount of the deionized water of adding is 2 times of filter cake amount.This suspension liquid is carried out vacuum filtration, obtain filter cake.
Respectively at 100 ℃ of oven dry, the time is 10 minutes, obtains silica flour and carborundum powder respectively with the filter cake that obtains at last of washing suction filtration.
Realized the extracting and separating of silicon and silit through above each step, obtaining silica flour and purity that purity is 92.6% (mass percent) is the carborundum powder of 87.3% (mass percent).
The test of its moderate purity is measured through quantitative chemical analysis, removes silicon with the nitration mixture of hydrofluoric acid and nitric acid earlier, waits the quality that obtains silit through filtering washing, records the purity of sample with difference assay.
The silica flour that obtains is 99.95% (mass percent) through the content that high temperature founding processing, directional freeze or zone melting obtain silicon ingot.
Carborundum powder is handled through existing method, obtains silit, and content is 98.9% (mass percent).
Claims (8)
1. one kind by the method that reclaims silicon and silit in silicon single crystal and the polysilicon cutting waste material, it is characterized in that process step is following:
(1) slip pre-treatment
With silicon single crystal and the oven dry of polysilicon cutting waste material; Then the cutting powder after hydrochloric acid and the oven dry is mixed; Be mixed with the suspension liquid system; In temperature is stir process 8～15 hours under 40～70 ℃, condition of normal pressure, and the suspension liquid system that obtains is washed suction filtration, obtains the mixture micro mist of silicon and silit;
(2) solvent assembling
Extracting and separating is carried out in separator column, and described separator column is for having the end, open glass cylinder, and its inner bottom surface diameter is 100mm～200mm, highly is 1500～2500mm; On the separator column sidewall, apart from top 600mm～1200mm a valve is installed, is middle valve, distance tube end upper limb 0～60mm place also is equipped with a valve on the separator column sidewall, is the bottom valve; The solvent of selecting is: the upper strata solvent is that trichloromethane, lower floor's solvent are tetracol phenixin; Or the upper strata solvent is that epoxy chloropropane, lower floor's solvent are diazomethane; Or the upper strata solvent is that acetate, lower floor's solvent are tetracol phenixin; Or the upper strata solvent is that acetone, lower floor's solvent are trichloromethane;
Earlier lower floor's solvent is added separator column, the upper strata solvent is slowly added in the separator column along separating post jamb, left standstill after adding 1～2 minute;
(3) extracting and separating
The silicon that obtains after step (1) processing and the mixture micro mist of silit are added from separator column top; After the mixture micro mist all added; Standing sedimentation 10～15 minutes is opened the middle valve of separator column, emits the mixture of upper strata solvent and silicon; Adopt the washing method of pumping filtration to reclaim silicon, and separate the upper strata solvent; Open the bottom valve of separator column, emit the mixture of lower floor's solvent and silit, adopt the washing method of pumping filtration to reclaim silit, and separate lower floor's solvent;
The washing suction filtration adopts the vacuum filtration device, requires filtering accuracy to reach 0.1 μ m, and the mixture of upper strata solvent and silicon is carried out suction filtration, obtains filter cake and upper strata solvent, repeats following process 2～5 times then:
In filter cake, add deionized water, stir, obtain suspension liquid, count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount, and this suspension liquid is carried out vacuum filtration, obtains filter cake;
Mixture to lower floor's solvent and silit carries out suction filtration, obtains filter cake and lower floor's solvent, repeats following process 2～5 times then: in filter cake, add deionized water; Stir; Obtain suspension liquid, count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount; This suspension liquid is carried out vacuum filtration, obtain filter cake;
(4) reclaim solvent
Step (3) is separated the upper strata solvent cycle utilization that obtains; Step (3) is separated the lower floor's solvent that obtains and is contained a spot of upper strata solvent, and step (3) is separated the lower floor's solvent air distillation that obtains, and distillation temperature is the boiling point of low boiling point solvent; Separate upper strata solvent and lower floor's solvent, recycling;
(5) powder is purified
Filter cake to step (3) obtains is washed suction filtration more respectively, and the filter cake that the washing suction filtration obtains is at last dried respectively, obtains silica flour and carborundum powder respectively.
2. it is characterized in that by the method that reclaims silicon and silit in silicon single crystal and the polysilicon cutting waste material bake out temperature is 280～320 ℃ in the step (1) according to claim 1 is described, drying time is 20～30 minutes.
3. described by the method that reclaims silicon and silit in silicon single crystal and the polysilicon cutting waste material according to claim 1, it is characterized in that the hydrochloric acid mass concentration is 10%～15% in the step (1); Cutting powder after hydrochloric acid and the oven dry is mixing in 4: 1 by liquid, solid volume ratio.
4. described by the method that reclaims silicon and silit in silicon single crystal and the polysilicon cutting waste material according to claim 1; It is characterized in that the washing suction filtration adopts the vacuum filtration device in the step (1); Require filtering accuracy to reach 0.1 μ m; Earlier the suspension liquid after the stir process is carried out suction filtration, obtains filter cake, repeat following process 2～5 times then:
In filter cake, add deionized water, stir, obtain suspension liquid; Count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount, and this suspension liquid is carried out vacuum filtration, obtains filter cake.
5. described by the method that reclaims silicon and silit in silicon single crystal and the polysilicon cutting waste material according to claim 1, it is characterized in that solvent and lower floor's solvent volume ratio are 1: 1 to step (2) at the middle and upper levels; The upper strata solvent liquid level is 50～100mm apart from the separator column top.
6. it is characterized in that in the step (2) by the method that reclaims silicon and silit in silicon single crystal and the polysilicon cutting waste material according to claim 1 is described, the upper strata solvent is slowly added in the separator column along separating the speed of post jamb with 30～60mL/min.
7. described by the method that reclaims silicon and silit in silicon single crystal and the polysilicon cutting waste material according to claim 1; It is characterized in that in the step (5); The washing suction filtration adopts the vacuum filtration device, requires filtering accuracy to reach 0.1 μ m, repeats following process 2～5 times respectively:
In filter cake, add deionized water, stir, obtain suspension liquid, count by volume, the amount of the deionized water of adding is 1～5 times of filter cake amount, and this suspension liquid is carried out vacuum filtration, obtains filter cake.
8. it is characterized in that by the method that reclaims silicon and silit in silicon single crystal and the polysilicon cutting waste material in the step (5), bake out temperature is 80～100 ℃ according to claim 1 is described, the time is 10～15 minutes.
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| CN109592886A (en) * | 2017-09-30 | 2019-04-09 | 天津大学 | The method for preparing foam glass based on crystalline silicon cutting waste material |
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| WO2004098848A1 (en) * | 2003-04-23 | 2004-11-18 | Sintef | Method for cleaning sic particles |
| CN101113029A (en) * | 2006-07-26 | 2008-01-30 | 金柏林 | Treatment recovery method for monocrystalline silicon cutting waste liquor |
| CN101513753A (en) * | 2009-03-24 | 2009-08-26 | 河南醒狮高新技术股份有限公司 | Method for recovering waste slurry of multiline cut silicon chips |
| CN101671022A (en) * | 2009-09-28 | 2010-03-17 | 东北大学 | Method for recovering solar-grade polysilicon from single crystal silicon/polysilicon cutting slurry |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004098848A1 (en) * | 2003-04-23 | 2004-11-18 | Sintef | Method for cleaning sic particles |
| CN101113029A (en) * | 2006-07-26 | 2008-01-30 | 金柏林 | Treatment recovery method for monocrystalline silicon cutting waste liquor |
| CN101513753A (en) * | 2009-03-24 | 2009-08-26 | 河南醒狮高新技术股份有限公司 | Method for recovering waste slurry of multiline cut silicon chips |
| CN101671022A (en) * | 2009-09-28 | 2010-03-17 | 东北大学 | Method for recovering solar-grade polysilicon from single crystal silicon/polysilicon cutting slurry |
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