CN103261095A - Method and apparatus for producing silicon - Google Patents

Method and apparatus for producing silicon Download PDF

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Publication number
CN103261095A
CN103261095A CN2011800616056A CN201180061605A CN103261095A CN 103261095 A CN103261095 A CN 103261095A CN 2011800616056 A CN2011800616056 A CN 2011800616056A CN 201180061605 A CN201180061605 A CN 201180061605A CN 103261095 A CN103261095 A CN 103261095A
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China
Prior art keywords
crucible
alloy
ionogen
electrolysis
silicon
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CN2011800616056A
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Chinese (zh)
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刘培生
刘理璋
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YINGBAO DEVELOPMENT Co Ltd
Epro Development Ltd
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YINGBAO DEVELOPMENT Co Ltd
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Priority claimed from PCT/CN2010/002087 external-priority patent/WO2012083480A1/en
Application filed by YINGBAO DEVELOPMENT Co Ltd filed Critical YINGBAO DEVELOPMENT Co Ltd
Priority to CN2011800616056A priority Critical patent/CN103261095A/en
Publication of CN103261095A publication Critical patent/CN103261095A/en
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Abstract

An apparatus for producing pure silicon from an electrolyte includes a first crucible for receiving the electrolyte, a heat source for heating the electrolyte in the first crucible to form a molten electrolyte, an anode and a cathode which are adapted for electrical/ionic communication with the molten electrolyte wherein electrolysis is able to be applied to the molten electrolyte when a potential difference is provide between the anode and the cathode. A stirring device is adapted for stirring the molten electrolyte when electrolysis is being applied, whereby pure silicon is produced which is soluble with the anode to form an alloy.

Description

Method and apparatus for the manufacture of silicon
Technical field
The present invention relates to for the manufacture of silicon and especially have the method and apparatus of the silicon of the purity that solar cell application of being applicable to etc. uses.
Background technology
Have recognized that solar battery technology is the environment amenable alternative approach that conventional energy produces form (producing form as the energy that uses fossil oil).Therefore, solar battery technology has represented great commercial market.
At present, think that extensively the technology of being researched and developed by Siemens Company (Siemens) (" Siemens Method (Siemens Process) ") is the leading method for the manufacture of the silicon of the purity with the solar cell application of being applicable to.In Siemens Method, make the high purity silicon rod under 1150 ℃, be exposed to trichlorosilane make trichlorosilane gas decompose and at the extra silicon of silicon rod deposition to increase silicon rod.But, think the relatively costly and environmental friendliness not of Siemens Method.Aspect energy, estimate that 1 ton of solar battery grade silicon of the every generation of Siemens Method just consumes about 200 megawatts. hour.
Also researched and developed the alternative approach of carbothermic method as Siemens Method.But these methods can not produce the silicon with solar battery grade quality, because can't remove intrinsic impurities in the carbon (as boron and phosphorus) it are reached suitably than low degree (namely reaching the content of PPM or parts per billion (ppb)).
Therefore, notice the alternatives that needs to manage to solve the above-mentioned problem relevant with manufacturing solar battery grade silicon.
Summary of the invention
The present invention manages to alleviate at least a the problems referred to above.
The present invention may relate to some kinds of broad form.The embodiment of the invention can comprise a kind of or its any combination in the different broad form described herein.
In first broad form, the invention provides a kind of method from ionogen manufacturing pure silicon, wherein said method may further comprise the steps:
(i) in first crucible, heat ionogen to form fused electrolyte; With
(ii) by providing potential difference that electrolysis is applied to fused electrolyte between anode and negative electrode, described anode and negative electrode are suitable for and fused electrolyte electricity/ionic connection;
Thereby wherein stir fused electrolyte and produce pure silicon when just applying electrolysis, it can dissolve the formation alloy with anode.
Advantageously, stirring fused electrolyte during electrolysis can help to produce ionic current in the fused electrolyte and increase contacting between ionogen and the molten alloy anode.Then can use as the isolation technique of hereinafter further discussing and from alloy, easily separate pure silicon.
Ionogen preferably can comprise sodium aluminum fluoride, calcium oxide particle and quartzy particle.In electrolyte weight, ionogen more preferably can comprise about 82% to 94% sodium aluminum fluoride particle.In electrolyte weight, ionogen also can comprise about 3% to 15% calcium oxide particle usually.In electrolyte weight, ionogen also can preferably comprise about 3% quartzy particle.In electrolyte weight, ionogen more preferably can comprise about 87% sodium aluminum fluoride particle, 10% calcium oxide particle and 3% quartzy particle.The quartzy particle of controlled interpolation keeps in fact in ionogen in electrolyte weight about 3% quartzy particle in the fused electrolyte thereby the present invention also preferably can be included in during the electrolysis.
Usually, first crucible can comprise at least a in carbon, nitric acid silicon and the carbofrax material.When first crucible material preferably may be suitable in being placed in induction furnace heating or in being placed in direct heat oven the time with relatively efficient manner heat conduction.First crucible preferably includes by inside peripheral wall with for the recess that receives electrolytical bottom portion defining.Usually, recess can comprise cylinder form.
First crucible lining preferably can be arranged in the first crucible recess between first crucible and the ionogen.The profile of first crucible lining more selects excellently can be complementary in fact with the inside peripheral wall of first crucible.First crucible lining preferably can comprise quartz material.Perhaps, first crucible lining can comprise at least a in calcium oxide, magnesium fluoride, Sodium Fluoride and the silicon materials.Preferably heat-resisting under at least about the temperature more than 1000 ℃ as the material of first crucible lining.Corrosion-resistant when also preferably during electrolytic process, being exposed to ionogen as the material of first crucible lining.Advantageously, first crucible lining can help to prevent that ionogen is inhaled in first sidewall of crucible, and ionogen is inhaled into first sidewall of crucible and is easy to cause that the efficient of the electrolytic process that produces alloy anode reduces.In addition, be inhaled in first sidewall of crucible because first crucible lining helps to block ionogen, this helps to prevent short circuit, and short circuit will have a strong impact on the efficient that makes the silicon electrolysis produce alloy anode.
Perhaps, can first crucible lining be formed by fused electrolyte itself by in fused electrolyte, producing thermograde, a part of fused electrolyte of the inside peripheral wall of contiguous first crucible is solidified.Usually, can use electric-arc heating between the fused electrolyte of negative electrode and the contiguous first crucible inside peripheral wall, to produce thermograde.
Usually, can use at least a heating ionogen in electric arc furnace and the induction furnace.
Usually, can use magnetic to stir the induction furnace of fused electrolyte and at least a stirring fused electrolyte in the mechanical stirrer.
Usually, anode can comprise at least a in copper, gold and silver, zinc and the magnesium material.Anode preferably includes copper product.Anode more preferably comprises the alloy of copper and pure silicon.Usually, pure silicon can account for about 3 weight % of alloy.
In the step (i) of first broad form before, preferably alloy contiguous first crucible bottom in first crucible is settled and made its fusion in first crucible, thereby can make described ionogen in first crucible, be deposited on the molten alloy top subsequently in order to prepare for the step (i) of first broad form that will carry out.Usually, alloy can fusion under the temperature between about 950 ℃ to 980 ℃.
Usually, the step of first broad form (i) can be included in first crucible ionogen is heated at least about 900 ℃ of temperature to form fused electrolyte.
During the step of first broad form (ii), thereby preferably fused electrolyte is remained under a certain temperature fused electrolyte is not solidified.Usually, temperature can be maintained at about between 900 ℃ to 1000 ℃ to alleviate the curing of fused electrolyte.Preferably keep temperature be about 980 ℃ to prevent that fused electrolyte from solidifying.
Usually, when applying electrolysis, can make fused electrolyte in first crucible, be exposed to current density between about 0.1 ampere/square centimeter to 2.0 amperes/square centimeter.
Usually, negative electrode can comprise at least a in carbon, copper and the platinum material.Preferably can form negative electrode by the purifying carbon dust is compressed into solid bar.More preferably can wash to remove impurity and come the purifying carbon dust by making carbon dust be exposed to pickling and chlorine.
Preferably after ionogen has been heated the formation fused electrolyte, negative electrode is placed in first crucible, wherein negative electrode and fused electrolyte electricity/ionic connection.
The present invention preferably can be included in the (ii) step of back separation pure silicon from alloy of step.Usually, the step that can when electrolytic pure silicon no longer can dissolve with alloy, carry out from alloy, separating pure silicon.If the temperature of alloy is between about 950 ℃ to 980 ℃ usually again, then when the pure silicon in the alloy accounted for 25 weight % of alloy, pure silicon may no longer can dissolve with alloy.
Usually, the step of separating pure silicon from alloy can comprise temperature regulation with alloy between about 800 ℃ to 850 ℃, thereby pure silicon can be separated from alloy natively.Before the temperature regulation with alloy arrives between about 800 ℃ to 850 ℃, also can preferably alloy be transferred in second crucible.Second crucible preferably can comprise the material that alloy and/or melting salt is inertia.Usually, melting salt can be used for covering the pure silicon of separation to alleviate reoxidizing of pure silicon.Usually, in weight alloy, when from alloy, isolating the pure silicon particle of predetermined percentage, the alloy in second crucible can be drawn again and get back in first crucible.More generally, when the alloy in second crucible being drawn again when getting back in first crucible, can comprise about 11% pure silicon particle in weight alloy in the pure silicon particle of the predetermined percentage of weight alloy.
Perhaps and/or in addition, get back in first crucible for replacing when in second crucible, from alloy, isolating the pure silicon particle of predetermined percentage the alloy in second crucible drawn again, can apply following steps:
(i) make alloy in second crucible form at least a in band and the powder; With
(ii) band or powder are applied re-electrolysis;
Thereby can from alloy, isolate the pure silicon particle that is nano-scale pure silicon particulate forms.
Usually, can be by at least a formation band in casting and the extruded alloy.Usually also can or grind alloy by mechanical disruption and form powder.Preferably form powder by the alloy of in controlled environment, milling.Usually, powder can comprise that micron is to the nano-scale alloy particle.
The step that applies re-electrolysis preferably can comprise band or powder are immersed in the electrolyte solution.Usually, electrolyte solution can comprise spirit of salt (HCl), dehydration acetic acid, iodine solution (being liquor kalii iodide (potassium iodine solution)), hydrazoic acid (HN 3), at least a and its combination in the acetone, dense ethanol.During re-electrolysis, the acidity of electrolyte supplement solution preferably.
Usually, can during re-electrolysis, apply electric current less than 1 ampere.
After carrying out re-electrolysis, preferably can further process the electrolyte solution that contains nano-scale pure silicon particle to separate nano-scale pure silicon particle and electrolyte solution.Usually, can separate nano-scale pure silicon particle and electrolyte solution by centrifugation.Preferably the nano-scale pure silicon particle that separates can be stored in subsequently again and be applicable in the material that alleviates with the free oxygen reaction.Common described material can comprise dense ethanol or dewatered ethanol.
Perhaps, it will be understood by one of ordinary skill in the art that and the alloy in first crucible is directly carried out any step in the above-mentioned step of separating pure silicon in second crucible from alloy under can the situation in not moving on to second crucible.
Perhaps, the step of first broad form of the present invention (ii) after, the step of separating pure silicon in the alloy that produces in first crucible can comprise carries out re-electrolysis to alloy, thereby puts upside down the polarity of anode and negative electrode.Preferably, by putting upside down polarity, anode can provide positive node and negative electrode that negative nodal point can be provided during re-electrolysis.Usually, re-electrolysis can produce to be deposited on and contain silicon and electrolytical mixture on the anode.Usually, be formed at the silicon that mixture on the anode can comprise about 300 mesh size of particles.
Preferably the alloy from the crucible that first crucible separates is carried out re-electrolysis, the described crucible that separates with first crucible can comprise the SiC material usually.
Usually, can use at least a in the following electrolyte composition to carry out re-electrolysis (approximate weight per-cent):
（i）10%K 2SiF 6、25%AlF 3、25%NaF、35%BaF 2、5%CaF 2；
(ii) 40%-70%Na 3AlF 6, 5%-20%K 2SiF 6, 5%-15%CaF 2, 5%-10%CaO; With
（iii）95%-99%Na 3AlF 6、1%-5%SiO 2。
The mixture that is deposited on the anode preferably can be at least about 1450 ℃ or be higher than fusion under 1450 ℃ the temperature, thus make silicon can be in ionogen after the cooling coalescent in flakes or ingot.Usually can use induction furnace etc. to make the mixture fusion.
Usually, a cooling can use strainer (as screen cloth etc.) to filter coalescent silicon chip or ingot from ionogen.Perhaps, can make mixture fusion bout gold and make by the controllable rate cooling and to float to the top to collect on the silicon.Usually, can make mixture with Figure 19 in phasor in fusion bout gold under the appointment melt temperature consistent temperature described.In second broad form, the invention provides a kind ofly for the device of making pure silicon from ionogen, it comprises:
First crucible, it is used for receiving ionogen;
Thermal source, its ionogen that is used for heating first crucible is to form fused electrolyte;
Anode and negative electrode, it is suitable for and fused electrolyte electricity/ionic connection, and wherein when providing potential difference between anode and negative electrode, electrolysis can be applied to fused electrolyte; With
Agitation means produces pure silicon thereby be used for stirring fused electrolyte when just applying electrolysis, and described pure silicon can dissolve the formation alloy with anode.
Ionogen preferably can comprise sodium aluminum fluoride, calcium oxide particle and quartzy particle.In electrolyte weight, ionogen more preferably can comprise about 82% to 94% sodium aluminum fluoride particle.In electrolyte weight, ionogen also can comprise about 3% to 15% calcium oxide particle usually.In electrolyte weight, ionogen also preferably can comprise about 3% quartzy particle.In electrolyte weight, ionogen more preferably can comprise about 87% sodium aluminum fluoride particle, 10% calcium oxide particle and 3% quartzy particle.
The present invention preferably can comprise divider, thereby it is used for keeping in fact in ionogen in electrolyte weight about 3% quartzy particle during the electrolysis quartzy particle being assigned to ionogen.
Usually, first crucible can comprise at least a in carbon, nitric acid silicon and the carbofrax material.First crucible preferably can comprise by inside peripheral wall with for the recess that receives electrolytical bottom portion defining.Usually, recess can comprise cylindrical or rectangular shape.
The present invention preferably can comprise first crucible lining in the first crucible recess that is arranged between first crucible and the ionogen.The profile of first crucible lining selects again excellently can be complementary in fact with the inside peripheral wall of first crucible.Usually, first crucible lining can comprise at least a in quartz, calcium oxide, magnesium fluoride, Sodium Fluoride and the silicon materials.
Perhaps, first crucible can comprise first crucible lining that is solidified to form of a part of fused electrolyte that is caused by the thermograde that produces in the fused electrolyte.Usually, the present invention can comprise the electric-arc heating device, and it is for generation of the thermograde between the fused electrolyte of negative electrode and the contiguous first crucible inside peripheral wall.
Usually, thermal source can comprise at least a in electric arc furnace and the induction furnace.Preferred electric arc furnace can be main thermal source.
Usually, can use magnetic to stir the induction furnace of fused electrolyte and at least a stirring fused electrolyte in the mechanical stirrer.Advantageously, induction furnace can reduce production cost by the dual-use function that is provided as thermal source and agitation means.
Usually, anode can comprise at least a in copper, silver, gold, zinc and the magnesium material.Anode preferably can comprise copper product.Anode more preferably can comprise the alloy of copper and pure silicon.Usually, pure silicon can account for about 3 weight % of alloy to 7 weight %.
Preferably, alloy can be close to the first crucible bottom fusion and ionogen can be placed in the alloy top in first crucible.Usually, thermal source may be suitable for making alloy fusion under the temperature between about 950 ℃ to 980 ℃.
Usually, thermal source may be suitable for the ionogen in first crucible is heated at least about 900 ℃ temperature in order to form fused electrolyte.
Preferably, during the fused electrolyte electrolysis, thereby thermal source may be suitable for fused electrolyte remained under a certain temperature fused electrolyte is not solidified.Usually, thermal source may be suitable for keeping fused electrolyte temperature between about 900 ℃ to 1000 ℃ to prevent that fused electrolyte from solidifying.Preferably, thermal source may be suitable for keeping the temperature of fused electrolyte be about 980 ℃ to prevent that fused electrolyte from solidifying.
Usually, when applying electrolysis, can make fused electrolyte in first crucible, be exposed to current density between about 0.1 ampere/square centimeter to 2.0 amperes/square centimeter.
Usually, negative electrode can comprise at least a in carbon, copper and the platinum material.Negative electrode preferably can comprise the solid bar that forms by compression purifying carbon dust.More preferably, wash to remove impurity and come the purifying carbon dust by making carbon dust be exposed to pickling and chlorine.Negative electrode also is placed in first crucible preferably suitable for be heated the formation fused electrolyte at ionogen after, thereby makes negative electrode and fused electrolyte electricity/ionic connection.
The present invention preferably can comprise a kind of for the device that separates pure silicon from alloy.Preferably, be used for to be suitable for when electrolytic pure silicon no longer can dissolve with alloy, from alloy, separating pure silicon from the device of alloy separation pure silicon.Again normally, if the temperature of alloy between about 950 ℃ to 980 ℃, then when the pure silicon in the alloy accounted for the about 25 weight % of alloy, pure silicon may no longer can dissolve with alloy.
Usually, be used for to be suitable for temperature regulation with alloy to about 800 ℃ to 850 ℃ from the device that alloy separates pure silicon, thereby can from alloy, separate pure silicon.Also preferably, be used for to be suitable for the temperature regulation of alloy is being transferred to alloy second crucible before to about 800 ℃ to 850 ℃ from the device that alloy separates pure silicon.Also preferably, second crucible can comprise the material that alloy and/or melting salt is inertia.Melting salt preferably can be used for covering the pure silicon of separation to alleviate reoxidizing of pure silicon.Usually, the present invention may be suitable for when the pure silicon particle of isolating from alloy in the predetermined percentage of weight alloy the alloy in second crucible being introduced in first crucible again.More generally, can comprise about 11% pure silicon particle in weight alloy in the pure silicon particle of the predetermined percentage of weight alloy.
Perhaps and/or in addition, the alloy that is used for second crucible device that separates pure silicon can comprise:
(i) be used for making the alloy formation band of second crucible and at least a device in the powder; With
(ii) be used for band or powder are applied the device of re-electrolysis;
Thereby can from alloy, isolate the pure silicon particle that is nano-scale pure silicon particulate forms.
Usually, the device that is used for making alloy form band may be suitable for alloy casting or be squeezed into band.Also normally, the device that is used to form powder may be suitable in controlled environment alloy mechanical disruption or grind into powder.Preferably, can form powder by the alloy of milling.Usually, powder can comprise that micron is to the nano-scale alloy particle.
Preferably may be suitable for band or powder are immersed in electrolyte solution for the device that applies re-electrolysis.Usually, electrolyte solution can comprise spirit of salt (HCl), dehydration acetic acid, iodine solution (being liquor kalii iodide), hydrazoic acid (HN 3), at least a and its combination in the acetone, dense ethanol.Preferably, during re-electrolysis, the acidity of electrolyte solution can be added.
Usually, the device that is used for applying re-electrolysis may be suitable for applying the electric current less than 1 ampere during re-electrolysis.
The present invention preferably can comprise the device for the nano-scale pure silicon particle from electrolyte solution separate electrolyte solution after applying re-electrolysis.Usually, this device can comprise centrifugal device, and it is used for from electrolyte solution centrifugation nano-scale pure silicon particle.The present invention also preferably can comprise storing unit, and its nano-scale pure silicon particle that is used for separating is stored in and is applicable to the material that alleviates with the reaction of free oxygen.Usually, described material can comprise dense ethanol.
Perhaps, it will be understood by one of ordinary skill in the art that for the device that from alloy, separates pure silicon at second crucible and can be suitable for directly in first crucible, from alloy, separating pure silicon under the situation in not moving on to second crucible similarly.
Perhaps, the device that is used for separating in the alloy that first crucible produces pure silicon is suitable for alloy is carried out re-electrolysis, thereby the polarity of anode and negative electrode is put upside down during re-electrolysis.Preferably, by putting upside down polarity, anode can provide positive node and negative electrode that negative nodal point can be provided.Usually, re-electrolysis can produce to be deposited on and contain silicon and electrolytical solid composite on the anode.Usually, the silicon that is formed in the mixture on the anode can have about 300 mesh size of particles.
Preferably, be used for to comprise the crucible that separates with first crucible from the device of alloy separation pure silicon, can in the described crucible that separates, under the situation of anode and negative electrode polarity reversal, carry out re-electrolysis to alloy.Usually, the crucible that separates can comprise the SiC material.
Usually, can be configured for use in for separating of the device of pure silicon and use at least a in the following ionogen to carry out re-electrolysis (approximate weight per-cent):
（i）10%K 2SiF 6、25%AlF 3、25%NaF、35%BaF 2、5%CaF 2；
(ii) 40%-70%Na 3AlF 6, 5%-20%K 2SiF 6, 5%-15%CaF 2, 5%-10%CaO; With
（iii）95%-99%Na 3AlF 6、1%-5%SiO 2。
Preferably, device can comprise heating arrangements, and it is suitable for making the mixture that is deposited on the anode at least about 1450 ℃ or be higher than fusion under 1450 ℃ the temperature, thus make silicon one cooling namely in ionogen coalescent in flakes or ingot.Usually, be used for making the heating arrangements of mixture fusion can comprise induction furnace etc.
Preferably, device can comprise the strainer as mesh gauze filter, and it is suitable for filtering coalescent silicon chip or ingot from ionogen when cooling.
Perhaps, device can comprise be used to make mixture fusion bout gold and by the mechanism of the cooling combined thing of controllable rate so that float to the top on the silicon and collect being used for.Usually, with Figure 19 in phasor under the appointment melt temperature consistent temperature described with mixture fusion bout gold.
In the 3rd broad form, the invention provides a kind of method from ionogen manufacturing pure silicon, wherein said method may further comprise the steps:
(i) in first crucible, heat ionogen to form fused electrolyte; With
(ii) by providing potential difference that fused electrolyte is applied electrolysis between anode and negative electrode, described anode and negative electrode are suitable for and fused electrolyte electricity/ionic connection;
Wherein first crucible lining is arranged in and makes in first crucible that thereby fused electrolyte separates the generation pure silicon in fact with the inside peripheral wall of first crucible when just applying electrolysis, and described pure silicon can dissolve the formation alloy with anode.
In the 4th broad form, the invention provides a kind ofly for the device of making pure silicon from ionogen, it comprises:
First crucible, it is used for receiving ionogen;
Thermal source, its ionogen that is used for heating first crucible is to form fused electrolyte;
Anode and negative electrode, it is suitable for and fused electrolyte electricity/ionic connection, and wherein when providing potential difference between anode and negative electrode, electrolysis can be applied to fused electrolyte; With
First crucible lining, it is arranged in and makes in first crucible that fused electrolyte separates in fact with the inside peripheral wall of first crucible when just applying electrolysis to fused electrolyte;
Wherein produce and to dissolve the pure silicon that forms alloy with anode.
In the 5th broad form, the invention provides and a kind ofly become the method for separating pure silicon at least a alloy copper, gold and silver, zinc and the magnesium material of alloy from containing with the pure silicon particle, said method comprising the steps of:
(i) make alloy form at least a in band and the powder; With
(ii) band or powder are applied electrolysis;
Thereby can from alloy, isolate the pure silicon particle that is nano-scale pure silicon particulate forms.
Usually, can be by at least a formation in casting and the extruded alloy.Usually powder can form by mechanical disruption in controlled environment or grinding alloy.Preferably, powder forms by the alloy of milling.Usually, powder can comprise that micron is to the nano-scale alloy particle.
Preferably, the step of carrying out electrolysis can comprise band or powder are immersed in the electrolyte solution.Usually, electrolyte solution can comprise spirit of salt (HCl), dehydration acetic acid, iodine solution (being liquor kalii iodide), hydrazoic acid (HN 3), at least a and its combination in the acetone, dense ethanol.Preferably, during electrolysis, the acidity of electrolyte solution can be added.
Usually, can during electrolysis, apply electric current less than 1 ampere.
Preferably, after carrying out electrolysis, the electrolyte solution that contains nano-scale pure silicon particle can further process to separate nano-scale pure silicon particle and electrolyte solution.Usually, can separate nano-scale pure silicon particle and electrolyte solution by centrifugation.Also preferably, the nano-scale pure silicon particle that separates is stored in is applicable in the material that alleviates with the free oxygen reaction subsequently.Usually, described material can comprise dense ethanol.
In the 6th broad form, the invention provides a kind ofly for becoming the device that separates pure silicon at least a alloy of copper, gold and silver, zinc and magnesium material of alloy from containing with the pure silicon particle, described device comprises:
(i) be used for making alloy to form at least a device of band and powder; With
(ii) be used for band or powder are applied the device of electrolysis;
Thereby can from alloy, isolate the pure silicon particle that is nano-scale pure silicon particulate forms.
Usually, the device that is used for making alloy form band may be suitable for alloy casting or be squeezed into band.The device that is used to form powder also may be suitable for alloy mechanical disruption or grind into powder usually.Preferably can form powder by the alloy of in controlled environment, milling.Usually, powder can comprise that micron is to the nano-scale alloy particle.
Preferably, may be suitable for band or powder are immersed in electrolyte solution for the device that carries out electrolysis.Usually, electrolyte solution can comprise spirit of salt (HCl), dehydration acetic acid, iodine solution (being liquor kalii iodide), hydrazoic acid (HN 3), at least a and its combination in the acetone, dense ethanol.Preferably, during electrolysis, the acidity of solution can be added.
Usually, the device that is used for carrying out electrolysis may be suitable for applying the electric current less than 1 ampere during electrolysis.
Preferably, the present invention can comprise the device for the nano-scale pure silicon particle from electrolyte solution separate electrolyte solution.Usually, this device can comprise centrifugal device, and it is used for from electrolyte solution centrifugation nano-scale pure silicon particle.The present invention also preferably can comprise storing unit, and its nano-scale pure silicon particle that is used for separating is stored in and is applicable to the material that alleviates with the reaction of free oxygen.Usually, described material can comprise dense ethanol.
In any aforementioned broad form of the present invention, second crucible lining can be arranged in first crucible between alloy and first crucible lining.Usually, second crucible lining can comprise at least a to prolong the work-ing life of first liner, because SiC and SiN are wear-resisting in SiN or the SiC material.Preferably, second crucible lining can comprise the surface of atresia in fact.
Usually, second crucible lining can be immersed under the first crucible interalloy (when the fusion) highest level in fact and in first crucible, keep during the electrolysis being immersed in fact under the alloy highest level being inhaled in second crucible lining to alleviate ionogen.
In the 7th broad form, the invention provides a kind of method of making pure silicon, said method comprising the steps of:
(i) in crucible, make the ionogen that contains quartz carry out electrolysis, wherein form and contain silicon and electrolytical solid composite;
(ii) follow, make the mixture fusion, wherein the silicon particle in the mixture is coalescent in ionogen when cooling;
(iii) follow, when the temperature of fusion mixture is lower than about 1414 ℃, from ionogen, leach coalescent silicon.
Usually, in step (i), ionogen can comprise the combination of quartz plate/piece and Powdered quartz.Preferably, the step (i) of carrying out electrolysis during being included in electrolysis is periodically added in the crucible Powdered quartz to keep supply silicon particle to.
Usually, formed mixture can comprise about 20 weight % silicon particles and about 80 weight % ionogen particles.
Preferably, use 2 raw-material carbon nodes with an amount of carried out electrolytic process to carry out electrolysis.
In the 8th broad form, the invention provides a kind of device for the manufacture of pure silicon, it comprises:
(i) crucible wherein is suitable for receiving the ionogen that contains quartz;
(ii) electrolytic system, it is suitable for the ionogen in the crucible is carried out electrolysis, and wherein silicon and electrolytical solid composite are deposited in the crucible;
(iii) heating arrangements, it is suitable for making the mixture fusion, and wherein the silicon particle in the mixture is coalescent in ionogen when cooling; With
(iv) strainer, it is suitable for leaching coalescent silicon from ionogen when the temperature of fusion mixture is lower than about 1414 ℃.
Usually, ionogen can comprise the combination of quartz plate/piece and Powdered quartz.Preferably, present invention resides in during the electrolysis Powdered quartzy periodically being delivered in the crucible during electrolysis, to keep the mechanism of supply silicon particle.
Usually, the mixture that forms by the ionogen electrolysis can comprise about 20 weight % silicon particles and about 80 weight % ionogen particles.
Electrolytic system preferably includes 2 raw-material carbon nodes with an amount of carried out electrolytic process.
In the general form in Kowloon-Kwangtung, the invention provides a kind of pure silicon of making according to any broad form of the present invention described herein.
In the tenth broad form, the invention provides a kind of solar cell, it comprises the pure silicon of making according to any broad form of the present invention described herein.
In the 11 broad form, the invention provides a kind of battery, it comprises the pure silicon of making according to any broad form of the present invention described herein.Usually, the anode of battery is to be formed by pure silicon.
In the 12 broad form, the invention provides a kind of crucible lining that is applicable to any broad form of the present invention described herein.In the 13 broad form, the invention provides a kind of electrical grade silicon materials that form integrated circuit component that are applicable to, described electrical grade silicon materials are according to any broad form manufacturing of the present invention described herein.
Description of drawings
By describe below in conjunction with accompanying drawing of the present invention preferred but the detailed description of non-limiting example is more fully understood the present invention, wherein:
Fig. 1 shows the schema of making the method for pure silicon according to the embodiment of the invention from ionogen;
Fig. 2 shows that the alloy that is used for from the method steps of describing according to Fig. 1 forms separates the schema of the embodiment method of pure silicon;
Fig. 3 shows the sectional view for the manufacture of the device of pure silicon according to the embodiment of the invention;
Fig. 4 (a) and Fig. 4 (b) are illustrated in first crucible behind the once electrolytic EDX figure and the corresponding SEM image of first sample that obtains from the alloy that contains pure silicon;
Fig. 5 (a) and Fig. 5 (b) are illustrated in first crucible behind the once electrolytic EDX figure and the corresponding SEM image of second sample that obtains from the alloy that contains pure silicon;
Fig. 6 (a) and Fig. 6 (b) are illustrated in first crucible behind the once electrolytic EDX figure and the corresponding SEM image of the 3rd sample that obtains from the alloy that contains pure silicon;
Fig. 7 (a) and Fig. 7 (b) are illustrated in first crucible behind the once electrolytic EDX figure and the corresponding SEM image of the 4th sample that obtains from the alloy that contains pure silicon;
Fig. 8 shows EDX data and the corresponding SEM image of pure silicon sample, and described pure silicon sample is transferred to natural separation the alloy of second crucible according to the embodiment of the invention from first crucible;
Fig. 9 shows EDX data and the corresponding SEM image of nano-scale pure silicon sample, and described nano-scale pure silicon sample separates according to embodiment of the invention alloy from second crucible during relating to the re-electrolysis of using 10% spirit of salt (HCl) electrolyte solution;
Figure 10 shows EDX data and the corresponding SEM image of nano-scale pure silicon sample, and described nano-scale pure silicon sample separates according to embodiment of the invention alloy from second crucible during relating to the re-electrolysis of using 20% spirit of salt (HCl) electrolyte solution;
Figure 11 shows another EDX data and the corresponding SEM image of another nano-scale pure silicon sample, and described another nano-scale sample separates according to embodiment of the invention alloy from second crucible during re-electrolysis;
Figure 12 show according to behind the embodiment of the invention some pure silicon particles in natural separation alloy by the amorphous band of the residue alloy casting in second crucible;
Figure 13 shows when not using direct heat oven and induction furnace heating ionogen regularly during once electrolytic, the test parameter and the test result data that observe when making the alloy that contains pure silicon according to the embodiment of the invention described herein in first crucible;
Figure 14 and Figure 15 displaying are used for from the sectional view of the alternative embodiment of the device of alloy divided silicon;
Figure 16 shows the sectional view of the embodiment of the invention, and wherein second crucible lining is placed in first crucible between first crucible lining and alloy anode; With
Figure 17 shows the sectional view of another embodiment of the present invention; With
Figure 18 displaying shows the experimental data of testing according to the silicon sample of embodiment of the invention manufacturing.
Figure 19 shows the phasor of cupro silicon.
Embodiment
With reference to description of drawings the preferred embodiments of the present invention and be described below.
Fig. 1 and Fig. 2 describe the schema for the manufacture of the method steps of the embodiment of pure silicon.Among the described embodiment, term " pure silicon " refers to solar battery grade silicon in this article.The device (1) that is used for the method steps that execution graph 1 and Fig. 2 describe is showed among Fig. 3 and comprises for receiving electrolytical first crucible (2), be arranged in first crucible lining (3) (it makes ionogen separate with the inside peripheral wall (2a) of first crucible (2)) in first crucible (2), the thermal source that is used for heating first crucible (2), be used for after ionogen (4) is by the thermal source fusion, ionogen (4) being applied the electrolysis device of electrolysis and be used for stirring the device of fused electrolyte (4) during electrolysis.Produce pure silicon and anode (5) formation alloy by electrolysis.Then can use hereinafter in greater detail tripping device and method extract pure silicon from alloy.
In the weight of ionogen (4), the ionogen that uses among the embodiment described herein comprises about 87% sodium aluminum fluoride particle, 10% calcium oxide particle and 3% quartzy particle.Before in being deposited on first crucible (2), by making the fusion and then make the material of fusion solidify to make ionogen (4) together under 1200 ℃ temperature of sodium aluminum fluoride, calcium oxide and quartzy particle.The gained density of this ionogen (4) is about 3 grams/cubic centimetre.
First crucible (2) is to be formed and had for the inner recesses (2c) that receives ionogen (4) by carbon material.Recess (2c) is cylindrical and be to be defined by inside peripheral wall (2a) and bottom (2b).In alternative embodiment, first crucible (2) and inner recesses (2c) need not cylindrical.Perhaps, first crucible (2) can be formed by the material as nitric acid silicon or carbofrax material.No matter use which kind of material, first crucible (2) material require can produce heat in being placed in induction furnace the time or in being placed in direct heat oven the time with relative efficient manner conduction heat.
The electrolysis device comprises anode (5) and negative electrode (7), and it is connected to positive terminal and the negative pole end of power supply (not shown).When making negative electrode (7) and anode (5) contact storing with fused electrolyte (4) and produce potential difference between anode (5) and negative electrode (7), fused electrolyte (4) experiences electrolysis, thereby causes the generation of pure silicon.
In weight alloy, anode (5) comprises the alloy of copper and about 3% pure silicon particle.At first by making copper fusion and make up to form alloy with about 3% pure silicon particle under about 1200 ℃ temperature.Comprising 3% pure silicon particle in the alloy anode helps the melt temperature of alloy is set at the temperature that applies during the electrolysis.Although it is contemplated that to make the pure silicon and the copper that surpass 3 weight % be combined to form alloy anode at first, think that this content is the suitable minimum level of setting suitable fusing point.
Negative electrode (7) comprises carbon-point, and it is to form by compression purifying carbon dust.Before compression, come the purifying carbon dust by applying any impurity that pickling and chlorine washes to remove in the carbon dust.Carbon-point controllably is placed and only after heating ionogen (4) to form fused electrolyte (4) it is reduced in the crucible recess and contacts with ionogen (4).In scale operation, can carry out the arrangement of carbon cathode (7) by driving the known any automation installing system of those skilled in the art.In the process of test embodiment described herein, manually reduce carbon-point it is contacted with fused electrolyte.
The cylindrical tubular configuration of first crucible lining (3), its first crucible recess of fitting.First crucible lining (3) is with inside peripheral wall (2a) complementation of the first crucible recess (2c) and near inside peripheral wall (2a).Therefore, in use, the barrier that first crucible lining (3) is provided for making the ionogen (4) in the recess (2c) to separate with the inside peripheral wall (2a) of the first crucible recess (2c).The existence that it should be noted that first crucible lining (3) can help to prevent that ionogen (4) is inhaled in first sidewall of crucible (2a), and ionogen (4) is inhaled into the efficient that will reduce electrolytic process in first sidewall of crucible (2a).In addition, be inhaled in first sidewall of crucible (2a) because first crucible lining (3) helps to block ionogen (4), therefore cause that more ionogen (4) is drawn towards alloy anode, thereby further improve the efficient of electrolytic process.
In this embodiment, first crucible lining (3) is to be formed by quartz.Along with quartz lining during the electrolysis (3) gradually by ionogen (4) corrosion, produce thus electrolysis the time limitation of time length is taken place and therefore produce can be used for producing by electrolysis the restriction of the time total amount of pure silicon.For managing to prolong the electrolysis time length, it is quartzy to use other low-corrosiveness material (as calcium oxide, magnesium fluoride and Sodium Fluoride) to replace.If use quartz material as first crucible lining (3), can be provided for expediently then keeping that the quartzy particle ratio in the fused electrolyte (4) is in the required an amount of extra quartzy particle of predeterminated level during the electrolysis.
Perhaps can use pure silicon to form first crucible lining (3), because this material is not inclined under the temperature that applies fusion in electrolytic process and it often can not corrode because interacting with ionogen (4).Because pure silicon first crucible lining (3) is not inclined to corrosion, therefore to compare with using corrodible first crucible lining (3) (for example quartzy first crucible lining (3)) time, it not is too crucial problem that the thickness of pure silicon first crucible lining (3) is selected.Therefore, when the scale operation pure silicon, estimate that it will be especially favourable using pure silicon first crucible lining (3), thereby continue to save production cost because it can be reused.In fact, use pure silicon first crucible lining (3) also to help to reduce and the practical complicacy of using corrodible first crucible lining (3) to be associated, when using corrodible first crucible lining (3), need termly new first crucible lining (3) to be inserted in first crucible (2) again.During the test embodiment of the invention, use the quartz lining of about 9.5 cm diameters.
Perhaps and/or in addition, also can come natural first crucible lining (3) of generation first crucible (2) in by the temperature of suitably regulating first crucible (2) interior region.For example, thus can set the electrolytical temperature that temperature that negative electrode (7) locates be relatively higher than the inside peripheral wall (2a) that is positioned at contiguous first crucible (2) and implement by producing the suitable temp gradient.Because the temperature that negative electrode (7) rises is higher relatively with respect to the ionogen of the inside peripheral wall of contiguous first crucible (2), so electric-arc heating is particularly useful for producing the suitable temp gradient.If the temperature of negative electrode (7) is set at the temperature of ionogen (4) of the inside peripheral wall (2a) of (for example) 980 ℃ and contiguous first crucible and is set at 900 ℃ or be lower than 900 ℃, will make natural first crucible lining (3) of inside peripheral wall (2a) of contiguous first crucible (2) solidify so and the inner remaining ionogen of first crucible (2) (4) will keep the fusion form by means of negative electrode (7) temperature.It is favourable producing natural first crucible lining (3), need not to provide independent first crucible lining (3) because it makes, thereby reduces production costs and the complicacy of implementation process.
When testing embodiment described herein, use the main thermal source of direct heat oven conduct to be used for heating the alloy in first crucible (2), ionogen (4) and first crucible (2).But, be expected at and can use electric-arc heating source instead hot in nature in the alternative embodiment, thereby make the resistance in the electrolyte medium between anode (5) and the negative electrode (7) produce heat.Can easily understand, anode (5) and negative electrode (7) be at a distance of more far away, then the resistance of Chan Shenging more greatly and so the heat transferred in the ionogen (4) in first crucible (2) more big.Perhaps and/or in addition, can use induction furnace that induction heating is provided.
Use agitation means during electrolysis, to continue to stir fused electrolyte (4).Stir fused electrolyte (4) and help in ionogen (4), to produce contacting between ionic current and increase ionogen (4) and the molten alloy anode (5).Advantageously, use induction furnace in fused electrolyte, providing stirring action during the electrolysis inherently.Therefore, can use induction furnace as secondary heat source be used for to regulate temperature and also to can be used as for the mechanism of during electrolysis, stirring fused electrolyte (4).This will help to be reduced to the cost of acquiring due to the independent special whipping device.In addition, because the stirring that is provided by induction furnace is to interact by electromagnetic force but not with the direct mechanical of fused electrolyte (4) to produce, therefore can reduce required time of servicing machine agitation means and cost.Thereby induction furnace can be configured to apply impulse of current and stir fused electrolyte (4).Certainly, can use mechanical stirrer where necessary in other embodiments of the invention.
In alternative embodiment, can use special magnetic stirrer spare magnetic to stir alloy in first crucible (2).
Now according to the embodiment of the invention method of using said apparatus to make pure silicon is described.
At first, liner and recess are inboard to be cooperated as making in the crucible recess by quartzy first crucible lining (3) is slipped into.This step is represented by the block among Fig. 1 (100).Then deposition anode alloy (5) contacts its bottom with first crucible (2) in crucible recess (2c).Then under about 950 ℃ to 980 ℃ temperature, heat first crucible (2) so that alloy molten by direct heat oven.This step is represented by the block among Fig. 1 (110).
In case alloy (5) fusion is then further heated first crucible (2) so that the ionogen fusion becomes fused electrolyte (4) under molten alloy (5) top deposition solid ionogen (4) and the temperature at least 900 ℃ in the first crucible recess (2c).These steps are by the block among Fig. 1 (120) and block (130) expression.
Then, make it contact to begin the electrolysis of fused electrolyte (4) with fused electrolyte (4) by reducing carbon-point.This step is represented by the block among Fig. 1 (140).Because negative electrode (7) extremely directly is electrically connected with power-and alloy anode is electrically connected with power positive end by first crucible (2) (itself being electro-conductive material), the potential difference of anode and negative electrode (7) promotes electrolysis.
During the embodiment that test is described herein, apply 6 volts to the 8 volts voltages in the scope between anode (5) and negative electrode (7), this voltage causes that about 40 amperes to 60 amperes electric current flows between anode (5) and negative electrode (7) by the fused electrolyte medium.Fused electrolyte (4) is contained in the quartz crucible of about 9.5 cm diameters and across about 70.8800938 square centimeters electrolyte meter area and is exposed to about 1 ampere/square centimeter current density.
Note that if the current density setting is too high, then may cause the infringement of first crucible lining (3) and/or first crucible (2) is accelerated.It will be understood by one of ordinary skill in the art that the variation of the value of the size of first crucible (2), the current density that applies and bath surface will influence the productive rate size of the pure silicon of making according to embodiment described herein.The Productivity leads usually can be according to the following formula proximate calculation:
Productive rate=electric current (A) * [electrolysis constant (0.262 gram/ampere hour)] * [electrolysis time (hour)] u
During electrolysis, the temperature that keeps fused electrolyte (4) be about 900 ℃ to 1000 ℃ to prevent that fused electrolyte (4) from solidifying.Usually, when fused electrolyte (4) being remained on relative comparatively high temps following time during electrolysis, pure silicon production efficiency obtains improvement.But, should note some and select the temperature relative restrictions.At first, find that the temperature that keeps fused electrolyte (4) during electrolysis is that about 980 ℃ temperature can produce special ideal results during the embodiment according to test description herein.Temperature is higher than 980 ℃ of evaporation and viscositys of more easily improving fused electrolyte (4), thereby hinders pure silicon production efficiency and finally may make electrolysis stop.Fused electrolyte (4) be equal to or less than 980 ℃ temperature and often can not improve evaporation and the viscosity of fused electrolyte (4), but temperature should not be lower than 900 ℃, because will solidify when being lower than 900 ℃.
Along with electrolysis is carried out, stir fused electrolyte (4) to increase the flux that the pure silicon particle that produces during the electrolysis contacts with alloy anode (5).At test period, use automation to stir.But, use induction furnace to come magnetic to stir fused electrolyte (4) by fused electrolyte (4) being applied impulse of current expediently.This step is represented by the block among Fig. 1 (150).
During electrolysis, in the weight of ionogen (4), the ratio that should keep quartzy particle in the ionogen (4) is about 3%.For satisfying this requirement, use the quartzy particle in the cycle sensor ground measurement ionogen (4) and use allocation member to be assigned in the fused electrolyte (4) to compensate any consumption by the quartzy particle of controllable mode with additional quantity as required.As mentioned above, if use quartz material as first crucible lining (3), then can utilize the consumption of quartzy particle in the fused electrolyte (4) during the quartzy particle compensation electrolysis in the liner, thereby keep the ratio of required quartzy particle.This step is represented by the block among Fig. 1 (160).
Utilize above-described embodiment, the pure silicon (6) that forms alloy with anode (5) is showed among Fig. 5 and Fig. 6.Can use isolation technique from alloy (5), to isolate pure silicon (6).
After the limited period, during the solubility limit of the pure silicon in reaching alloy, the electrolysis in first crucible (2) will stop.This step is represented by the block among Fig. 1 (170).During the test embodiment of the invention, find, when adding thermalloy (5) under the temperature between about 950 ℃ to 980 ℃, in the weight of alloy (5), when the pure silicon (6) in the alloy (5) reaches about 25% the time, pure silicon (6) no longer can dissolve with alloy (5).Reach time that solubility limit spends will depend on a number of factors (surface-area that comprises the fused electrolyte (4) that electrolysis takes place).But, when testing embodiment described herein, find in the time of about 8 hours, to reach this solubility limit.Just productive rate and the purity of the pure silicon (6) of the embodiment manufacturing of basis description herein be it seems, this should be understood that representing to compare existing production method is significantly improved in efficient.
In this embodiment, with reference to figure 2, then begin from alloy, to separate pure silicon in second crucible (not shown) by at first using suction device or any other suitable mechanical extraction member that molten alloy (5) is transferred to.Second crucible can be made by any material that is suitable for being exposed to the temperature about 800 ℃ to 1000 ℃.But, be used to form the material reply alloy of second crucible and/or melting salt be inertia-be its not should with alloy or any other melting salt generation chemical reaction.This step is represented by the block among Fig. 2 (200).
By about 2 ℃ to 3 ℃/minute rate of cooling the molten alloy in second crucible is maintained at about under the temperature between 800 ℃ to 850 ℃, thereby some pure silicons in the molten alloy (5) will be tended to because thermodynamics and natural separation from alloy (5).Float to the top of molten alloy (5) on pure silicon (6) (its density is lower than copper) is natural.This step is represented by the block among Fig. 2 (210).During the test embodiment of the invention, have been found that the weight in alloy (5), about 11% pure silicon (6) particle will on float to melts the top become solid pure silicon (6).The pure silicon that is floating (6) fusion again becomes ingot.
Have been found that the pure silicon (6) of the natural separation of this form is applicable to the solar battery grade application and expect that its efficient is at least about 18% that at test period this is consistent by the performance of the solar battery grade polysilicon of siemens (Siemens) manufacturing with tradition.Use melting salt to cover molten alloy (5) in second crucible to alleviate reoxidizing of solid pure silicon (6) of floating.
In certain embodiments, when natural when isolating in about 11% pure silicon of the weight of molten alloy (6) in the alloy from second crucible, remaining alloy in second crucible can be drawn again and get back in first crucible.Again the molten alloy of Yin Ruing will sink to first crucible (2) bottom and further promote electrolytic process.
Perhaps, can be with the residue alloy casting in second crucible or extruding for amorphous band or mechanical disruption or grind and be the powder of micron to the nano-scale alloy particle, residue alloy in second crucible drawn again when substituting the pure silicon particle of in the alloy from second crucible, isolating predetermined percentage and gets back in first crucible.It will be understood by one of ordinary skill in the art that the mechanical mill alloy is more prone to introduce a large amount of impurity.The test of the embodiment of the invention so far relates to mechanical disruption alloy in second crucible and is not the band casting.This step is represented by the block among Fig. 2 (220).
The method and apparatus that uses when casting amorphous band can be configured to look the microstructure that rate of cooling during the band casting is controlled nano-scale pure silicon particle in the band self.Subsequently the nano-scale pure silicon particle that can from band, separate according to embodiment described herein can be greatly about 10 nanometers in 60 nanometer range.Figure 12 shows the amorphous band by alloy casting.
Then, again band or powder are immersed in that the back applies re-electrolysis to band or powder in the electrolyte solution.Among the described embodiment, use the electrolyte solution with 10% hydrochloric acid (HCl) and 20% hydrochloric acid (HCl) separately in different occasions in this article, the result of these variations is showed in respectively among Fig. 9 and Figure 10.During re-electrolysis by in electrolyte solution, coming the acidity of regular replenishment electrolyte solution to keep suitable pH value and Cl the HCl gas pumping -Content.It will be understood by one of ordinary skill in the art that in alternative embodiment, alloy can be immersed in other electrolyte solution and (comprise dehydration acetic acid, iodine solution (being liquor kalii iodide), hydrazoic acid (HN 3), acetone, dense ethanol or its combination) in.This step is represented by the block among Fig. 2 (230).
During re-electrolysis, apply less than about 1 ampere electric current suitably from alloy, to remove copper.After applying re-electrolysis, electrolyte solution contains Cu/Cu+/Cu++ and nano-scale pure silicon particle.Then use centrifugal device from electrolyte solution, to separate nano-scale pure silicon particle by centrifugal motion.This step is represented by the block among Fig. 2 (240).In alternative embodiment, can during re-electrolysis, apply the electric current greater than 1 ampere, but this may cause silicon oxidation.If the generation silicon oxidation then can use acid (as HF(hydrofluoric acid)) to corrode silicon (quartz) zone of oxidation to obtain nano-silicon.
Because nano-scale pure silicon particle is more prone to and oxygen reaction, therefore nano-scale pure silicon particle is stored in as in the material of dense ethanol to alleviate the reaction with free oxygen.This step is represented by the block among Fig. 2 (250).
Can with after the sepn process from the alloy strip of casting or powder the copper that extracts draw again and get back to first crucible (2) to promote the electrolytic process in first crucible (2).It will be understood by one of ordinary skill in the art that this can be considered more effective conserve energy mode, because the molten alloy that has separated is 800 ℃ to 850 ℃ and will only needs 100 ℃ to 150 ℃ energy to continue the electrolysis in first crucible (2).
In other embodiments, thus can be in second crucible by in anaerobic closed district, making band or powder and HCl gas or chlorine reaction come from alloy, to remove copper with HCl gas or chlorine flushing band or powder.Then must or use solubilized CuCl by mechanical means 2Appropriate solution flushing remove CuCl 2Then can remove nano-scale pure silicon particle.It will be understood by one of ordinary skill in the art that CuCl 2Has paramagnetism.Therefore, can be to containing CuCl 2Powder apply magnetic field from powder, to remove CuCl 2If reduce the pollutent of introducing when oxygen solution washes with containing simultaneously.Advantageously, by wash the CuCl that band or powder form with HCl gas or chlorine 2With any dense ethanol that reoxidizes that is easy to be dissolved in for alleviating nano-scale pure silicon particle.
It will be understood by one of ordinary skill in the art that in addition, in alternative embodiment, above-mentionedly can be similarly move on to the neutralization of second crucible and directly the alloy first crucible is not carried out under the situation of natural separation pure silicon from alloy in advance not being about to alloy in first crucible (2) earlier for the method and apparatus that from alloy, separates pure silicon at second crucible.Therefore, can form band or powder and band or powder are applied electrolysis by making to contain in first crucible (2) in the alloy of weight alloy 25% pure silicon particle, then from electrolyte solution, separate the nano-scale pure silicon particle that forms and make alloy be exposed to above-mentioned tripping device and method.
It will be understood by one of ordinary skill in the art that in addition, above-mentioned for the apparatus and method of separating pure silicon from alloy and the nonessential alloy that contains pure silicon that is applied to according to embodiment formation described herein, and can be with the alloy of other alternative apparatus and method manufacturings.
Fig. 4 (a)-4(b), 5(a)-5(b), 6(a)-6(b) with 7(a)-7(b) be illustrated in EDX data and corresponding SEM image according to 4 different sample area of the alloy that produces in first crucible behind the embodiment of the invention once electrolytic described herein.The ratio of pure silicon and copper in the alloy of each analytic sample that it will be understood by one of ordinary skill in the art that is with carrying out different variation the in alloy position that sample reads.For example, Fig. 5 (a) and Fig. 5 (b) (it shows that pure silicon component (namely 100%) content is relatively higher than copper content (can ignore)) are to obtain at the alloyed region that mainly contains pure silicon.On the contrary, since sample read be in alloy between silicon and the copper at the interface or near interface carry out pure silicon component relatively low (namely 68.83%) in Fig. 4 (a) and Fig. 4 (b) demonstration alloy.
Fig. 8 shows EDX data and the corresponding SEM image of pure silicon, described pure silicon be since in the alloy different densities between pure silicon and the copper and in second crucible from alloy natural the separation.The pure silicon of showing among Fig. 8 is suitable for fusion becomes ingot.
Fig. 9,10 and Figure 11 show EDX data and the corresponding SEM image of nano-scale pure silicon particle, described nano-scale pure silicon particle be according to re-electrolysis described herein and treatment process from the alloy manufacturing with separate.The nano-scale pure silicon particle of showing among Fig. 9 relates to during re-electrolysis and to use the nano size particles that has the electrolyte solution of 10% hydrochloric acid (HCl) and show among Figure 10 to relate to use the electrolyte solution with 20% hydrochloric acid (HCl) during re-electrolysis.The existing aluminium that shows in the EDX data is to introduce during the mechanical disruption process of alloy, and can eliminate in fact by using more Precise Alloy to mill in experiment subsequently.In another experiment, can also be stored in the dense ethanol to alleviate that it reoxidizes by the nano-scale pure silicon particle that will separate is that quartz is eliminated the oxygen component in fact.Therefore, think that can obtain purity according to aforesaid method surpasses 99% silicon in fact.
Figure 13 is illustrated in the data that produces during the test embodiments of the invention when making pure silicon.The average efficiency of using direct heat oven and induction furnace to obtain during the once electrolytic in first crucible is respectively about 71% and 75%.The 4th row among Figure 13 (" gram (before the electrolysis) ") represent that once electrolytic begins the pure silicon amount in the preceding alloy anode, and the pure silicon amount in the alloy behind the 5th row (" gram (after the electrolysis) ") the middle generation of expression first crucible (2) once electrolytic.Can determine efficient by the relation between the energy that consumes in pure silicon net gain and the process.
In alternative embodiment, after in first crucible (2), carrying out electrolysis, can be by alloy (5) being placed in second crucible of being made by SiC (7) and the alloy (5) in second crucible (7) being carried out re-electrolysis come divided silicon (6) from alloy (5).Re-electrolysis is to carry out under the situation of the polarity reversal of anode (5) and negative electrode (10).Second crucible (7) should not made by carbon, because silicon will form SiC with the carbon material reaction.Exemplary tripping device is showed among Figure 14.
Re-electrolysis be to use 600 amperes to 800 amperes in the scope electric current and about 6 volts to 7 volts voltage carry out.Used current density approximately is 0.1 ampere/square centimeter to 2.0 amperes/square centimeter.
Re-electrolysis is at least a the carrying out (approximate weight per-cent) of using in second crucible (7) in the following electrolyte composition (8):
（i）10%K 2SiF 6、25%AlF 3、25%NaF、35%BaF 2、5%CaF 2；
(ii) 40%-70%Na 3AlF 6, 5%-20%K 2SiF 6, 5%-15%CaF 2, 5%-10%CaO; With
（iii）95%-99%Na 3AlF 6、1%-5%SiO 2。
Re-electrolysis produces being deposited on of about 300 meshes and contains silicon and electrolytical solid composite (11) on the alloy anode (5).Mixture is more near apart from anode (5), and silicon and electrolytical ratio are more high in the mixture (11).But, mixture (11) will on average contain the 20 weight % that have an appointment to 30 weight % silicon and about 70 weight % to 80 weight % ionogen.
Then, use induction furnace (12) or other suitable heating unit to make mixture (11) at least about 1450 ℃ or be higher than fusion under 1450 ℃ the temperature, thereby make i.e. coalescent sheet or the ingot of becoming in ionogen of silicon one cooling.After one cooling, then can use mesh gauze filter (13) as shown in Figure 15 from ionogen, to leach coalescent silicon chip or ingot.The silicon sample that test this embodiment according to the present invention makes, the result is showed by (B) among Figure 18.
Also can make mixture (11) return the cupro silicon that contains minimum 50 weight % silicon in about 1000 ℃ of following fusions.Should be appreciated that the melt temperature of alloy will depend on the specified weight per-cent of silicon in the alloy and decide.Then, can carry out that controlled process of cooling makes silicon since solubility limit and density variation and on float to the top.Rate of cooling can be that the silicon of predetermined weight percent is cooled to about 800 ℃ for about 2 ℃ to 3 ℃/minute in the alloy molten thing.At 800 ℃ or following, alloy still is liquid phase, obtains silicon thereby silicon has separated from alloy molten thing self and it is poured out.After separating pure silicon, the residue alloy will contain about 13 weight % to 15 weight % silicon.The about 50 weight % silicon particles of minimum needs in the alloy are so that silicon nucleation and growth and therefore separate.The free energy of nucleation equation, crystal growth equation and described silicon particle only is the Several Factors that how to influence according to specific and controlled rate of cooling divided silicon from alloy.
In described any previous embodiment, second crucible lining of being made by atresia SiN or SiC material (9) can be arranged between alloy (5) and first crucible lining (3) in first crucible (2) in this article.Existence second crucible lining (9) helps to prolong the electrolytic process in first crucible (2) between alloy (5) and first crucible lining (3).
During the electrolysis in first crucible (2), keep second crucible lining (9) to be immersed in fact under the highest level of molten alloy (5).Second crucible lining (9) is immersed in and can alleviates ionogen (4) under the highest level of molten alloy (5) and be inhaled in second crucible lining (9).
Another embodiment that makes pure silicon is showed among Figure 17.This embodiment relates to the device that under the situation of not using any crucible lining the ionogen (15) that contains quartz is carried out electrolysis at crucible (14).Use two carbon-points (17a, 17b) to carry out electrolysis as the electrode in the ionogen, wherein two carbon nodes have an amount of starting material that are used for carrying out electrolytic process.Should not use as carbon or Al among this embodiment 2O 3Material because it tends to and electrolyte reaction and form pollutent.
At first quartz wedge or quartz plate are placed in the crucible (14) and at the Powdered quartz of electrolysis period interpolation to guarantee supply silicon particle during electrolysis.Electrolysis produces the accumulated solids mixture (16) that is deposited in the crucible (14), contains have an appointment 20 weight % silicon and 80 weight % ionogen in the mixture (16).Silicon in the mixture (16) has about 300 mesh size of particles.
Use induction furnace (18) or other suitable heating arrangements to make mixture (16) fusion, silicon one cooling is namely coalescent in ionogen to become small-sized ingot thereby make.Then drop to when being lower than about 1414 ℃ (being the solidification point of silicon) when composite temperature, can use the mesh gauze filter (13) as showing among Figure 15 from ionogen, to leach silicon ingot.Perhaps, found to use ethanol divided silicon from mixture (16) of 40% to 100% concentration, thereby mixture (16) is decomposed earlier and used alcohol flushing.Solid electrolyte will float and silicon will keep submergence.
Discovery boron and phosphorus and ionogen form compound and evaporate during electrolysis.The silicon sample that this embodiment according to the present invention makes, the back result is showed by (A) among Figure 18 after tested.
Under in the field tool know that usually the knowledgeable should be appreciated that, can be in the modifications and variations of under the situation that does not depart from category of the present invention the present invention being made except specific description.All described modifications and variations all can be by apparent to the those skilled in the art, and it should be considered as belonging to above in the broadly described spirit of the present invention and category scope.Should be appreciated that, the present invention includes all described modifications and variations.The present invention also comprise relate to individually or jointly in the specification sheets or indicate in steps with feature and described step or feature in any both or above any combination and all combinations.
In this specification sheets the reference of any prior art all do not represented and should not be considered as confirming or propose in any form that prior art forms a part of generally acknowledging general knowledge.

Claims (23)

1. make the method for pure silicon from ionogen for one kind, wherein said method may further comprise the steps:
(i) in first crucible, heat described ionogen to form fused electrolyte; With
(ii) by providing potential difference that electrolysis is applied to described fused electrolyte between anode and negative electrode, described anode and negative electrode are suitable for and described fused electrolyte electricity/ionic connection;
Wherein when just applying electrolysis, stir described fused electrolyte and can be dissolved with described anode by the pure silicon that described electrolysis produces and form alloy.
2. method according to claim 1, wherein said ionogen comprises sodium aluminum fluoride, calcium oxide particle and quartzy particle.
3. method according to claim 2, wherein in described electrolytical weight, described ionogen comprises about 82% to 94% sodium aluminum fluoride particle.
4. according to claim 2 or the described method of claim 3, wherein in described electrolytical weight, described ionogen comprises about 3% to 15% calcium oxide particle.
5. according to the described method of arbitrary claim in the claim 2 to 4, wherein in described electrolytical weight, described ionogen comprises about 3% quartzy particle.
6. according to the described method of arbitrary claim in the claim 2 to 5, wherein in described electrolytical weight, described ionogen comprises about 87% sodium aluminum fluoride particle, 10% calcium oxide particle and 3% quartzy particle.
7. according to the described method of arbitrary claim in the claim 2 to 6, it controllably adds quartzy particle to keep the step with the about 3% quartzy particle of described electrolyte weight in fact in described ionogen during being included in electrolysis in described ionogen.
8. according to the described method of arbitrary claim in the aforementioned claim, wherein said first crucible comprises at least a in carbon, nitric acid silicon and the carbofrax material.
9. according to the described method of arbitrary claim in the claim 1 to 8, wherein said first crucible comprises by inside peripheral wall with for the recess that receives described electrolytical bottom portion defining.
10. method according to claim 9, it is included in the step of arrangement first crucible lining between inherent described first crucible of the described first crucible recess and the described ionogen.
11. according to the described method of arbitrary claim in the aforementioned claim, it is included in the step of arranging second crucible lining between the inherent described alloy anode of the described first crucible recess and described first crucible lining.
12. method according to claim 11, wherein said second crucible lining comprise at least a in SiC and the SiN material.
13. according to claim 11 or the described method of claim 12, be immersed under the described anode during the electrolysis of wherein said second crucible lining in described first crucible.
14. according to the described method of arbitrary claim in the aforementioned claim, thereby wherein (ii) come from described alloy divided silicon by described alloy being carried out re-electrolysis formation silicon and electrolytical solid composite the back in step.
15. method according to claim 14, the polarity reversal of wherein said anode and negative electrode.
16. according to claim 14 or the described method of claim 15, wherein said re-electrolysis is independently to carry out in the crucible with described first crucible.
17. according to the described method of arbitrary claim in the claim 14 to 16, wherein said independent crucible comprises the SiC material.
18. according to the described method of arbitrary claim in the claim 14 to 17, wherein said re-electrolysis is to use at least a the carrying out in the following electrolyte composition:
（i）10%K 2SiF 6、25%AlF 3、25%NaF、35%BaF 2、5%CaF 2；
(ii) 40%-70%Na 3AlF 6, 5%-20%K 2SiF 6, 5%-15%CaF 2, 5%-10%CaO; With
（iii）95%-99%Na 3AlF 6、1%-5%SiO 2。
19. according to the described method of arbitrary claim in the claim 14 to 18, the wherein said mixture fusion under at least about 1450 ℃ temperature that is deposited on the described anode, thus make silicon when cooling, in described ionogen, gather into sheet or ingot.
20. method according to claim 19 wherein uses strainer to leach described coalescent silicon chip or ingot from described ionogen.
21. a method of making pure silicon, it may further comprise the steps:
(i) in crucible, carry out electrolysis to containing quartzy ionogen, wherein form and contain silicon and described electrolytical solid composite;
(ii) follow, make described mixture fusion, the described silicon particle in the wherein said mixture is coalescent in described ionogen when cooling;
(iii) follow, when the temperature of described fusion mixture is lower than about 1414 ℃, from described ionogen, leach described coalescent silicon.
22. method according to claim 21, it periodically adds Powdered quartz to keep the step of supply silicon particle during being included in described electrolysis in described crucible.
23. according to claim 21 or the described method of claim 22, use two carbon nodes in the wherein said electrolysis.
CN2011800616056A 2010-12-20 2011-12-20 Method and apparatus for producing silicon Pending CN103261095A (en)

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