WO2012083480A1

WO2012083480A1 - Method and apparatus for producing pure silicon

Info

Publication number: WO2012083480A1
Application number: PCT/CN2010/002087
Authority: WO
Inventors: Albert Pui Sang LAU; Lee Cheung LAU
Original assignee: Epro Development Limited
Priority date: 2010-12-20
Filing date: 2010-12-20
Publication date: 2012-06-28
Also published as: TW201231391A; WO2012083588A1; JP2014502671A; EP2655252A1; DE112011104441T5; US20130277227A1

Abstract

Provided are a method and an apparatus for producing pure silicon from an electrolyte, The method includes the steps of :(i) heating the electrolyte in a first crucible to form a molten electrolyte; and (ii) applying electrolysis to the molten electrolyte by providing a potential difference between an anode and cathode which are adapted for electrical/ionic communication with molten electrolyte; wherein the molten electrolyte is stirred as electrolysis is being applied and pure silicon produced as a result of the electrolysis is soluble with the anode to form an alloy. Also provided are the pure silicon and electrical-grade silicon material obtained by the method, and a solar cell and a battery made from the pure silicon.

Description

METHOD AND APPARATUS FOR PRODUCING PURE SILICON

Technical Field

[0001] The present invention relates to a method and apparatus for producing silicon, and in particular, silicon of suitable purity for use in solar-cell applications and the like.

Background of the Invention

[0002] Solar-cell technologies are perceived to be an environmentally-friendly alternative to traditional forms of energy production such as those utilising fossil fuels. Accordingly, solar-cell technologies represents a significant commercial market.

[0003] Currently, technology developed by Siemens (the "Siemens Process") is widely considered to be the leading process for the production of silicon which is of suitable purity for use in solar-cell applications. In the Siemens process, high-purity silicon rods are exposed to trichlorosilane at 1150°C such that the trichlorosilane gas decomposes and deposits additional silicon onto the rods to enlarge them. The Siemens process is however considered to be both relatively expensive and not environmentally-friendly. In energy terms, it is estimated that the Siemens process expends approximately 200 MW.Hr of electricity in order to produce 1 ton of solar- grade silicon.

[0004] Carbothermic reduction processes have also been developed as an alternative to the Siemens process. However, these processes do not produce silicon which is of solar-grade quality since impurities such as boron and phosphorous, which are inherently contained in carbon, cannot be removed to suitably low levels (i.e. to levels in the parts-per-million or parts-per-billion).

[0005] Accordingly, there is a perceived need for an alternative solution in seeking to address the above-described problems associated with production of solar-grade silicon. Summary of the Invention

[0006] The present invention seeks to alleviate at least one of the above-described problems.

[0007] The present invention may involve several broad . forms. Embodiments of the present invention may include one or any combination of the different broad forms herein described.

[0008] In a first broad form, the present invention provides a method of producing pure silicon from an electrolyte wherein the method includes the steps of:

(i) heating the electrolyte in a first crucible to form a molten electrolyte; and

(iii) applying electrolysis to the molten electrolyte by providing a potential difference between an anode and a cathode which are adapted for electrical/ionic communication with the molten electrolyte;

wherein the molten electrolyte is stirred as electrolysis is being applied whereby pure silicon is produced which is soluble with the anode to form an alloy.

[0009] Advantageously, the stirring of the molten electrolyte during electrolysis may assist in both generating ion-flow within the molten electrolyte, and, increasing the contact between the electrolyte and the molten alloy anode. The pure silicon may thereafter be readily segregated from the alloy using a segregation technique as discussed further below.

[0010] Preferably, the electrolyte may include cryolite, calcium oxide particles and quartz particles. More preferably, the electrolyte may comprise approximately between 82-94% cryolite particles by weight of the electrolyte. Also typically, the electrolyte may comprise approximately between 3-15% calcium oxide particles by weight of the electrolyte. Also preferably, the electrolyte may comprise approximately 3% quartz particles by weight of the electrolyte. More preferably, the electrolyte may comprise approximately 87% cryolite particles, 10% calcium oxide particles and 3% quartz particles by weight of the electrolyte. Also preferably, the present invention may include a step of controllably adding quartz particles to the molten electrolyte during electrolysis to substantially maintain approximately 3% quartz particles in the electrolyte by weight of the electrolyte.

[0011] Typically the first crucible may include at least one of a carbon, silicon nitrate and silicon carbide material. Preferably, the first crucible material may be adapted to generate heat if placed within an induction furnace, or, to conduct heat in a relatively efficient manner if placed in a direct heating furnace. Preferably, the first crucible may include a recess defined by an inner peripheral wall and a base for receiving the electrolyte. Typically, the recess may include a cylindrical shape.

[0012] Preferably, a crucible lining may be arranged inside the first crucible recess between the first crucible and the electrolyte. More preferably, the crucible lining may be contoured to substantially complement the inner peripheral wall of the first crucible. Preferably, the crucible lining may include a quartz material. Alternatively, the crucible lining may include at least one of a calcium oxide, magnesium fluoride, sodium fluoride and silicon material. Preferably, the material used as the crucible lining may be temperature resistant above at least approximately 1000°C. Preferably, the material used as the crucible lining may also be corrosion-resistant when exposed to the electrolyte during the electrolysis process. Advantageously, the crucible lining may assist in preventing electrolyte from being absorbed into the first crucible wall which tends to decrease efficiency in the electrolysis process. Additionally, because the crucible lining assists in blocking absorption of the electrolyte into the first crucible wall, this results in more electrolyte being directed towards the alloy anode to further improve efficiency of the electrolysis process.

[0013] Alternatively, the crucible lining may be formed from the molten electrolyte itself by generating a temperature gradient within the molten electrolyte wherein a portion of the molten electrolyte may be solidified adjacent the inner peripheral wall of the first crucible. Typically, electric arc heating may be used to create the temperature gradient between the cathode and molten electrolyte adjacent the inner peripheral wall of the first crucible.

[0014] Typically, the electrolyte may be heated using at least one of an arc furnace and an induction furnace. [0015] Typically, the molten electrolyte may be stirred using at least one of an induction furnace to magnetically stir the molten electrolyte, and, a mechanical stirrer.

[0016] Typically, the anode may include at least one of a copper, gold, silver, zinc and a magnesium material. Preferably, the anode includes a copper material. More preferably, the anode may comprise an alloy of copper and pure silicon. Typically, the pure silicon may comprise approximately 3% by weight of the alloy.

[0017] Preferably, prior to step (i) of the first broad form, the alloy may be positioned in the first crucible adjacent the base of the first crucible and melted in the first crucible whereby said electrolyte may be thereafter deposited into the first crucible on top of the melted alloy in readiness for step (i) of the first broad form to be performed. Typically, the alloy may be melted at a temperature of between approximately 950-980°C.

[0018] Typically, step (i) of the first broad form may include heating the electrolyte in the first crucible to a temperature of at least approximately 900°C in order to form the molten electrolyte.

[0019] Preferably, during step (ii) of the first broad form, the molten electrolyte may be maintained at a temperature whereby the molten electrolyte does not solidify. Typically, the temperature may be maintained between approximately 900-1000°C to alleviate solidification of the molten electrolyte. Preferably, the temperature may be maintained at approximately 980°C to prevent solidification of the molten electrolyte.

[0020] Typically, the molten electrolyte may be exposed to a current density of between approximately 0.1A/cm² to 2. OA/cm² in the first crucible when electrolysis is applied.

[0021] Typically, the cathode may include at least one of a carbon, copper, tungsten and a platinum material. Preferably, the cathode may be formed by pressing purified carbon powder into a solid rod. More preferably, the carbon powder may be purified by exposing the carbon powder to an acid wash and chlorine flushing to remove impurities.

[0022] Preferably, the cathode may be positioned in the first crucible after the electrolyte has been heated to form the molten electrolyte wherein the cathode is in electrical/ionic communication with the molten electrolyte.

[0023] Preferably, the present invention may include a step of segregating the pure silicon from the alloy after step (ii). Typically, the step of segregating the pure silicon from the alloy may be performed when pure silicon produced as a result of electrolysis may no longer be soluble with the alloy. Also typically, if the temperature of the alloy is between approximately 950-980°C, the pure silicon may no longer be soluble with the alloy when the pure silicon in the alloy is approximately 25% per weight of the alloy.

[0024] Typically, the step of segregating the pure silicon from the alloy may include adjusting the temperature of the alloy to between approximately 800-850°C whereby pure silicon is able to naturally segregate from the alloy. Also preferably, before adjusting the temperature of the alloy to between approximately 800-850°C, the alloy may be transferred into a second crucible. Preferably, the second crucible may include a material which is inert with respect to the alloy and/or molten salts. Typically, molten salts may be used to cover the segregated pure silicon to alleviate re-oxidisation of the pure silicon. Typically, the alloy in the second crucible may be reintroduced back into the first crucible when a predetermined percentage of pure silicon particles by weight of the alloy has segregated from the alloy. More typically, the predetermined percentage of pure silicon particles by weight of the alloy may include approximately 11% of pure silicon particles by weight of the alloy when the alloy in the second crucible is reintroduced into the first crucible.

[0025] Alternatively and/or additionally, instead of reintroducing the alloy in the second crucible back into the first crucible when the predetermined percentage of pure silicon particles has segregated from the alloy in the second crucible, the following steps may be applied: (i) forming the alloy in the second crucible into at least one of a tape and a powder; and

(ii) applying a secondary electrolysis to the tape or powder;

whereby pure silicon particles may be segregated from the alloy in the form of nano-sized pure silicon particles.

[0026] Typically, the tape may be formed by at least one of casting and extruding the alloy. Also typically, the powder may be formed by mechanically grinding or milling the alloy. Preferably, the powder may be formed by grinding the alloy in a controlled environment. Typically, the powder may include micron to nano sized alloy particles.

[0027] Preferably, the step of applying the secondary electrolysis may include submerging the tape or powder in an electrolyte solution. Typically the electrolyte solution may include at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions (i.e. potassium iodine solution), hydrazoic acid (HN3), acetone, concentrated alcohol and a combination thereof. Preferably, during the secondary electrolysis, the acidity of the electrolyte solution may be replenished.

[0028] Typically, a current of less than 1A may be applied during the secondary electrolysis.

[0029] Preferably, after the secondary electrolysis has been performed, the electrolyte solution containing the nano-sized pure silicon particles may be further processed to separate the nano-sized pure silicon particles from the electrolyte solution. Typically, the nano-sized pure silicon particles may be centrifugally separated from the electrolyte solution. Also preferably, the separated nano-sized pure silicon particles may thereafter be stored in a substance suitable for alleviating reaction with free oxygen. Typically the substance may include concentrated alcohol.

[0030] Yet alternatively, it would be understood by a person skilled in the art that any one of the above steps of segregating pure silicon from the alloy in the second crucible may be performed directly upon the alloy in the first crucible without being removed into a second crucible.

[0031] In a second broad form, the present invention provides an apparatus for producing pure silicon from an electrolyte including:

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; and

a stirring device 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.

[0032] Preferably the electrolyte may include cryolite, calcium oxide particles and quartz particles. More preferably, the electrolyte may comprise approximately between 82-94% cryolite particles by weight of the electrolyte. Also typically, the electrolyte may comprise approximately between 3-15% calcium oxide particles by weight of the electrolyte. Also preferably, the electrolyte may comprises approximately 3% quartz particles by weight of the electrolyte. More preferably, the electrolyte may comprise approximately 87% cryolite particles, 10% calcium oxide particles and 3% quartz particles by weight of the electrolyte.

[0033] Preferably, the present invention may include a dispenser for dispensing quartz particles in to the electrolyte during electrolysis to substantially maintain approximately 3% quartz particles in the electrolyte by weight of the electrolyte.

[0034] Typically, the first crucible may include at least one of a carbon, silicon nitrate and silicon carbide material. Preferably, the first crucible may include a recess defined by an inner peripheral wall and a base for receiving the electrolyte. Typically, the recess may include a cylindrical shape. [0035] Preferably, the present invention may include a crucible lining arranged inside of the first crucible recess between the first crucible and the electrolyte. Also preferably, the crucible lining may be contoured to substantially complement the inner peripheral wall of the first crucible. Typically, the crucible lining may include at least one of a quartz, calcium oxide, magnesium fluoride, sodium fluoride and silicon material.

[0036] Alternatively, the first crucible may include a crucible lining formed from solidification of a portion of the molten electrolyte as a result of a temperature gradient being generated within the molten electrolyte. Typically, the present invention may include an electric arc heating device for generating the temperature gradient between the cathode and molten electrolyte adjacent the inner peripheral wall of the first crucible.

[0037] Typically, the heat source may include at least one of an arc furnace and an induction furnace. Preferably, the arc furnace may be a primary source of heat.

[0038] Typically, the molten electrolyte may be stirred using at least one of an induction furnace to magnetically stir the molten electrolyte, and, a mechanical stirrer. Advantageously, an induction furnace may alleviate production costs by providing a dual function as a heat source and as a stirring device.

[0039] Typically, the anode may include at least one of a copper, silver, gold, zinc and a magnesium material. Preferably, the anode may include a copper material. More preferably, the anode may include an alloy of copper and pure silicon. Typically the pure silicon may comprise approximately 3% by weight of the alloy.

[0040] Preferably, the alloy may be melted in the first crucible adjacent the base of the first crucible and the electrolyte may be positionable on top of the alloy. Typically, the heat source may be adapted to melt the alloy at a temperature of between approximately 950-980°C. [0041] Typically, the heat source may be adapted to heat the electrolyte in the first crucible to a temperature of at least approximately 900^CC in order to form the molten electrolyte.

[0042] Preferably, during electrolysis of the molten electrolyte, the heat source may be adapted to maintain the molten electrolyte at a temperature whereby the molten electrolyte does not solidify. Typically, the heat source may be adapted to maintain the temperature of the molten electrolyte at between approximately 900-1000°C to prevent solidification of the molten electrolyte. Preferably, the heat source may be adapted to maintain the temperature of the molten electrolyte at approximately 980°C to prevent solidification of the molten electrolyte.

[0043] Typically, the molten electrolyte may be exposed to a current density of between approximately 0.1 A/cm² to 2. OA/cm² in the first crucible when electrolysis is applied.

[0044] Typically, the cathode may include at least one of a carbon, copper, tungsten and a platinum material. Preferably, the cathode may include a solid rod formed from pressed purified carbon powder. More preferably, the carbon powder may be purified by exposing the carbon powder to an acid wash and chlorine flushing to remove impurities. Also preferably, the cathode may be adapted for positioning in to the first crucible after the electrolyte has been heated to form the molten electrolyte whereby the cathode is in electrical/ionic communication with the molten electrolyte.

[0045] Preferably the present invention may include an apparatus for segregating the pure silicon from the alloy. Preferably, the apparatus for segregating the pure silicon from the alloy may be adapted to segregate the pure -silicon from the alloy when the pure silicon produced as a result of electrolysis is no longer soluble with the alloy. Also typically, if the alloy is at a temperature between approximately 950- 980°C, the pure silicon may no longer be soluble with the alloy when the pure silicon in the alloy is approximately 25% per weight of the alloy. [0046] Typically, the apparatus for segregating the pure silicon from the alloy may be adapted to adjust the temperature of the alloy to between approximately 800- 850°C whereby pure silicon may be able to segregate from the alloy. Also preferably, the apparatus for segregating the pure silicon from the alloy may be adapted to transfer the alloy into a second crucible before adjusting the temperature of the alloy to between approximately 800-850°C. Also preferably, the second crucible may include a material which may be inert with respect to the alloy and/or molten salts. Preferably, molten salts may be used to cover segregated pure silicon to alleviate re- oxidisation of the pure silicon. Typically, the present invention may be adapted for reintroducing the alloy in the second crucible back into the first crucible when a predetermined percentage of pure silicon particles by weight of the alloy has segregated from the alloy. More typically, the predetermined percentage of pure silicon particles by weight of the alloy may include approximately 11% of pure silicon particles by weight of the alloy.

[0047] Alternatively and/or additionally the apparatus for segregating the pure silicon from the alloy in the second crucible may include:

(i) an apparatus for forming the alloy in the second crucible into at least one of a tape and a powder; and

(ii) an apparatus for applying a secondary electrolysis to the tape or powder; whereby pure silicon particles may be segregated from the alloy in the form of nano-sized pure silicon particles.

[0048] Typically, the apparatus for forming the alloy into a tape may be adapted to cast or extrude the alloy into the tape. Also typically, the apparatus for forming the powder may be adapted for mechanically grinding or milling the alloy into the powder in a controlled environment. Preferably, the powder may be formed by grinding the alloy. Typically, the powder may include micron to nano sized alloy particles.

[0049] Preferably, the apparatus for applying the secondary electrolysis may be adapted for submerging the tape or powder in an electrolyte solution. Typically the electrolyte solution may include at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions (i.e. potassium iodine solution), hydrazoic acid (HN₃), acetone, concentrated alcohol and a combination thereof. Preferably, during the secondary electrolysis, the acidity of the electrolyte solution may be replenished.

[0050] Typically, the apparatus for applying the secondary electrolysis may be adapted for applying a current of less than 1 A during the secondary electrolysis.

[0051] Preferably the present invention may include an apparatus for separating nano-sized pure silicon particles in the electrolyte solution from the electrolyte solution after the secondary electrolysis has been applied. Typically this may include a centrifuge device for centrifugally separating the nano-sized pure silicon particles from the electrolyte solution. Also preferably, the present invention may include a storage apparatus for storing the separated nano-sized pure silicon particles in a substance suitable for alleviating reaction with free oxygen. Typically the substance may include concentrated alcohol.

[0052] Yet alternatively, it would be understood by a person skilled in the art that the apparatus for segregating the pure silicon from the alloy in the second crucible may be adapted to similarly separate pure silicon directly from the alloy in the first crucible without being removed into a second crucible.

[0053] In a third broad form, the present invention provides a method of producing pure silicon from an electrolyte wherein the method includes the steps of:

wherein a crucible lining is arranged inside the first crucible to substantially separate the molten electrolyte from an inner peripheral wall of the first crucible as electrolysis is being applied whereby pure silicon is produced which is soluble with the anode to form an alloy. [0054] In a fourth broad form the present invention provides an apparatus for producing pure silicon from an electrolyte including:

a first crucible for receiving the electrolyte;

a crucible lining arranged inside the first crucible to substantially separate the molten electrolyte from an inner peripheral wall of the first crucible as electrolysis is being applied to the molten electrolyte;

wherein pure silicon is produced which is soluble with the anode to form an alloy.

[0055] In a fifth broad form, the present invention provides a method of segregating pure silicon from an alloy containing at least one of a copper, gold, silver, zinc and a magnesium material alloyed with pure silicon particles, the method including the steps of :

(i) forming the alloy into at least one of a tape and a powder; and

(ii) applying electrolysis to the tape or powder;

[0056] Typically, the tape may be formed by at least one of casting and extruding the alloy. Also typically, the powder may be formed by mechanically grinding or milling the alloy in a controlled environment. Preferably, the powder is formed by grinding the alloy. Typically, the powder may include micron to nano sized alloy particles.

[0057] Preferably, the step of performing the electrolysis may include submerging the tape or powder in an electrolyte solution. Typically the electrolyte solution may include at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions (i.e. potassium iodine solution), hydrazoic acid (HN3), acetone, concentrated alcohol and a combination thereof. Preferably, during the electrolysis, the acidity of the electrolyte solution may be replenished.

[0058] Typically, a current of less than 1 A may be applied during the electrolysis.

[0059] Preferably, after the electrolysis has been performed, the electrolyte solution containing the nano-sized pure silicon particles may be further processed to separate the nano-sized pure silicon particles from the electrolyte solution. Typically, the nano-sized pure silicon particles may be centrifugally separated from the electrolyte solution. Also preferably, the separated nano-sized pure silicon particles may thereafter be stored in a substance suitable for alleviating reaction with free oxygen. Typically the substance may include concentrated alcohol.

[0060] In a sixth broad form, the present invention provides an apparatus for segregating pure silicon from an alloy containing at least one of a copper, gold, silver, zinc and a magnesium material alloyed with pure silicon particles, the apparatus including:

(i) an apparatus for forming the alloy into at least one of a tape and a powder; and

(ii) an apparatus for applying electrolysis to the tape or powder;

[0061] Typically, the apparatus for forming the alloy into a tape may be adapted to cast or extrude the alloy into the tape. Also typically, the apparatus for forming the powder may be adapted for mechanically grinding or milling the alloy into the powder. Preferably, the powder may be formed by grinding the alloy in a controlled environment. Typically, the powder may include micron to nano sized alloy particles.

[0062] Preferably, the apparatus for performing the electrolysis may be adapted for submerging the tape or powder in an electrolyte solution. Typically the electrolyte solution may include at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions (i.e. potassium iodine solution), hydrazoic acid (HN3), acetone, concentrated alcohol and a combination thereof. Preferably, during the electrolysis, the acidity of the solution may be replenished.

[0063] Typically, the apparatus for performing the electrolysis may be adapted for applying a current of less than 1A during the electrolysis.

[0064] Preferably the present invention may include an apparatus for separating nano-sized pure silicon particles in the electrolyte solution from the electrolyte solution. Typically this may include a centrifuge device for centrifugally separating the nano-sized pure silicon particles from the electrolyte solution. Also preferably, the present invention may include a storage apparatus for storing the separated nano- sized pure silicon particles in a substance suitable for alleviating reaction with free oxygen. Typically the substance may include concentrated alcohol.

[0065] In a seventh broad form the present invention provides a pure silicon produced in accordance with any one of the broad forms of the present invention described herein.

[0066] In an eighth broad form the present invention provides a solar cell including pure silicon produced in accordance with any one of the broad forms of the present invention described herein.

[0067] In a ninth broad form the present invention provides a battery including pure silicon produced in accordance with any one of the broad forms of the present invention described herein. Typically, an anode of the battery is formed from the pure silicon.

[0068] In a tenth broad form the present invention provides a crucible liner adapted for use in accordance with any one of the broad forms of the present invention described herein. In an eleventh broad form, the present invention provides an electrical-grade silicon material suitable for use in forming an integrated circuit element, said electrical-grade silicon material being produced in accordance with any one of the broad forms of the present invention described herein.

Brief Description of the Drawings

[0069] The present invention will become more fully understood from the following detailed description of a preferred but non-limiting embodiment thereof, described in connection with the accompanying drawings, wherein:

Figure 1 shows a flowchart of a method for producing pure silicon from an electrolyte in accordance with an embodiment of the present invention;

Figure 2 shows a flowchart of an embodiment method for segregating pure silicon from the alloy formed in accordance with the method steps depicted in Fig. 1 ;

Figure 3 shows a side cut-away view of an apparatus for producing pure silicon in accordance with an embodiment of the present invention;

Figures 4(a) and 4(b) show an EDX chart and corresponding SEM image of a first sample taken of an alloy containing pure silicon after the first electrolysis in the first crucible;

Figures 5(a) and 5(b) show an EDX chart and corresponding SEM image of a second sample taken of an alloy containing pure silicon after the first electrolysis in the first crucible;

Figures 6(a) and 6(b) show an EDX chart and corresponding SEM image of a third sample taken of an alloy containing pure silicon after the first electrolysis in the first crucible;

Figures 7(a) and 7(b) show an EDX chart and corresponding SEM image of a fourth sample taken of an alloy containing pure silicon after the first electrolysis in the first crucible;

Figure 8 shows EDX data and a corresponding SEM image of a sample of pure silicon which has naturally segregated from the alloy transferred from the first crucible into the second crucible in accordance with embodiments of the present invention;

Figure 9 shows EDX data and a corresponding SEM image of a sample of nano-sized pure silicon which has segregated from the alloy in the second crucible during a secondary electrolysis involving use of a 10%hydrochloric acid (HCI) electrolyte solution in accordance with embodiments of the present invention;

Figure 10 shows EDX data and a corresponding SEM image of a sample of nano-sized pure silicon which has segregated from the alloy in the second crucible during a secondary electrolysis involving use of a 20%hydrochloric acid (HCI) electrolyte solution in accordance with embodiments of the present invention;

Figure 11 shows a further EDX data and a corresponding SEM image of a further sample of nano-sized pure silicon which has segregated from the alloy in the second crucible during a secondary electrolysis in accordance with embodiments of the present invention;

Figure 12 shows an amorphous tape casted from an alloy remaining in the second crucible after natural segregation of some of the pure silicon particles in the alloy in accordance with embodiments of the present invention; and

Figure 13 shows testing parameters and test result data observed in producing an alloy containing pure silicon in the first crucible in accordance with embodiments of the present invention described herein when a direct heat furnace and induction furnace are variably used in heating the electrolyte during the first electrolysis.

Preferred Embodiments of the Invention

[0070] Preferred embodiments of the present invention will now be described below with reference to the accompanying drawings.

[0071] Figures 1 and 2 depict flowcharts of method steps in accordance with embodiments of the for producing pure silicon. In embodiments herein described, the term "pure silicon" refers to solar-grade silicon. An apparatus (1 ) which is used in performing the method steps depicted in Figs. 1 and 2 is shown in Fig. 3 and includes a first crucible (2) for receiving an electrolyte, a crucible lining (3) arranged within the first crucible (2) which separates the electrolyte from an inner peripheral wall (2a) of the first crucible (2), a heat source for heating the first crucible (2), an electrolysis device for applying electrolysis to the electrolyte (4) after the electrolyte (4) has been melted by the heat source, and a device for stirring the molten electrolyte (4) during electrolysis. Pure silicon produced by electrolysis forms an alloy with the anode (5). The pure silicon can thereafter be extracted from the alloy through use of a segregation apparatus and processes as will be described in greater detail below.

[0072] The electrolyte used in embodiments described herein comprise approximately 87% cryolite particles, 10% calcium oxide particles and 3% quartz particles by weight of the electrolyte (4). Before being deposited into the first crucible (2), the electrolyte (4) is manufactured by melting together the cryolite, calcium oxide and quartz particles at a temperature of 1200°C and then allowing the melted substance to solidify. The resulting density of this electrolyte (4) is approximately 3g/cm³.

[0073] The first crucible (2) is formed from a carbon material and has an internal recess (2c) for receiving the electrolyte (4). The recess (2c) is cylindrically-shaped and is defined by an inner peripheral wall (2a) and a base (2b). The first crucible (2) and internal recess (2c) need not be cylindrically-shaped in alternative embodiments. The first crucible (2) can alternatively be formed from materials such as silicon nitrate or silicon carbide material. Whichever material is used, it is desirable that the first crucible (2) material be able to generate heat if placed within an induction furnace, or, to conduct heat in a relatively efficient manner if placed in a direct heating furnace.

[0074] The electrolysis device includes an anode (5) and a cathode (7) which are connected to positive and negative terminals of a power supply (not shown). When the cathode (7) and anode (5) are placed in contact with the molten electrolyte (4) and a potential difference is generated between the anode (5) and cathode (7), the molten electrolyte (4) becomes subject to electrolysis thereby resulting in production of pure silicon.

[0075] The anode (5) includes an alloy of copper and approximately 3% pure silicon particles by weight of the alloy. The alloy is initially formed by melting the copper and combining the approximately 3% pure silicon particles at a temperature of approximately 1200°C. The inclusion of the 3% pure silicon particles in the alloy anode assists in setting the melting temperature of the alloy at a temperature which is applied during electrolysis. Although it is conceivable that more than 3% per weight of pure silicon could be initially combined with the copper to form the alloy anode, it is considered that this amount is a suitable minimum level in setting a suitable melting point.

[0076] The cathode (7) includes a carbon rod which is formed by pressed purified carbon powder. The carbon powder is purified before pressing by applying an acid wash and chlorine flushing to remove any impurities in the carbon powder. The carbon rod is controllably positionable and only lowered into the crucible recess into contact with the electrolyte (4) after the electrolyte (4) has been heated to form the molten electrolyte (4). In large-scale production, positioning of the carbon cathode (7) would be actuated by any automated mechanical positioning system known to persons skilled in the art. In the course of testing embodiments described herein, the carbon rod was lowered manually into contact with the molten electrolyte.

[0077] The crucible lining (3) is a cylindrical tube-shaped configuration which fits snugly within the first crucible recess. The crucible lining (3) complements and sits flush against the inner peripheral wall (2a) of the first crucible recess (2c). Accordingly, in use, the crucible lining (3) provides a barrier for separating the electrolyte (4) in the recess (2c) from the inner peripheral wall (2a) of the first crucible recess (2c). Notably, the presence of the crucible lining (3) assists in preventing electrolyte (4) from being absorbed into the first crucible wall (2a) which would otherwise decrease efficiency in the electrolysis process. Additionally, because the crucible lining (3) assists in blocking absorption of the electrolyte (4) into the first crucible wall (2a), this results in more electrolyte (4) being directed towards the alloy anode to further improve efficiency of the electrolysis process.

[0078] In this embodiment the crucible lining (3) is formed from quartz. As the quartz lining (3) is gradually corroded by the electrolyte (4) during electrolysis, this creates a time limitation upon the duration at which electrolysis can occur, and hence, the total amount of time which may be utilised in production of pure silicon via electrolysis. In seeking to prolong the duration of electrolysis, other less corrosive materials such as calcium oxide, magnesium fluoride, and sodium fluoride could be used in place of quartz. If a quartz material is used as the crucible lining (3), it can conveniently provide a suitable amount of additional quartz particles necessary to maintain the proportion of quartz particles in the molten electrolyte (4) at a predetermined level throughout the duration of electrolysis.

[0079] Yet alternatively pure silicon could be used to form the crucible lining (3) as this material does not tend to melt at temperatures applied in the electrolysis process, and, it does not tend to corrode due to interaction with the electrolyte (4). As a pure silicon crucible lining (3) does note tend to corrode, the selected thickness of the pure silicon crucible lining (3) is a less critical consideration than when a corrodible crucible lining (3) such as a quartz crucible lining (3) is used. Accordingly, in large scale production of pure silicon it is envisaged that the use of a pure silicon crucible lining (3) would be particularly advantageous because it can be reused to save ongoing costs of production. Also, in practical terms, the use of a pure silicon crucible lining (3) would assist in alleviating the practical complexities associated with use of a corrodible crucible lining (3) in which case a new crucible lining (3) would need to be regularly re-inserted into the first crucible (2). During testing of embodiments of the present invention, a quartz crucible of approximately 9.5 cm diameter was used. [0080] Alternatively and/or additionally it is also possible to create a natural crucible lining (3) within the first crucible (2) by suitably regulating the temperature at regions within the first crucible (2). For instance this could be implemented by generating a suitable temperature gradient whereby the temperature at the cathode (7) could be set relatively higher than the electrolyte situated adjacent the inner peripheral wall (2a) of the first crucible (2). Electric arc heating would be a particularly well-suited to generating the suitable temperature gradient due to relatively high temperatures arising at the cathode (7) relative to the electrolyte adjacent the inner peripheral wall of the first crucible (2). If the temperature of the cathode (7) were for example set at 980°C and the temperature of the electrolyte (4) adjacent the inner peripheral wall (2a) of the first crucible set at 900°C or lower, this would allow solidification of a natural crucible lining (3) adjacent the inner peripheral wall (2a) of the first crucible (2) whilst the remaining electrolyte (4) inwardly of the first crucible (2) would remain in molten form by virtue of the cathode (7) temperature. The creation of a natural crucible lining (3) is advantageous in that it obviates the need to provide a standalone crucible lining (3) thereby alleviating production costs and process implementation complexities.

[0081] In testing of embodiments described herein, a direct heat furnace was used as the primary heat source for heating the first crucible (2), the electrolyte (4), and, the alloy within the first crucible (2). However, it is contemplated that electric arc heating could be used as an alternative heat source in alternative embodiments whereby electrical resistance in the electrolyte medium between the anode (5) and cathode (7) gives rise to heat being generated. It would be readily understood that the further apart the anode (5) and cathode (7) are positioned, the higher the resistance that will be generated and hence the greater the amount of heat that will be transferred to the electrolyte (4) in the first crucible (2). Alternatively and/or additionally, an induction furnace could be used to provide induction heating.

[0082] The stirring device is used to constantly stir the molten electrolyte (4) during electrolysis. Stirring of the molten electrolyte (4) assists in both generating ion-flow in the electrolyte (4), and, increasing the contact between the electrolyte (4) and the molten alloy anode (5). Conveniently, the use of an induction furnace would inherently provide a stirring effect within the molten electrolyte during electrolysis. Accordingly, an induction furnace could be utilised both as a secondary heat source for regulating temperature, but also as the mechanism for stirring the molten electrolyte (4) during electrolysis. This would assist in alleviating costs incurred in acquiring a separate specialised stirring equipment. Furthermore, as the stirring provided by the induction furnace is due to electromagnetic force rather than direct mechanical interaction with the molten electrolyte (4), the time and cost required to repair a mechanical stirring devices may be alleviated. The induction furnace could be configured to apply current pulsing to stir the molten electrolyte (4). Of course, it is possible to utilise a mechanical stirrer in other embodiments of the present invention if required.

[0083] In alternative embodiments, a specialised magnetic stirring device could be used to magnetically stir the alloy in the first crucible (2).

[0084] A method of using the above-described apparatus to produce pure silicon will now be described in accordance with embodiments of the present invention.

[0085] Firstly, the quartz crucible lining (3) is fitted inside of the crucible recess by sliding the lining into the recess. This step is represented by block (100) in Fig. 1. The anode alloy (5) is thereafter deposited inside the crucible recess (2c) such that it sits in contact with the base of the first crucible (2). The first crucible (2) is then heated by the direct heat furnace at a temperature of between approximately 950- 980°C so as to melt the alloy. This step is represented by block (110) in Fig. 1.

[0086] As soon as the alloy (5) has melted, the solid electrolyte (4) is deposited into the first crucible recess (2c) on top of the melted alloy (5) and the first crucible (2) is further heated at a temperature of at least 900°C to melt the electrolyte into a molten electrolyte (4). These steps are represented by blocks (120) and (130) in Fig. 1.

[0087] Thereafter, electrolysis of the molten electrolyte (4) is commenced by lowering the carbon rod into contact with the molten electrolyte (4). This step is represented by block (140) in Fig. 1. As the cathode (7) is electrically connected directly to a negative terminal of the power supply, and, the alloy anode is electrically connected to a positive terminal of the power supply via the first crucible (2) (which is itself a conductive material) the potential difference between anode and cathode (7) facilitate electrolysis.

[0088] During testing of embodiments herein described, voltages in a range of 6-8V were applied across the anode (5) and cathode (7) which resulted in currents of between approximately 40-60A flowing between the anode (5) and cathode (7) via the molten electrolyte medium. The molten electrolyte (4) being contained in a quartz crucible of approximately 9.5 cm diameter and exposed to a current density of approximately 1 A/cm² across an approximate electrolyte surface area of 70.8800938 cm².

[0089] It should be noted that if the current density is set too high, this may result in damage to the crucible lining (3) and/or the first crucible (2). It would be understood by a person skilled in the art that variation in the dimensions of the first crucible (2), the magnitude of the current density applied and the surface of the electrolyte will affect the size of the yield of pure silicon produced in accordance with embodiments described herein. The yield can be generally approximated in accordance with the following formula:

YIELD = Current (A) x [Electrolysis Constant (0.262g/A h)] x [Hours of Electrolysis (h)]u

[0090] The molten electrolyte (4) is maintained at a temperature between approximately 900-1000°C to prevent solidification of the molten electrolyte (4) during electrolysis. Generally, when the molten electrolyte (4) is maintained at a relatively higher temperature during electrolysis, the efficiency of pure silicon production is improved. However certain limitations regarding the selected temperature should be noted. Firstly, it has been found that during testing of embodiments herein described, maintaining the temperature of the molten electrolyte (4) at a temperature of approximately 980°C during electrolysis, produces particularly desirable results. Temperatures above 980°C tend to cause an increase in evaporation and viscosity of the molten electrolyte (4) which impedes efficiency of pure silicon production and which may ultimately result in halted of electrolysis. Temperatures at or below 980°C will not tend to cause increases in evaporation and viscosity of the molten electrolyte (4) however the temperature should not drop below 900°C as the molten electrolyte (4) will solidify below this temperature.

[0091] As electrolysis takes place, the molten electrolyte (4) is stirred to increase flux of pure silicon particles produced during the electrolysis, into contact with the alloy anode (5). During testing, automated mechanical stirring was employed. However, an induction furnace could be conveniently used to magnetically stir the molten electrolyte (4) by applying current pulsing to the molten electrolyte (4). This step is represented by block (150) in Fig. 1.

[0092] During electrolysis, the proportion of quartz particles in the electrolyte (4) should be maintained at approximately 3% by weight of the electrolyte (4). To achieve this requirement, a sensor is used to periodically measure the quartz particles in the electrolyte (4) and a dispensing means is used to controllably dispense additional amounts of quartz particles into the molten electrolyte (4) to compensate for any depletion as required. As mentioned above, if a quartz material is used as the crucible lining (3) it may be feasible to utilise the quartz particles in the lining to compensate for depletion in quartz particles within the molten electrolyte (4) during electrolysis thereby maintaining the proportion of required quartz particles. This step is represented by block (160) in Fig. 1.

[0093] The pure silicon (6) which forms an alloy with the anode (5) by use of the above embodiment is shown in Figs. 5 and 6. The pure silicon (6) is able to be segregated from the alloy (5) by use of segregation techniques.

[0094] Electrolysis in the first crucible (2) will cease, after a limited timeframe, when the solubility limit of pure silicon in the alloy is reached. This step is represented by block (170) in Fig. 1. It has been found that during testing of embodiments of the present invention, when the alloy (5) is heated at a temperature between approximately 950-980°C, the pure silicon (6) is no longer soluble with the alloy (5) when the pure silicon (6) in the alloy (5) reaches approximately 25% by weight of the alloy (5). The time taken for the solubility limit to be reached will depend upon several factors including the surface area of the molten electrolyte (4) undergoing electrolysis. However, in testing of embodiment described herein, this solubility limit was found to be reached at around 8 hours. In terms of the yield and degree of purity of pure silicon (6) produced in accordance with the embodiments herein described, this would be understood to represent a considerable improvement in efficiency over existing production methods.

[0095] In this embodiment, with reference to Fig. 2, segregation of pure silicon from the alloy is thereafter commenced by first transferring the molten alloy (5) into a second crucible (not shown) by use of a suction device or any other suitable mechanical extraction means. The second crucible can be made from any material suitable for exposure to temperatures between approximately 800-1000°C. The material used to form the second crucible should however be inert with respect to the alloy and/or molten salts - that is, it should not chemically react with the alloy or any other molten salts. This step is represented by block (200) in Fig. 2.

[0096] The molten alloy is maintained at a temperature of between approximately 800-850°C in the second crucible whereby some of the pure silicon (6) within the molten alloy (5) will tend to naturally segregate from the alloy (5) as a result of thermodynamics. The pure silicon (6), which is of lower density than copper, naturally floats to the top of the molten alloy (5). This step is represented by block (210) in Fig. 2. During testing of embodiments of the present invention it has been found that approximately 11% pure silicon (6) particles by weight of the alloy (5) will float to the top of the melt as solid pure silicon (6). The now floating pure silicon (6) is able to be re-melted into ingots.

[0097] This form of naturally segregated pure silicon (6) has been found during testing to be suitable for solar-cell grade applications and is expected to provide at least around 18% efficiency which is consistent with the performance of conventionally produced solar-cell grade poly-silicon. Molten salts are used to cover the molten alloy (5) in the second crucible to alleviate the now floating solid pure silicon (6) from re-oxidising. Electronic grade silicon may also be produced via this method after several passes of zone refining is applied.

[0098] In certain embodiments the alloy remaining in the second crucible may be reintroduced back into the first crucible when approximately 11 % pure silicon (6) by weight of the molten alloy has naturally segregated from the alloy in the second crucible. The reintroduced molten alloy will sink to the bottom of the first crucible (2) and contribute further to the electrolysis process.

[0099] Alternatively, instead of reintroducing the remaining alloy in the second crucible back into the first crucible when the predetermined percentage of pure silicon particles has segregated from the alloy in the second crucible, the alloy remaining in the second crucible could be cast or extruded into an amorphous tape, or, mechanically grinded or milled into a powder of micron to nano sized alloy particles. It would be appreciated by a person skilled in the art that mechanical milling of the alloy has a greater tendency to introduce significant amount of impurities. Testing of embodiments of the present invention to date have involved mechanical grinding of alloys in the second crucible instead of tape casting. This step is represented by block (220) in Fig. 2.

[0100] The process and apparatus used in the casting of the amorphous tape can be configured to control the microstructure of the nano-sized pure silicon particles in the tape itself depending upon the rate of cooling during the tape casting. The nano- sized pure silicon particles which are thereafter able to be segregated from the tape in accordance with embodiments described herein could be in a range approximately between 10nm-60nm. Figure 12 shows an amorphous tape -which has been cast from the alloy.

[0101] Thereafter, a secondary electrolysis is applied to the tape or the powder after submerging the tape or powder in an electrolyte solution. In the embodiments described herein, electrolyte solutions having 10% hydrochloric acid (HCI) and 20% hydrochloric acid (HCI) were each used on different occasions with the results of these variations being indicated in Figs. 9 and 10 respectively. The acidity of the electrolyte solution is regularly replenished during the secondary electrolysis by pumping HCI gas into the electrolyte solution to maintain suitable pH and Cl^' levels. It would be appreciated by a person skilled in the art that in alternative embodiments, the alloy could be submerged in other electrolyte solutions including dehydrated acetic acid, iodine solutions (i.e. potassium iodine solution), hydrazoic acid (HN3), acetone, concentrated alcohol or combinations thereof. This step is represented by block (230) in Fig. 2. [0102] A current of less than approximately 1A is applied during the secondary electrolysis to suitably remove the copper from the alloy. After the secondary electrolysis is applied, the electrolyte solution contains Cu/Cu+/Cu++ and nano-sized pure silicon particles. A centrifuge device is then used to separate the nano-sized pure silicon particles from the electrolyte solution by way of centrifugal motion. This step is represented by block (240) in Fig. 2. It is possible in alternative embodiments to apply a current of greater than 1A during the secondary electrolysis however this may result in oxidation of the silicon. If that is the case, then an acid such as HF (hydrofluoric acid) could be used to melt the oxidized layer of silicon (quartz) to obtain nano-silicon.

[0103] As the nano-sized pure silicon particles have a greater tendency to react with oxygen, the nano-sized pure silicon particles are stored in a substance such as concentrated alcohol to alleviate reaction with free oxygen. This step is represented by block (250) in Fig. 2.

[0104] Copper which is extracted from the casted alloy tape or powder after the segregation process can be reintroduced back in to the first crucible (2) to assist in the electrolysis process within the first crucible (2). As would be appreciated by a person skilled in the art, this may be considered the more efficient manner in saving energy since the already segregated molten alloy is at 800-850°C and would merely require 100-150°C worth of energy to continue electrolysis in the first crucible (2).

[0105] In other embodiments, copper could be removed from the alloy in the second crucible by flushing the tape or powder with HCI gas or chlorine gas in an enclosed area that is oxygen free to allow the tape or powder to react with the HCI gas or chlorine gas. CuCI₂ will then have to be removed via mechanical methods or rinsing with suitable solutions in which CuCI₂ is soluble in. Nano-sized pure silicon particles can then be removed. CuCI₂ is paramagnetic as a person skilled in the art would readily appreciate. Accordingly, a magnetic field could be applied to the powder that contains CuCI₂ to remove CuCI₂ from the powder whilst alleviating introduction of contaminants if it were to be rinsed by oxygen containing solutions. Advantageously, CuCI₂ which is formed as a result of flushing the tape or powder with HCI gas or chlorine gas would readily dissolve into any concentrated alcohol which is used to alleviate re-oxidation of the nano-sized pure silicon particles. [0106] It would be further appreciated by a person skilled in the art that in yet alternative embodiments, the above process and apparatus for segregating pure silicon from the alloy in the second crucible could be similarly performed directly upon the alloy in the first crucible without first removing the alloy in the first crucible (2) into a second crucible and without first allowing natural segregation of pure silicon from the alloy. Hence, the alloy in the first crucible (2) containing 25% pure silicon particle by weight of the alloy could be exposed to the above-described segregation apparatus and process by forming the alloy into a tape or powder and applying electrolysis to the tape or powder before separating formed nano-sized pure silicon particles from the electrolyte solution.

[0107] It would be further understood by a person skilled in the art that the above- described apparatus and method for segregating pure silicon from an alloy need not necessarily be applied to a pure silicon containing alloy formed in accordance with embodiments described herein and could be applied to alloys produced in accordance with alternative apparatuses and methods.

[0108] Figures 4(a)-4(b), 5(a)-5(b), 6(a)-6(b) and 7(a)-7(b) show EDX data and corresponding SEM images for 4 different sample regions of an alloy produced in the first crucible after the first electrolysis in accordance with embodiments of the present invention described herein. It would be understood by a person skilled in the art that the variation in proportion of pure silicon to copper in the alloy for each analysed sample varies as a result of the location upon the alloy at which the sample reading has been taken. For instance, Figs. 5(a) and 5(b) which indicate a relatively high component of pure silicon (i.e. 100%) compared to copper (negligible) has been taken on a region of the alloy which is mostly pure silicon. In contrast Figs. 4(a) and 4(b) indicate a relatively lower component of pure silicon in the alloy (i.e. 68.83%) due to the sample reading being taken at or near an interface between silicon and copper in the alloy.

[0109] Figure 8 shows EDX data and a corresponding SEM image of pure silicon which has naturally segregated from the alloy in the second crucible due to different densities between the pure silicon and the copper in the alloy. The pure silicon shown in Fig. 8 is suitable for melting into ingots. [0110] Figures 9, 10 and 11 show EDX data and a corresponding SEM images of nano-sized pure silicon particles which have been produced and segregated from alloys following the secondary electrolysis and processing described herein. The nano-sized pure silicon particles shown in Fig. 9 involved the use of an electrolyte solution having 10% hydrochloric acid (HCI) whilst the nano-sized particles shown in Fig. 10 involved the use of an electrolyte solution having 20% hydrochloric acid (HCI) during the secondary electrolysis. The presence of aluminium indicated in the EDX data is introduced during the mechanical grinding process of the alloy and can be substantially eliminated by use of higher precision grinding of the alloy in future experimentation. The oxygen component is also able to be substantially eliminated in further experimentation by storing the segregated nano-sized pure silicon particles in concentrated alcohol to alleviate re-oxidation in to quartz. Accordingly, it is considered that purity substantially above 99% silicon is achievable in view of the above.

[0111] Figure 13 shows data produced during testing of embodiments of the present invention in producing pure silicon. An average efficiency of approximately 71% and 75% is achieved using direct heat furnacing and induction furnacing during the first electrolysis in the first crucible respectively. The fourth columns ("g (before)") in Fig. 13 indicates the amount of pure silicon in the alloy anode before the first electrolysis commences whilst the fifth columns ("g (after)") indicates the pure silicon in the alloy after the first electrolysis in the first crucible (2) has taken place. The efficiency is able to be determined by the net gain in pure silicon against energy expended in the process.

[0112] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described without departing from the scope of the invention. All such variations and modification which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope of the invention as broadly hereinbefore described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps and features, referred or indicated in the specification, individually or collectively, and any and all combinations of any two or more of said steps or features. [0113] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge.

Claims

What is claimed is:

1. A method of producing pure silicon from an electrolyte wherein the method includes the steps of:

wherein the molten electrolyte is stirred as electrolysis is being applied and pure silicon produced as a result of the electrolysis is soluble with the anode to form an alloy.

2. A method as claimed in claim 1 wherein the electrolyte comprises cryolite, calcium oxide particles and quartz particles.

3. A method as claimed in claim 2 wherein the electrolyte comprises approximately between 82-94% cryolite particles by weight of the electrolyte.

4. A method as claimed in claims 2 or 3 wherein the electrolyte comprises approximately between 3-15% calcium oxide particles by weight of the electrolyte.

5. A method as claimed in any one of the claims 2 to 4 wherein the electrolyte comprises approximately 3% quartz particles by weight of the electrolyte.

6. A method as claimed in any one of claims 2 to 5 wherein the electrolyte comprises approximately 87% cryolite particles, 10% calcium oxide particles and 3% quartz particles by weight of the electrolyte.

7. A method as claimed in any one of claims 2 to 6 including a step of controllably adding quartz particles to the electrolyte during electrolysis to substantially maintain approximately 3% quartz particles in the electrolyte by weight of the electrolyte.

8. A method as claimed in any one of the preceding claims wherein the first crucible includes at least one of a carbon, silicon nitrate and silicon carbide material.

9. A method as claimed in any one of claims 1 to 8 wherein the first crucible includes a recess defined by an inner peripheral wall and a base for receiving the electrolyte.

10. A method as claimed in claim 9 including the step of arranging a crucible lining inside the first crucible recess between the first crucible and the electrolyte.

11. A method as claimed in claim 10 wherein the crucible lining is contoured to substantially complement the inner peripheral wall of the crucible.

12. A method as claimed in claims 10 or 11 wherein the crucible lining includes at least one of a quartz, calcium oxide, magnesium fluoride, sodium fluoride and silicon material.

13. A method as claimed in any one of claims 10 to 12 wherein the crucible lining is formed from the molten electrolyte by generating a temperature gradient within the molten electrolyte wherein a portion of the molten electrolyte is solidified adjacent the inner peripheral wall of the first crucible.

14. A method as claimed in claim 13 wherein arc furnacing is used to create the temperature gradient between the cathode and molten electrolyte adjacent the inner peripheral wall of the first crucible.

15. A method as claimed in any one of the preceding claims wherein the electrolyte is heated using at least one of an arc furnace and an induction furnace.

16. A method as claimed in any one of the preceding claims wherein the molten electrolyte is stirred using at least one of an induction furnace to magnetically stir the molten electrolyte, a magnetic stirring device for pulse stirring the molten electrolyte, and a mechanical stirrer.

17. A method as claimed in any one of the preceding claims wherein the anode includes at least one of a copper, gold, silver, zinc and a magnesium material.

18. A method as claimed in claim 17 wherein the anode includes an alloy of at least one of copper and pure silicon, said pure silicon comprising approximately 3% by weight of the alloy.

19. A method as claimed in claim 18 wherein prior to step (i) of claim 1 , the alloy is positioned in the first crucible adjacent the base of the first crucible and melted in the first crucible whereby said electrolyte is able to be thereafter deposited into the first crucible on top of the melted alloy in readiness for step (i) of claim 1 to be performed.

20. A method as claimed in claim 19 wherein the alloy is melted at a temperature of between approximately 950-980°C.

21. A method as claimed in any one of the preceding claims wherein step (i) of claim 1 includes heating the electrolyte in the first crucible to a temperature of at least approximately 900°C in order to form the molten electrolyte.

22. A method as claimed in any one of the preceding claims wherein during step (ii) of claim 1, the molten electrolyte is maintained at a temperature whereby the molten electrolyte does not solidify.

23. A method as claimed in claim 22 wherein the temperature of the molten electrolyte is maintained between approximately 900-1000°C to prevent solidification of the molten electrolyte.

24. A method as claimed in claims 22 or 23 wherein the temperature of the molten electrolyte is maintained at approximately 980°C to prevent solidification of the molten electrolyte.

25. A method as claimed in any one of the preceding claims wherein the molten electrolyte is exposed to a current density of approximately between 0.1 A/cm² to 2.A/cm² in the first crucible when electrolysis is applied.

26. A method as claimed in any one of the preceding claims wherein the cathode includes at least one of a carbon, copper, platinum and a tungsten material.

27. A method as claimed in any one of the preceding claims wherein the cathode is positioned into the first crucible after the electrolyte has been heated to form the molten electrolyte whereby the cathode is in electrical/ionic communication with the molten electrolyte.

28. A method as claimed in any one of the preceding claims including a step of segregating the pure silicon from copper in the alloy.

29. A method as claimed in claim 28 wherein the step of segregating the pure silicon from the alloy is performed when pure silicon produced in the first crucible as a result of electrolysis is no longer soluble with the alloy.

30. A method as claimed in claim 29 wherein if the alloy is at a temperature of between approximately 950-980°C, the pure silicon is no longer soluble with the alloy when the pure silicon in the alloy is approximately 25% per weight of the alloy.

31. A method as claimed in any one of claims 28 to 30 wherein the step of segregating the pure silicon from the alloy includes adjusting the temperature of the alloy to between approximately 800-850°C whereby pure silicon is able to naturally segregate from the alloy.

32. A method as claimed in claim 31 wherein before adjusting the temperature of the alloy to between approximately 800-850°C, the alloy is transferred from the first crucible into a second crucible, said second crucible including a material which is inert with respect to the alloy and/or molten salts.

33. A method as claimed in claim 32 wherein the alloy in the second crucible is reintroduced back into the first crucible when a predetermined percentage of pure silicon particles by weight of the alloy has naturally segregated from the alloy.

34. A method as claimed in claim 33 wherein the predetermined percentage of pure silicon particles by weight of the alloy includes approximately 11% of pure silicon particles by weight of the alloy.

35. A method as claimed in claims 33 or 34 wherein instead of reintroducing the alloy in the second crucible back into the first crucible when the predetermined percentage of pure silicon particles has naturally segregated from the alloy in the second crucible, the following steps are performed:

(i) the alloy in the second crucible is formed into at least one of a tape and a powder; and

(ii) a secondary electrolysis is applied to the tape or powder;

whereby pure silicon particles are able to be further segregated from the alloy in the form of nano-sized pure silicon particles.

36. A method as claimed in claim 35 wherein the tape is formed by at least one of casting and extruding the alloy.

37. A method as claimed in claim 35 wherein the powder is formed by at least one of mechanically grinding and milling the alloy in a controlled environment.

38. A method as claimed in any one of claims 35 to 37 wherein the step of applying the secondary electrolysis includes submerging the tape or powder in an electrolyte solution.

39. A method as claimed in claim 38 wherein the electrolyte solution includes at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions, hydrazoic acid (HN3), acetone, concentrated alcohol and a combination thereof.

40. A method as claimed in claims 39 wherein an acidity of the electrolyte solution is replenished during the secondary electrolysis.

41. A method as claimed in any one of claims 35 to 40 wherein a current of less than approximately 1 A is applied during the secondary electrolysis.

42. A method as claimed in any one of claims 38 to 41 wherein after the electrolysis has been performed, the electrolyte solution containing the nano-sized pure silicon particles is further processed to separate the nano-sized pure silicon particles from the electrolyte solution.

43. A method as claimed in claim 42 wherein the further processing includes centrifugally separating the nano-sized pure silicon particles from the electrolyte solution.

44. A method as claimed in claims 42 to 43 wherein the separated nano-sized pure silicon particles are thereafter stored in a substance suitable for alleviating reaction with free oxygen.

45. A method as claimed in claim 44 wherein the substance includes concentrated alcohol.

46. A method as claimed in any one of claims 28 to 30, wherein segregation is performed directly upon the alloy formed in the first crucible after electrolysis in accordance with any one of the method steps of claims 35 to 45.

47. An apparatus for producing pure silicon from an electrolyte including: a first crucible for receiving the electrolyte;

a stirring device for stirring the molten electrolyte when electrolysis is being applied to the molten electrolyte whereby pure silicon produced as a result of the electrolysis is soluble with the anode to form an alloy.

48. An apparatus as claimed in claim 47 wherein the electrolyte comprises cryolite, calcium oxide particles and quartz particles.

49. An apparatus as claimed in claim 48 wherein the electrolyte comprises approximately between 82-94% cryolite particles by weight of the electrolyte.

50. An apparatus as claimed in claims 48 or 49 wherein the electrolyte comprises approximately between 3-15% calcium oxide particles by weight of the electrolyte.

51. An apparatus as claimed in any one of claims 48 to 50 wherein the electrolyte comprises approximately 3% quartz particles by weight of the electrolyte.

52. An apparatus as claimed in any one of claims 48 to 51 wherein the electrolyte comprises approximately 87% cryolite particles, 10% calcium oxide particles and 3% quartz particles by weight of the electrolyte.

53. An apparatus as claimed in any one of claims 48 to 52 including a dispenser for dispensing quartz particles in to the electrolyte during electrolysis to substantially maintain approximately 3% quartz particles in the electrolyte by weight of the electrolyte.

54. An apparatus as claimed in any one of claims 47 to 53 wherein the first crucible includes at least one of a carbon, silicon nitrate and a silicon carbide material.

55. An apparatus as claimed in any one of claims 47 to 54 wherein the first crucible includes a recess defined by an inner peripheral wall and a base for receiving the electrolyte.

56. An apparatus as claimed in claim 55 including a crucible lining arranged inside of the recess between the first crucible and the electrolyte.

57. An apparatus as claimed in claim 56 wherein the crucible lining is contoured to substantially complement the inner peripheral wall of the first crucible.

58. An apparatus as claimed in claims 56 or 57 wherein the crucible lining includes at least one of a quartz, calcium oxide, magnesium fluoride, sodium fluoride and silicon material.

59. An apparatus as claimed in any one of claims 56 to 58 wherein the first crucible includes a crucible lining formed from solidification of a portion of the molten electrolyte as a result of a temperature gradient being generated within the molten electrolyte.

60. An apparatus as claimed in claim 59 including an arc furnacing device for generating the temperature gradient between the cathode and molten electrolyte adjacent the inner peripheral wall of the first crucible.

61. An apparatus as claimed in any one of claims 47 to 60 wherein the heat source includes at least one of an arc furnace and an induction furnace.

62. An apparatus as claimed in any one of claims 47 to 61 wherein the stirring device includes at least one of an induction furnace for magnetically stirring the molten electrolyte, a magnetic stirring device for pulse stirring the molten electrolyte, and a mechanical stirrer.

63. An apparatus as claimed in any one of claims 47 to 62 wherein the anode includes at least one of a copper, gold , silver, zinc and a magnesium material.

64. An apparatus as claimed in claim 63 wherein the anode includes an alloy of copper and pure silicon, said pure silicon comprising approximately 3% by weight of the alloy.

65. An apparatus as claimed in claim 64 wherein the alloy is melted in the first crucible adjacent the base of the first crucible and the electrolyte is positioned on top of the alloy.

66. An apparatus as claimed in claim 65 wherein the heat source is adapted to melt the alloy at a temperature of between approximately 950-980°C.

67. An apparatus as claimed in any one of claims 47 to 66 wherein the heat source is adapted to heat the electrolyte in the first crucible to a temperature of at least approximately 900°C in order to form the molten electrolyte.

68. An apparatus as claimed in any one of claims 47 to 67 wherein during electrolysis of the molten electrolyte, the heat source is adapted to maintain the molten electrolyte at a temperature whereby the molten electrolyte does not solidify.

69. An apparatus as claimed in claim 68 wherein the heat source is adapted to maintain the temperature of the molten electrolyte at between approximately 900- 1000°C to prevent solidification of the molten electrolyte.

70. An apparatus as claimed in claims 68 or 69 wherein the heat source is adapted to maintain the temperature of the molten electrolyte at approximately 980°C to prevent solidification of the molten electrolyte.

71. An apparatus as claimed in any one of claims 47 to 70 wherein the molten electrolyte is exposed to a current density of approximately between 0.1 A/cm² to 2. OA/cm² in the first crucible when electrolysis is applied.

72. An apparatus as claimed in any one of claims 47 to 71 wherein the cathode includes at least one of a carbon, platinum, copper and a tungsten material.

73. An apparatus as claimed in any one of claims 47 to 72 wherein the cathode is adapted for positioning into the first crucible after the electrolyte has been heated to form the molten electrolyte whereby the cathode is positioned in electrical/ionic communication with the molten electrolyte.

74. An apparatus as claimed in any one of claims 47 to 73 including an apparatus for segregating pure silicon from the alloy.

75. An apparatus as claimed in claim 74 wherein the apparatus for segregating pure silicon from the alloy is adapted for segregating the pure silicon from the alloy when pure silicon produced in the first crucible as a result of electrolysis is no longer soluble with the alloy.

76. An apparatus as claimed in claim 75 wherein if the alloy is at a temperature of between approximately 950-980°C, the pure silicon is no longer soluble with the alloy when the pure silicon in the alloy is approximately 25% per weight of the alloy.

77. An apparatus as claimed in any one of claims 74 to 76 wherein the apparatus for segregating pure silicon from the alloy is adapted to adjust the temperature of the alloy to between approximately 800-850°C whereby pure silicon is able to naturally segregate from the alloy.

78. An apparatus as claimed in claim 77 wherein the apparatus for segregating pure silicon from the alloy is adapted for transferring the alloy in the first crucible into a second crucible before adjusting the temperature of the alloy to between approximately 800-850°C, said second crucible including a material which is inert with respect to the alloy and/or molten salts.

79. An apparatus as claimed in claim 78 wherein the apparatus for segregating pure silicon from the alloy is adapted for reintroducing the alloy in the second crucible back into the first crucible when a predetermined percentage of pure silicon particles by weight of the alloy has naturally segregated from the alloy in the second crucible.

80. An apparatus as claimed in claim 79 wherein the predetermined percentage of pure silicon particles by weight of the alloy includes approximately 11% of pure silicon particles by weight of the alloy.

81. An apparatus as claimed in any one of claims 74 to 80 wherein when after pure silicon has naturally segregated from the alloy, the apparatus for segregating pure silicon from the alloy is adapted for:

(i) forming the alloy in the second crucible into at least one of a tape and a powder; and

(ii) applying a secondary electrolysis to the tape or powder;

whereby pure silicon particles is able to be further segregated from the alloy in the form of nano-sized pure silicon particles.

82. An apparatus as claimed in claim 81 wherein the apparatus for segregating pure silicon from the alloy is adapted for forming the tape by at least one of casting and extruding the alloy.

83. An apparatus as claimed in claim 81 wherein the apparatus for segregating pure silicon from the alloy is adapted for forming the powder by at least one of mechanically grinding and milling the alloy in a controlled environment.

84. An apparatus as claimed in any one of claims 81 to 83 wherein the apparatus for segregating pure silicon from the alloy is adapted for submerging the tape or powder in an electrolyte solution during application of the secondary electrolysis.

85. An apparatus as claimed in claim 84 wherein the electrolyte solution includes at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions, hydrazoic acid (HN3), acetone, concentrated alcohol and a combination thereof.

86. An apparatus as claimed in claims 85 wherein the apparatus for segregating pure silicon from the alloy is adapted for replenishing an acidity of the electrolyte solution during application of the secondary electrolysis.

87. An apparatus as claimed in any one of claims 81 to 86 wherein the apparatus for segregating pure silicon from the alloy is adapted to apply a current of less than approximately 1 A during the secondary electrolysis.

88. An apparatus as claimed in any one of claims 84 to 87 wherein the apparatus for segregating pure silicon from the alloy is adapted for separating nano-sized pure silicon particles contained in the electrolyte solution from the electrolyte solution after the secondary electrolysis has been applied.

89. An apparatus as claimed in claim 88 wherein the apparatus for segregating pure silicon from the alloy is adapted for centrifugally separating the nano-sized pure silicon particles contained in the electrolyte solution from the electrolyte solution after the secondary electrolysis.

90. An apparatus as claimed in claims 88 or 89 wherein the apparatus for segregating pure silicon from the alloy is adapted for storing the separated nano- sized pure silicon particles in a substance which alleviates reaction with free oxygen.

91. An apparatus as claimed in claim 90 wherein the substance includes concentrated alcohol.

92. An apparatus as claimed in any one of claims 74 to 76, wherein the segregation is performed directly upon the alloy formed in the first crucible after electrolysis in accordance with any one of the method steps of claims 81 to 91.

93. A method of producing pure silicon from an electrolyte wherein the method includes the steps of:

wherein a crucible lining is arranged inside the first crucible to substantially separate the molten electrolyte from an inner peripheral wall of the first crucible as electrolysis is being applied and pure silicon produced as a result of the electrolysis is soluble with the anode to form an alloy.

94. A method as claimed in claim 93 wherein the electrolyte comprises cryolite, calcium oxide particles and quartz particles.

95. A method as claimed in claim 94 wherein the electrolyte comprises approximately between 82-94% cryolite particles by weight of the electrolyte.

96. A method as claimed in claims 94 or 95 wherein the electrolyte comprises approximately between 3-15% calcium oxide particles by weight of the electrolyte.

97. A method as claimed in any one of claims 94 to 96 wherein the electrolyte comprises approximately 3% quartz particles by weight of the electrolyte.

98. A method as claimed in any one of claims 94 to 97 wherein the electrolyte comprises approximately 87% cryolite particles, 10% calcium oxide particles and 3% quartz particles by weight of the electrolyte.

99. A method as claimed in any one of claims 94 to 98 including a step of controllably adding quartz particles to the electrolyte during electrolysis to substantially maintain approximately 3% quartz particles in the electrolyte by weight of the electrolyte.

100. A method as claimed in any one of claims 93 to 99 wherein the first crucible includes at least one of a carbon, silicon nitrate and silicon carbide material.

101. A method as claimed in any one of claims 93 to 100 wherein the first crucible includes a recess defined by the inner peripheral wall and a base for receiving the electrolyte.

102. A method as claimed in claim 101 wherein the crucible lining is contoured to substantially complement the inner peripheral wall of the first crucible.

103. A method as claimed in any one of claims 93 to 102 wherein the crucible lining includes at least one of a quartz, calcium oxide, magnesium fluoride, sodium fluoride and a silicon material.

104. A method as claimed in any one of claims 93 or 103 wherein the crucible lining is formed from the molten electrolyte by generating a temperature gradient within the molten electrolyte wherein a portion of the molten electrolyte is solidified adjacent the inner peripheral wall of the first crucible.

105. A method as claimed in claim 104 wherein arc furnacing is used to create the temperature gradient between the cathode and molten electrolyte adjacent the inner peripheral wall of the first crucible.

106. A method as claimed in any one of claims 93 to 105 wherein the electrolyte is heated using at least one of an arc furnace and an induction furnace.

107. A method as claimed in any one of claims 93 to 106 wherein the molten electrolyte is stirred as electrolysis is being applied to the molten electrolyte.

108. A method as claimed in claim 107 wherein the molten electrolyte is stirred using at least one of an induction furnace, a magnetic stirring device for pulse stirring the molten electrolyte, and a mechanical stirrer.

109. A method as claimed in any one of claims 93 to 108 wherein the anode includes at least one of a copper, gold , silver, zinc and a magnesium material.

110. A method as claimed in claim 109 wherein the anode includes an alloy of copper and pure silicon, said pure silicon comprising approximately 3% by weight of the alloy.

111. A method as claimed in claim 110 wherein prior to step (i) of claim 93, the alloy is positioned in the first crucible adjacent the base of the first crucible and melted in the first crucible whereby said electrolyte is able to be thereafter deposited into the first crucible on top of the melted alloy in readiness for step (i) of claim 93 to be performed.

112. A method as claimed in claim 111 wherein the alloy is melted at a temperature of between approximately 950-980°C.

113. A method as claimed in any one claims 93 to 112 wherein step (i) of claim 93 includes heating the electrolyte in the first crucible to a temperature of at least approximately 900°C in order to form the molten electrolyte.

114. A method as claimed in any one claims 93 to 113 wherein during step (ii) of claim 93, the molten electrolyte is maintained at a temperature whereby the molten electrolyte does not solidify.

115. A method as claimed in claim 114 wherein the temperature of the molten electrolyte is maintained between approximately 900-1000°C to prevent solidification of the molten electrolyte.

116. A method as claimed in claims 114 or 115 wherein the temperature of the molten electrolyte is maintained at approximately 980°C to prevent solidification of the molten electrolyte.

117. A method as claimed in any one of claims 93 to 116 wherein the molten electrolyte is exposed to a current density of approximately between 0.1 A/cm² to 2. OA/cm² in the first crucible when electrolysis is applied.

118. A method as claimed in any one of claims 93 to 117 wherein the cathode includes at least one of a carbon, copper, platinum and a tungsten material.

119. A method as claimed in any one of claims 93 to 1 8 wherein the cathode is positioned into the first crucible after the electrolyte has been heated to form the molten electrolyte whereby the cathode is in electrical/ionic communication with the molten electrolyte.

120. A method as claimed in any one of claims 93 to 119 including a step of segregating the pure silicon from copper in the alloy.

121. A method as claimed in claim 120 wherein the step of segregating the pure silicon from the alloy is performed when pure silicon produced in the first crucible as a result of electrolysis is no longer soluble with the alloy.

122. A method as claimed in claim 121 wherein if the alloy is at a temperature of between approximately 950-980°C, the pure silicon is no longer soluble with the alloy when the pure silicon in the alloy is approximately 25% per weight of the alloy.

123. A method as claimed in any one of claims 120 to 122 wherein the step of segregating the pure silicon from the alloy includes adjusting the temperature of the alloy to between approximately 800-850°C whereby pure silicon is able to naturally segregate from the alloy.

124. A method as claimed in claim 123 wherein before adjusting the temperature of the alloy to between approximately 800-850°C, the alloy is transferred into a second crucible, said second crucible including a material which is inert with respect to the alloy and/or molten salts.

125. A method as claimed in claim 124 wherein the alloy in the second crucible is reintroduced back into the first crucible when a predetermined percentage of pure silicon particles by weight of the alloy has naturally segregated from the alloy.

126. A method as claimed in claim 125 wherein the predetermined percentage of pure silicon particles by weight of the alloy includes approximately 11% of pure silicon particles by weight of the alloy.

127. A method as claimed in claims 125 or 126 wherein instead of reintroducing the alloy in the second crucible back into the first crucible when the predetermined percentage of pure silicon particles has naturally segregated from the alloy in the second crucible, the following steps are performed:

(ii) a secondary electrolysis is applied to the tape or powder;

128. A method as claimed in claim 127 wherein the tape is formed by at least one of casting arid extruding the alloy.

129. A method as claimed in claim 128 wherein the powder is formed by at least one of mechanically grinding and milling the alloy in a controlled environment.

130. A method as claimed in any one of claims 127 to 129 wherein the step of applying the secondary electrolysis includes submerging the tape or powder in an electrolyte solution.

131. A method as claimed in claim 130 wherein the electrolyte solution includes at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions, hydrazoic acid (HN3), acetone, concentrated alcohol and a combination thereof.

132. A method as claimed in claims 131 wherein an acidity of the electrolyte solution is replenished during the secondary electrolysis.

133. A method as claimed in any one of claims 127 to 132 wherein a current of less than approximately 1A is applied during the secondary electrolysis.

134. A method as claimed in any one of claims 130 to 133 wherein after the secondary electrolysis has been applied, the electrolyte solution containing the nano- sized pure silicon particles is further processed to separate the nano-sized pure silicon particles from the electrolyte solution.

135. A method as claimed in claim 134 wherein the further processing includes centrifugally separating the nano-sized pure silicon particles from the electrolyte solution.

136. A method as claimed in claims 134 or 135 wherein the separated nano-sized pure silicon particles are thereafter stored in a substance suitable for alleviating reaction with free oxygen.

137. A method as claimed in claim 136 wherein the substance includes concentrated alcohol.

138. A method as claimed in any one of claims 120 to 122, wherein segregation is performed directly upon the alloy formed in the first crucible after electrolysis in accordance with any one of the method steps of claims 127 to 137.

139. An apparatus for producing pure silicon from an electrolyte including:

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; and

wherein pure silicon produced as a result of the electrolysis is soluble with the anode to form an alloy.

140. An apparatus as claimed in claim 139 wherein the electrolyte comprises cryolite, calcium oxide particles and quartz particles.

141. An apparatus as claimed in claim 140 wherein the electrolyte comprises approximately between 82-94% cryolite particles by weight of the electrolyte.

142. An apparatus as claimed in claims 140 or 141 wherein the electrolyte comprises approximately between 3-15% calcium oxide particles by weight of the electrolyte.

143. An apparatus as claimed in any one of claims 140 to 142 wherein the electrolyte comprises approximately 3% quartz particles by weight of the electrolyte.

144. An apparatus as claimed in any one of claims 140 to 143 wherein the electrolyte comprises approximately 87% cryolite particles, 10% calcium oxide particles and 3% quartz particles by weight of the electrolyte.

145. An apparatus as claimed in any one of claims 140 to 143 including a dispenser for dispensing quartz particles in to the electrolyte during electrolysis to substantially maintain approximately 3% quartz particles in the electrolyte by weight of the electrolyte.

146. An apparatus as claimed in any one of claims 139 to 145 wherein the first crucible includes at least one of a carbon, silicon nitrate and silicon carbide material.

147. An apparatus as claimed in any one of claims 139 to 146 wherein the first crucible includes a recess defined by the inner peripheral wall and a base for receiving the electrolyte.

148. An apparatus as claimed in any one of claims 139 to 147 wherein the crucible lining is contoured to substantially complement the inner peripheral wall of the crucible.

149. An apparatus as claimed in any one of claims 139 or 148 wherein the crucible lining includes at least one of a quartz, calcium oxide, magnesium fluoride, sodium fluoride and silicon material.

150. An apparatus as claimed in any one of claims 139 to 149 wherein the first crucible includes a crucible lining formed from solidification of a portion of the molten electrolyte as a result of a temperature gradient being generated within the molten electrolyte.

151. A method as claimed in claim 150 including an arc furnacing device for generating the temperature gradient between the cathode and molten electrolyte adjacent the inner peripheral wall of the first crucible.

152. An apparatus as claimed in any one of claims 139 to 151 wherein the heat source includes at least one of an arc furnace and an induction furnace.

153. An apparatus as claimed in any one of claims 139 to 152 including a stirring device for stirring the molten electrolyte when electrolysis is being applied to the molten electrolyte.

154. An apparatus as claimed in claim 153 wherein the stirring device includes at least one of an induction furnace, a magnetic stirring device for pulse stirring the molten electrolyte, and a mechanical stirrer.

155. An apparatus as claimed in any one of claims 139 to 154 wherein the anode includes at least one of a copper, gold , silver, zinc and a magnesium material.

156. An apparatus as claimed in claim 155 wherein the anode includes an alloy of copper and pure silicon, said pure silicon comprising approximately 3% by weight of the alloy.

157. An apparatus as claimed in claim 156 wherein the alloy is melted in the first crucible adjacent the base of the first crucible and the electrolyte is positioned on top of the alloy.

158. An apparatus as claimed in claim 157 wherein the heat source is adapted to melt the alloy at a temperature of between approximately 950-980°C.

159. An apparatus as claimed in any one of claims 139 to 158 wherein the heat source is adapted to heat the electrolyte in the first crucible to a temperature of at least approximately 900°C in order to form the molten electrolyte.

160. An apparatus as claimed in any one of claims 139 to 159 wherein during electrolysis of the molten electrolyte, the heat source is adapted to maintain the molten electrolyte at a temperature whereby the molten electrolyte does not solidify.

161. An apparatus as claimed in claim 160 wherein the heat source is adapted to maintain the temperature of the molten electrolyte at between approximately 900- 1000°C to prevent solidification of the molten electrolyte.

162. An apparatus as claimed in claims 160 or 161 wherein the heat source is adapted to maintain the temperature of the molten electrolyte at approximately 980°C to prevent solidification of the molten electrolyte.

163. An apparatus as claimed in any one of claims 139 to 162 wherein the molten electrolyte is exposed to a current density of approximately between 0.1 A/cm² to 2. OA/cm² in the first crucible when electrolysis is applied.

164. An apparatus as claimed in any one of claims 139 to 163 wherein the cathode includes at least one of a carbon, copper, platinum and a tungsten material.

165. An apparatus as claimed in any one of claims 139 to 164 wherein the cathode is adapted for positioning into the first crucible after the electrolyte has been heated to form the molten electrolyte whereby the cathode is positioned in electrical/ionic communication with the molten electrolyte.

166. An apparatus as claimed in any one of claims 139 to 165 including a device for segregating pure silicon from copper in the alloy.

167. An apparatus as claimed in claim 166 wherein the apparatus for segregating pure silicon from the alloy is adapted for segregating the pure silicon from the alloy when pure silicon produced in the first crucible as a result of electrolysis is no longer soluble with the alloy.

168. An apparatus as claimed in claim 167 wherein if the alloy is at a temperature of between approximately 950-980°C, the pure silicon is no longer soluble with the alloy when the pure silicon in the alloy is approximately 25% per weight of the alloy.

169. An apparatus as claimed in any one of claims 166 to 168 wherein the apparatus for segregating pure silicon from the alloy is adapted to adjust the temperature of the alloy to between approximately 800-850°C whereby pure silicon is able to naturally segregate from the alloy.

170. An apparatus as claimed in claim 169 wherein the apparatus for segregating pure silicon from the alloy is adapted for transferring the alloy in the first crucible into a second crucible before adjusting the temperature of the alloy to between approximately 800-850°C, said second crucible including a material which is inert with respect to the alloy and/or molten salts.

171. An apparatus as claimed in claim 170 wherein the apparatus for segregating pure silicon from the alloy is adapted for reintroducing the alloy in the second crucible back into the first crucible when the predetermined percentage of pure silicon particles by weight of the alloy has naturally segregated from the alloy in the second crucible.

172. An apparatus as claimed in claim 171 wherein the predetermined percentage of pure silicon particles by weight of the alloy includes approximately 11 % of pure silicon particles by weight of the alloy.

173. An apparatus as claimed in any one of claims 166 to 172 wherein when after pure silicon has naturally segregated from the alloy, the apparatus for segregating pure silicon from the alloy is adapted for:

(ii) applying a secondary electrolysis to the tape or powder;

174. An apparatus as claimed in claim 173 wherein the apparatus for segregating pure silicon from the alloy is adapted for forming the tape by at least one of casting and extruding the alloy.

175. An apparatus as claimed in claim 174 wherein the apparatus for segregating pure silicon from the alloy is adapted for forming the powder by at least one of mechanically grinding and milling the alloy in a controlled environment.

176. An apparatus as claimed iri any one of claims 173 to 175 wherein the apparatus for segregating pure silicon from the alloy is adapted for submerging the tape or powder in an electrolyte solution during application of the secondary electrolysis.

177. An apparatus as claimed in claim 176 wherein the electrolyte solution includes at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions, hydrazoic acid (HN3), acetone, concentrated alcohol and a combination thereof.

178. An apparatus as claimed in claims 177 wherein the apparatus for segregating pure silicon from the alloy is adapted for replenishing an acidity of the electrolyte solution during application of the secondary electrolysis.

179. An apparatus as claimed in any one of claims 173 to 178 wherein the apparatus for segregating pure silicon from the alloy is adapted to apply a current of less than approximately 1 A during the secondary electrolysis.

180. An apparatus as claimed in any one of claims 176 to 179 wherein the apparatus for segregating pure silicon from the alloy is adapted for separating nano- sized pure silicon particles contained in the electrolyte solution from the electrolyte solution after the secondary electrolysis has been applied.

181. An apparatus as claimed in claim 180 wherein the apparatus for segregating pure silicon from the alloy is adapted for centrifugally separating the nano-sized pure silicon particles contained in the electrolyte solution from the electrolyte solution after the secondary electrolysis.

182. An apparatus as claimed in claims 180 or 181 wherein the apparatus for segregating pure silicon from the alloy is adapted for storing the separated nano- sized pure silicon particles in a substance which alleviates reaction with free oxygen.

183. An apparatus as claimed in claim 182 wherein the substance includes concentrated alcohol.

184. An apparatus as claimed in any one of claims 166 to 168, wherein the segregation is performed directly upon the alloy formed in the first crucible after electrolysis in accordance with any one of the method steps of claims 173 to 183.

185. A method of segregating pure silicon from an alloy containing at least one of a copper, gold, silver, zinc and a magnesium material alloyed with pure silicon particles, the method including the steps of:

(i) forming the alloy into at least one of a tape and a powder; and

(ii) applying electrolysis to the tape or powder;

whereby pure silicon particles are able to be segregated from the alloy in the form of nano-sized pure silicon particles.

186. A method as claimed in claim 185 wherein the tape is formed by at least one of casting and extruding the alloy.

187. A method as claimed in claims 185 or 186 wherein the powder is formed by at least one of mechanically grinding and milling the alloy in a controlled environment.

188. A method as claimed in claim 187 wherein the powder is formed by mechanically grinding the alloy.

189. A method as claimed in any one of claims 185 to 188 wherein the step of performing the electrolysis includes submerging the tape or powder in an electrolyte solution.

190. A method as claimed in claim 189 wherein the electrolyte solution includes at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions, hydrazoic acid (HN3), acetone, concentrated alcohol and a combination thereof.

191. A method as claimed in claim 190 including the step of replenishing an acidity of the electrolyte solution during the electrolysis.

192. A method as claimed in any one of claims 185 to 191 including the step of applying a current of less than approximately 1 A during the electrolysis.

193. A method as claimed in any one of claims 189 to 192 wherein after the electrolysis has been performed, the electrolyte solution containing the nano-sized pure silicon particles is further processed to separate the nano-sized pure silicon particles from the electrolyte solution.

194. A method as claimed in claim 193 wherein the further processing includes centrifugally separating the nano-sized pure silicon particles from the electrolyte solution.

195. A method as claimed in claims 193 or 194 wherein the separated nano-sized pure silicon particles are thereafter stored in a substance suitable for alleviating reaction with free oxygen.

196. A method as claimed in claim 195 wherein the substance includes concentrated alcohol.

197. An apparatus for segregating pure silicon from an alloy containing at least one of a copper, gold, silver, zinc and a magnesium material alloyed with pure silicon particles, the apparatus including:

(ii) an apparatus for applying electrolysis to the tape or powder;

198. An apparatus as claimed in claim 197 wherein the apparatus for forming the alloy into a tape is adapted to cast or extrude the alloy into the tape.

199. An apparatus as claimed in claims 197 or 198 wherein the apparatus for forming the powder is adapted for mechanically grinding or milling the alloy into the powder.

200. An apparatus as claimed in claim 199 wherein the apparatus for forming the powder is adapted for mechanically grinding the alloy into the powder.

201. An apparatus as claimed in claims 197 to 200 wherein the apparatus for performing the electrolysis is adapted for submerging the tape or powder in an electrolyte solution.

202. An apparatus as claimed in claim 201 wherein the electrolyte solution includes at least one of hydrochloric acid (HCI), dehydrated acetic acid, iodine solutions, hydrazoic acid (HN3), acetone, concentrated alcohol and a combination thereof.

203. An apparatus as claimed in claim 202 wherein the apparatus for performing the electrolysis is adapted for replenishing an acidity of the electrolyte solution during the electrolysis.

204. An apparatus as claimed in any one of claims 197 to 203 wherein the apparatus for performing the electrolysis is adapted for applying a voltage of less than approximately 1A during the electrolysis.

205. An apparatus as claimed in any one of claims 197 to 204 including an apparatus for separating nano-sized pure silicon particles in the electrolyte solution from the electrolyte solution.

206. An apparatus as claimed in claim 205 wherein the apparatus for separating the nano-sized pure silicon particles in the electrolyte solution from the electrolyte solution includes a centrifuge device adapted for separating the nano-sized pure silicon particles by centrifugal motion.

207. An apparatus as claimed in claims 205 or 206 including a storage apparatus for storing the separated nano-sized pure silicon particles in a substance suitable for alleviating reaction with free oxygen.

208. An apparatus as claimed in claim 207 wherein the substance includes concentrated alcohol.

209. A method of segregating pure silicon from an alloy containing at least one of a copper, gold, silver, zinc and a magnesium material alloyed with pure silicon particles, the method including the steps of:

(i) forming the alloy into at least one of a tape and a powder;

(ii) flushing the tape or powder with at least one of HCI gas and chlorine gas; and

(iii) removing CuCI₂ resulting from step (ii) by rinsing with a solution in which CuCI₂ is soluble, or, by applying a mechanical or magnetic removal process;

210. An apparatus for segregating pure silicon from any alloy containing at least one of a copper, gold, silver, zinc and a magnesium material alloyed with pure silicon particles, the apparatus for segregating pure silicon from the alloy including:

(i) an apparatus for forming the alloy into at least one of a tape and a powder;

(ii) an apparatus for flushing the tape or powder with at least one of HCI gas and chlorine gas; and

(iii) an apparatus configured for removing CuCI₂ resulting from the flushing with HCI or chlorine gas, by rinsing with a solution in which CuCI₂ is soluble, or, by applying a mechanical or magnetic removal process; whereby pure silicon particles are able to be segregated from the alloy in the form of nano-sized pure silicon particles.

211. A pure silicon produced in accordance with any one of the preceding claims.

212. A solar cell including pure silicon produced in accordance with any one of the preceding claims.

213. A battery including pure silicon produced in accordance with any one of the preceding claims.

214. A battery as claimed in claim 213 wherein an anode of the battery is formed from the pure silicon.

215. A crucible liner adapted for use in accordance with any one of the preceding claims.

216. An electrical-grade silicon material suitable for use in forming an integrated circuit element, said electrical-grade silicon material being produced in accordance with any one of the preceding claims.