DE102008010744A1 - Reduction of silica - Google Patents

Abstract

The present invention relates to a process for the reduction of silicon dioxide to silicon. The semiconductor industry has a continuing need for high purity silicon metal. Current methods for the production of high purity silicon include the reduction of silicon halides, for example, dilithium trichloride or trichlorosilane, the oxidation of silane, and the reduction of silica with elemental carbon or hydrogen. A disadvantage of several of these processes is the production of toxic or polluting by-products which cause problems of disposal and / or separation from the product. The use of hydrogen as a reducing agent requires extreme care for the exclusion of oxygen in order to avoid explosions. It is an object of the present invention to substantially overcome or at least alleviate one or more of the above disadvantages. The object is achieved by a method for producing silicon, which comprises the reaction of silicon dioxide with a reducing gas comprising carbon monoxide, wherein the reducing gas contains no elemental carbon.

Description

Technical area

The The present invention relates to a method of reducing silica to silicon.

The Semiconductor industry has a continued need for silicon metal high purity. Current procedures for the Production of high purity silicon complete the reduction of silicon halides, for example of silicon tetrachloride or trichlorosilane, the oxidation of silane and the reduction of Silica with elemental carbon or hydrogen. One Disadvantage of several of these methods is the production of toxic or polluting by-products, the problems of disposal and / or the separation from the product. The usage of hydrogen as a reducing agent requires utmost Care for the exclusion of oxygen, for explosions to avoid.

It An object of the present invention is one or more substantially overcome the above-mentioned disadvantages or at least mitigate it.

The The object is achieved by a method for the production of silicon, which is the reaction of silica with a Reduction gas comprising carbon monoxide, wherein the Reduction gas contains no elemental carbon.

In In a further development, the method comprises a step for generating of carbon monoxide by the reaction of elemental carbon with oxygen. In this case, the ratio of carbon set to oxygen so that no elemental carbon present in carbon monoxide. The ratio of carbon Oxygen is adjusted to consume all oxygen becomes. The process involves the removal of elemental carbon from the reducing gas before the step of the reaction of the silica with this. The reaction of the silicon dioxide with the reducing gas generates silicon and converts the reducing gas into an exhaust gas.

exhaust from the process are advantageously used to one Raw material for the process before using it to preheat in the process. The exhaust gas from the process will oxidizes to substantially all of the carbon monoxide contained therein convert to carbon dioxide, thereby producing oxidized exhaust gas. The Oxidized exhaust gas is also used to produce a raw material preheat the process before using it in the process. In this way, heat energy can be used during the process Oxidation process is generated, and / or heat, the Process is fed, recycled to energy consumption reduce or minimize the process and / or the energetic To improve the efficiency of the process. Furthermore reduces the oxidation of the exhaust gas its toxicity and makes it more suitable for release to the atmosphere.

Of the Step of the reaction of the silica with carbon monoxide is made in a heated reaction chamber. The temperature the heated reaction chamber is adjustable. She can both to a temperature above the melting point of silicon as also at a temperature below the boiling point of silicon and at a temperature between the melting point and the boiling point be controlled by silicon. The temperature of the heated Reaction chamber is in the range of about 1,400 and about 2,300 ° C. The reaction of the silica with carbon monoxide is at a Temperature made above the melting point of silicon. The silicon can be degassed before it solidifies.

The Silica used in the process may have a purity of at least have about 99.9 weight percent.

The The invention provides silicon obtained by the first embodiment will be produced. The silicon has a purity of at least about 99.9 percent by weight.

• • eine Kohlenstoffoxidationskammer für die Reaktion von Kohlenstoff mit Sauerstoff für die Erzeugung eines Reduktionsgases, welches Kohlenmonoxid umfasst, wobei das Reduktionsgas keinen elementaren Kohlenstoff enthält;
• • eine Reaktionskammer für die Reaktion des Reduktionsgases, das keinen elementaren Kohlenstoff enthält, mit Siliziumdioxid, wobei die Reaktionskammer mit der Kohlenstoffoxidationskammer in Verbindung steht;
• • einen Temperaturregler für das Regeln der Temperatur der Reaktionskammer;
• • eine Siliziumdioxideinlassöffnung, die mit der Reaktionskammer in Verbindung steht, um das Siliziumdioxid der Reaktionskammer zuzuführen; und
• • eine Siliziumauslassöffnung, die mit der Reaktionskammer in Verbindung steht, damit das Silizium die Reaktionskammer verlassen kann.

In addition, the object is achieved with a reactor for the production of silicon, which has the following features:

• A carbon oxidation chamber for the reaction of carbon with oxygen to produce a reducing gas comprising carbon monoxide, the reducing gas containing no elemental carbon;
• A reaction chamber for the reaction of the reducing gas containing no elemental carbon with silicon dioxide, the reaction chamber being in communication with the carbon oxidation chamber;
• A temperature controller for controlling the temperature of the reaction chamber;
• A silicon dioxide inlet port communicating with the reaction chamber to supply the silicon dioxide to the reaction chamber; and
• A silicon outlet port communicating with the reaction chamber to allow the silicon to exit the reaction chamber.

• • einen Siliziumdioxid-Vorwärmer für das Vorwärmen des Siliziumdioxids, ehe das Siliziumdioxid in die Reaktionskammer eintritt,
• • zumindest einen Vorwärmer für das Vorwärmen entweder des Kohlenstoffs oder des Sauerstoffs oder von beiden, und
• • eine Abgasauslassöffnung.

The reactor may also include a degasser for degassing the silicon after it has left the reaction chamber. It may also include one or more of the following features:

• A silicon dioxide preheater for preheating the silica before the silicon dioxide enters the reaction chamber,
• At least one preheater for preheating either the carbon or the oxygen or both, and
• • an exhaust outlet opening.

Of the Reactor can be a pipeline for the conduction of exhaust gas from the reaction chamber, or from oxidized exhaust gas, obtained by the oxidation of the exhaust gas to at least one of the preheaters for preheating at least one of the substances, of the carbon, the oxygen and the silica.

A Exhaust gas oxidation chamber may be provided for the Oxidizing carbon monoxide in the exhaust gas from the reaction chamber too Carbon dioxide to produce oxidized exhaust gas. The reaction chamber can with the exhaust gas oxidation chamber via the exhaust gas outlet keep in touch. Flow regulators can also be provided for controlling the flow of one or more of the carbon, the oxygen and the silicon dioxide. A heat storage unit may be provided which is in thermal communication with the reaction chamber.

• • Bereitstellen eines Reaktors gemäß der vorliegenden Erfindung;
• • Zuführen von Sauerstoff und Kohlenstoff zur Kohlenstoffoxidationskammer des Reaktors;
• • Reaktion des Kohlenstoffs mit dem Sauerstoff, um ein Reduktionsgas zu erzeugen, welches Kohlenmonoxid umfasst, wobei das Reduktionsgas keinen elementaren Kohlenstoff enthält;
• • Zuführen des Reduktionsgases und von Siliziumdioxid zur Reaktionskammer; und
• • Reaktion des Reduktionsgases und des Siliziumdioxids für die Herstellung von Silizium und von Abgas.

In addition, the object of the invention is achieved by a further method for the production of silicon, the method comprising the following steps:

• Providing a reactor according to the present invention;
• Supplying oxygen and carbon to the carbon oxidation chamber of the reactor;
• Reacting the carbon with the oxygen to produce a reducing gas comprising carbon monoxide, the reducing gas containing no elemental carbon;
• Supplying the reducing gas and silicon dioxide to the reaction chamber; and
• • Reaction of the reducing gas and the silicon dioxide for the production of silicon and exhaust gas.

The Method also includes oxidizing the exhaust gas to oxidized Generate exhaust gas.

Silicon, produced by this method has a purity of at least about 99.9 percent by weight.

at In the present specification, the term "silicon" is so to understand that it is based on elemental silicon or on silicon metal refers. It is understood that often uses the term "silicon metal" Although elemental silicon is a so-called semi-metal and sometimes also referred to as a metalloid.

The The present invention provides a method for the manufacture of silicon ready, which is the reaction of silica with a Reduction gas comprising carbon monoxide, wherein the Reduction gas contains no elemental carbon. It it is important that in the reducing gas no elemental carbon because carbon, under the reaction conditions, with the Silicon could react to produce silicon carbide, which that would pollute the silicon. Thus, it is possible the content of elemental carbon in the reducing gas below of about 10 ppm, or of less than about 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02 or 0.01 ppm on a molar basis relative to carbon monoxide, depending on the desired degree of purity of the silicon produced by the process.

The Reaction of the silica with the reducing gas may cause the reduction of the silica with carbon monoxide in the reducing gas with it. It can also reduce the silicon dioxide with another Component (for example, a reducing component) of the reducing gas bring with you or not. The carbon monoxide content of the reducing gas can also be any desired non-zero value, for Example of about 1 to about 100% on a weight, volume or Molbasis, or from about 10 to 100, 25 to 100, 50 to 100 or 80 to 100, for example, approximately 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, 99.5, 99.9 or 100%. The reducing gas may also comprise one or more other gases, preferably non-oxidizing gases, optionally reducing gases and / or Inert gases. The other gas (s) may / may for example nitrogen, carbon dioxide, helium, neon, argon etc. or a mixture of two or more thereof. For some Embodiments, the reducing gas contains no Hydrogen. The reducing gas may be substantially free (for Example more than about 95, 96, 97, 98, 99, 99.5 or 99.9% free) from environmental pollutants other than carbon dioxide and carbon monoxide. In some embodiments, the reducing gas is only from carbon dioxide and carbon monoxide. In other embodiments the reducing gas only from carbon dioxide, carbon monoxide and a Carrier gas. The carrier gas may be, for example, nitrogen, Be helium, neon or argon.

The method may also include the step of generating the carbon monoxide by the reaction of elemental carbon with oxygen. In this case, the ratio of acid carbon to be such that no elemental carbon is generated. The ratio of oxygen to carbon should be such that all oxygen is consumed. The ratio can be from about 2: 1 to about 1: 1 on a molar basis, or from about 2: 1 to 1.5: 1, 2: 1 to 1.8: 1, 1.5: 1 to 1: 1, 1.3: 1 to 1: 1, 1.9: 1 to 1.1: 1, 1.9: 1 to 1.5: 1, 1.5: 1 to 1.1: 1 or 1, 8: 1 to 1.3: 1, for example, about 1.1: 1, 1.2: 1, 1.3: 1, 1.4: 1, 1.5: 1, 1.6: 1, 1 , 7: 1, 1.8: 1, 1.9: 1 or 2: 1. The carbon used to produce the carbon monoxide should have a suitable particle size to allow a rapid, preferably complete reaction to carbon monoxide and optionally also carbon dioxide. The mean, or maximum, particle size of the carbon may range from about 10 microns to about 5 mm, or from about 1 micron to 1 mm, 10 to 500 microns, 10 to 100 microns, 10 to 50 microns, and 5 mm, 100 Micrometers to 5 mm, 500 micrometers to 5 mm, 1 to 5 mm, 100 to 1000 micrometers, 100 to 500 micrometers or 500 to 1000 micrometers, for example approximately 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, or 950 microns, or approximately 1, 1.5, 2, 2 , 5, 3, 3.5, 4, 4.5 or 5 mm, or in certain circumstances may be greater than 5 mm. The method may include the additional step of converting the carbon to a suitable particle size prior to the generation of the carbon monoxide. This may include milling, pelleting or any other suitable method. The carbon can be carbon of high purity. It can be at least about 99% pure, or at least about 99.5, 99.9, 99.95, 99.99, 99.995 or 99.999% pure, or 99.5 to 100, 99.9 to 100, 99.95 to 100, 99.99 to 100, 99.995 to 100, 99.999 to 100, 99.5 to 99.999, 99.9 to 99.999, 99.95 to 99.999, 99.99 to 99.999 or 99.995 to 99.999% pure, for example about 99, 99.1, 99.2, 99.3, 99, 4, 99.5, 99.6, 99.7, 99.8, 99.9, 99.95, 99.99, 99.995, 99.999 , 99.9995, 99.9999 or 100% pure.

The Carbon supply to the oxidation chamber usually becomes contain a certain amount of entrained gas. This can be air be, or it can be oxygen, carbon dioxide or another gas which is used to store the carbon in the carbon storage container to cover. The gas in the carbon storage tank should be be sufficiently pure that there are no impurities in the product Silicon introduces.

The Reaction product of the elemental carbon with the oxygen includes carbon monoxide, optionally together with carbon dioxide. Under certain Conditions may also be slightly residual elemental carbon include. In this case, the process can be the removal of the elementary Carbon from the reducing gas before the step of the reaction of the silica with this include. This can be filters, microfilters, Centrifuging, settling or other suitable method. The device for the removal of elemental carbon should be able to withstand the temperature of the reducing gas. she For example, a frit made of sintered metal or ceramic (For example, metal oxide) or another high-temperature filter device include. After the reaction of carbon and oxygen to produce of carbon monoxide, the resulting gas may be mixed with a diluent gas are mixed to produce the reducing gas. The diluent gas should not include oxidizing gas and may be a reducing gas include. Close suitable diluent gases Nitrogen, carbon dioxide, helium, neon, argon etc. or mixtures the same one. The diluent gas may be combined with the reaction product of carbon and oxygen in a ratio from about 1 to about 90 diluent gas to yield Reduction gas are mixed. The ratio can be in Range of approximately 1 and 50, 1 and 20, 1 and 10, 10 and 90, 50 and 90, 10 and 50 or 20 and 50%, for example approximately 1, 5, 10, 20, 30, 40, 50, 60, 70, 80 or 90 percent by volume. Alternatively, you can Carbon monoxide provided from a container thereof be used, for example, a commercial gas cylinder, and optionally mixed with a diluent gas, to produce the reducing gas. The kind and the relationship of the diluent gas may be as described above is. The carbon monoxide from the container can directly as the reducing gas can be used without adding a Dilution gas.

The Conditions of reaction of carbon and oxygen to Generation of carbon monoxide should be such that no violent combustion or explosion may occur. You can be such that there is a controlled oxidation of the carbon in front of him goes. The oxidation may be a combustion, preferably one controlled combustion. The conditions that should be adjusted To achieve this goal, temperature, pressure, Ratio (amount or flow rate) of carbon to oxygen, particle size of the carbon, Presence and quantity or flow rate of a diluent gas, include the design of the oxidation chamber, etc.

The reaction of the silica with the reducing gas generates silicon and converts the reducing gas to an exhaust gas. Thus, the reaction is a reduction of silicon dioxide to silicon, and represents an oxidation of the reducing gas, in particular of carbon monoxide in the reducing gas, to carbon dioxide in the exhaust gas. The exhaust gas comprises carbon dioxide, and it may also Kohlenmo oxide which has not undergone any reaction with the silica. The carbon monoxide content of the exhaust gas depends on the carbon monoxide content of the reducing gas, the ratio of the flow rate of the reducing gas to the feeding rate of silica to the reactor, the conditions (temperature, pressure, etc.) within the reactor and other factors. It can range from about 1 to about 90, or from about 1 to 80, 1 to 70, 1 to 60, 1 to 50, 1 to 20, 1 to 10, 10 to 90, 50 to 90, 10 to 50, or 20 to 50, for example, about 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85 or 90 volume percent lie.

exhaust of the process are used to provide a raw material for preheat the process before using it in the process. The preheating by the exhaust gas may be sufficient to the raw material to the desired temperature for the Entering the process, or at a temperature below the same. In the latter eventual case, an additional Heating, for example electric heating, to use the raw material to the desired To bring temperature. The exhaust gas from the process can be oxidized will be burned, for example, to essentially the entire Carbon monoxide in this convert to carbon dioxide, causing oxidized Exhaust gas is generated. The oxidized exhaust gas may be suitable for the release into the atmosphere, that is it can comply with environmental standards for carbon monoxide content. The carbon monoxide content of the oxidized exhaust gas may be below a toxic level. The carbon monoxide content of the oxidized exhaust gas may be less than about 100 ppm or less than about 50, 20 or 10 ppm, for example, about 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 ppm.

The oxidized exhaust gas can be used, at least in part or more of the raw materials for the process before use to preheat the same in the process.

The Use of the exhaust gas and / or the oxidized exhaust gas for preheating the raw materials reduces the amount of energy which must be supplied to the system to the raw materials to a suitable reaction temperature for either production of carbon monoxide or for the reduction of silica bring to.

The reaction step of the silica with carbon monoxide can be carried out in a heated reaction chamber. The temperature of the heated reaction chamber is adjustable. It can be controlled to a temperature above the melting point of silicon (1,683 K, 1,419 ° C). The temperature should not be high enough that the silicon evaporates. The boiling point of silicon is 3,173 K (2,900 ° C) ( http://www.webelements.com/Webelements/elements/text/Si/heat. html ). The temperature should be sufficient for the reduction of silica by carbon monoxide to produce silicon. For example, the temperature for the reduction of silica may be in the range of about 1,400 to about 2,300 ° C, or about 1,400 to 2,000, 1,400 to 1,700, 1,400 to 1,500, 1,500 to 2,300, 2,000 to 2,300, 1,500 to 2,200, 1,500 up to 2,000 or 1,500 to 1,800 ° C, for example, about 1,400, 1,410, 1,420, 1,430, 1,440, 1,450, 1,460, 1,470, 1,480, 1,490, 1,500, 1,550, 1,600, 1,650, 1,700, 1,750, 1,800, 1,850, 1,900, 1,950, 2,000, 2,050, 2,100, 2,150, 2,200, 2,250 or 2,300 ° C. The reduction of silicon is usually done at a pressure of about 1 atmosphere or at ambient pressure, but in some cases it can be done at a different pressure, for example in the range of about 0.5 to 10 atmospheres, or about 0.5 to 5, 0.5 to 2, 0.5 to 1, 1 to 10, 2 to 10, 5 to 10, 1 to 5 or 1 to 2 atmospheres, for example about 0.5, 0.6, 0.7 , 0.8, 0.9, 1.1, 1.2, 1.3, 1.4, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6 , 7, 8, 9 or 10 atmospheres, or at another pressure.

The flow rate of the reducing gas into the reaction chamber is adjusted so that the silica is completely reduced to silicon all the time. The reducing gas may be used in an amount (or at a corresponding flow rate) such that the molar reaction ratio of reducing components (carbon monoxide and all other reducing components of the reducing gas) to silica is at least about 1.1, or at least about 1.2, 1.3, 1.4, 1.5, 2, 2, 5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9 or 10, or about 1.1 to about 10, or about 1 , 1 to 5, 1.1 to 2, 1.5 to 10, 2 to 10, 3 to 10, 4 to 10, 5 to 10, 1.5 to 5 or 2 to 5, for example, about 1.1 , 1,2, 1,3, 1,4, 1,5, 1,6, 1,7, 1,8, 1,9, 2, 2,5, 3, 3,5, 4, 4,5 , 5, 6, 7, 8, 9 or 10, or under certain circumstances may be greater than 10 or from 1 to 1.1. In determining the above-mentioned molar reaction ratio, it is necessary to consider the oxygen content of silica. Thus, silicon dioxide (SiO ₂ ) contains two moles of oxygen per mole of silica. Accordingly, for carbon monoxide as the reducing component of the reducing gas, the actual molar ratio between silica and the reducing component will be twice the molar reaction ratio (to account for the two moles of oxygen per mole of silicon dioxide) so that a molar reaction ratio of 2 would represent a molar ratio of 4 , This is because one atom of carbon monoxide needs one atom of oxygen to produce one mole of carbon dioxide. This can be shown in the case of silica as follows become: SiO ₂ + 2CO → Si + 2CO ₂

The Silicon can be degassed before it solidifies. The method of degassing may include applying at least one include partial vacuum on the molten silicon. That, at least partial vacuum can have an absolute pressure of less than about 500 mbar or less than approximately 400, 300, 200, 100, 50, 20, 10, 5, 2 or 1 mbar, or of approximately 1, 2, 3, 4, 5, 6, 7, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450 or 500 mbar. Degassing can be the pumping of the molten silicon include, for example, to remove it from the reactor, wherein the pump used for pumping is one Kind is that an at least partial vacuum on the liquid who is pumped.

The present invention is particularly suitable for the production of silicon metal of high purity, for example for the Use in the semiconductor industry. To achieve this is the use of high purity reagents is required. In particular It is necessary that the silica of high purity is. So it is possible high-purity silicon dioxide through Conversion of the silicon dioxide to a hydrolyzable type of silicon, for Example silicon tetrafluoride gas, by purifying the hydrolyzable Silicon type and hydrolyzing the purified hydrolyzable Silicon type to produce purified silica. The silica used in the process may be of a purity of at least about 99.9 weight percent, or at least 99.95, 99.99, 99.995 or 99.999% pure, and it can be around 99.9, 99.91, 99.92, 99.93, 99.94, 99.95, 99.96, 99.97, 99.98, 99.99, 99.991, 99,992, 99,993, 99,994, 99,995, 99,996, 99,997, 99,998, 99,999, 99.9995 or 99.9999% pure. In addition, the should Conditions of reduction of silicon dioxide to silicon (temperature, CO concentration of the reducing gas, flow velocity the reducing gas, feeding rate of the silica, Particle size of the silica, etc.) is sufficient to be a complete reduction of the silica to ensure silicon.

• a) Umwandlung des Siliziumdioxids zu Siliziumtetrafluorid;
• b) Reinigung des Siliziumtetrafluorids; und
• c) Hydrolysieren des Siliziumtetrafluorids für die Herstellung von gereinigtem Siliziumdioxid, optional bei einer Temperatur, bei der Siliziumfluorsäure instabil ist.

Thus, a suitable process for the preparation of high purity silica for use in the present invention may include:

• a) conversion of the silicon dioxide to silicon tetrafluoride;
• b) purification of the silicon tetrafluoride; and
• c) hydrolyzing the silicon tetrafluoride to produce purified silica, optionally at a temperature at which silicon fluoric acid is unstable.

step a) the reaction of the silica with a mixture of hydrofluoric acid and Silicon fluoric acid to silicon tetrafluoride convert. Step b) may involve contacting the silicon tetrafluoride with a detergent. This can be done in a variety of ways Steps in a countercurrent manner. The cleaning agent may include silicon fluoric acid.

• d) Hydrolysieren eines Teils des Siliziumtetrafluorids aus Schritt b) zur Herstellung von Siliziumfluorsäure und Siliziumdioxid, und Verwendung der Siliziumfluorsäure beim Schritt b). Das Siliziumdioxid aus den Schritten c) und d) kann kombiniert werden, um das gereinigte Siliziumdioxidprodukt bereitzustellen.

The method may additionally include:

• d) hydrolyzing a portion of the silicon tetrafluoride from step b) to produce silicon fluoric acid and silica, and using the silicon fluoric acid in step b). The silica from steps c) and d) may be combined to provide the purified silica product.

impurities may be removed from the detergent after the contacting step of the silicon tetrafluoride are removed with the cleaning agent. The cleaning agent may comprise silicon fluoric acid and, after the step of contacting the silicon tetrafluoride with the silicon fluoric acid, the silicon fluoric acid converted into hydrogen fluoride and silicon tetrafluoride, whereby the hydrogen fluoride is used in step a). The Silicon tetrafluoride can either be used to silicon fluoric acid for use in step a) the hydrolyzable silicon species generated in step a) to supplement or for both. Step c) uses preferably high purity steam.

• e) Waschen des gereinigten Siliziumdioxids; und
• f) Trocknen des gereinigten Siliziumdioxids.

The method may additionally include one or both of the following steps:

• e) washing the purified silica; and
• f) drying the purified silica.

At the Step c) may be purified silica of a high temperature hydrolysis apparatus be added, in which step c) is performed. The silica may be dried prior to step a) of the process become.

• i) Schritt a) die Verwendung eines Gemisches aus Fluorwasserstoffsäure und Siliziumfluorsäure umfassen;
• ii) Schritt b) das Inkontaktbringen des Siliziumtetrafluorids mit der Siliziumfluorsäure umfassen;
• iii) Schritt c) das Hydrolysieren eines ersten Teils des Siliziumtetrafluorids aus Schritt b) unter Nutzung von Dampf für das Herstellen von gereinigtem Siliziumdioxid umfassen; und
• iv) das Verfahren kann zusätzlich umfassen:
• • das Hydrolysieren eines zweiten Teils des Siliziumtetrafluorids aus Schritt b) zur Erzeugung von Siliziumfluorsäure und gereinigtem Siliziumdioxid, wobei die Siliziumfluorsäure beim Schritt b) genutzt wird, und
• • Umwandlung der Siliziumfluorsäure aus Schritt b) zu Wasserstofffluorid und Siliziumtetrafluorid und Trocknen des Wasserstofffluorids und des Siliziumtetrafluorids, wobei das Wasserstofffluorid genutzt wird, um die bei Schritt a) genutzte Fluorwasserstoffsäure zu erzeugen, und das Siliziumtetrafluorid genutzt wird, entweder um Siliziumtetrafluorid für die Verwendung beim Schritt a) zu erzeugen oder um das bei Schritt a) erzeugte Siliziumtetrafluorid zu ergänzen, oder für beides.

In one embodiment of the process for the preparation of purified silica for use in the present invention, therefore

• i) step a) comprise the use of a mixture of hydrofluoric acid and silicon fluoric acid;
• ii) step b) comprising contacting the silicon tetrafluoride with the silicon fluoric acid;
• iii) step c) hydrolyzing a first part the silicon tetrafluoride from step b) using steam to produce purified silica; and
• iv) the method may additionally include:
• Hydrolyzing a second part of the silicon tetrafluoride from step b) to produce silicon fluoric acid and purified silicon dioxide, the silicon fluoric acid being used in step b), and
• Conversion of the silicon fluoric acid from step b) to hydrogen fluoride and silicon tetrafluoride and drying the hydrogen fluoride and silicon tetrafluoride, wherein the hydrogen fluoride is utilized to generate the hydrofluoric acid used in step a) and the silicon tetrafluoride is used, either silicon tetrafluoride for use in the Step a) or to supplement the silicon tetrafluoride produced in step a), or both.

The Particle size of the present invention used silicon dioxide is commonly in the diameter range from about 10 to about 2,000 microns. Usually are Silica particles not spherical. Thus, in this Context "diameter" to a maximum cross-section of particles or to a minimum transverse particle size or to a middle particle size Particle transverse extent or to a hydrodynamic diameter refer. The diameter can be in the range of about 10 to about 2,000 microns, or from about 10 to 1,000, 10 to 500, 10 to 200, 10 to 100, 10 to 50, 10 to 20, 50 to 2,000, 100 to 2,000, 500 to 2,000, 1,000 to 2,000, 1,500 to 2,000, 50 to 1,000, 50 to 500, 50 to 200, 100 to 1,000, 100 to 500 or 500 up to 1,000 microns, for example, about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1,000, 1,100, 1,200, 1,300, 1,400, 1,500, 1,600, 1,700, 1,800, 1,900 or 2,000 microns, or he can get bigger be about 2,000 microns. The diameter described here may be for a medium (number average or weight average) diameter or a maximum diameter.

The Silica feed to the reaction chamber usually becomes contain some entrained gas, which will be the gas that is used to the silicon dioxide in Siliziumdi oxide storage tank cover. It is preferable that this gas is a non-oxidizing Gas is an extra amount because of the presence of an oxidizing gas Reduction gas during the reduction of the silicon dioxide would consume. Thus, the silicon dioxide storage container with a non-oxidizing gas, optionally a reducing gas, be covered, for example nitrogen, carbon dioxide, carbon monoxide, Argon, helium or a combination thereof. If the silicon dioxide produced locally and as produced silicon dioxide instead As stored silica is used, any of the above mentioned non-oxidizing gases, optionally reducing gases, be used for the silicon dioxide to the reaction chamber to transport.

The The invention also provides silicon prepared according to the Method of the invention is produced. The silicon can be one Have purity of at least 99.9 weight percent. The purity can be at least about 99.9 percent by weight, or it can at least 99.95, 99.99, 99.995 or 99.999% pure, and purity can be at about 99.9, 99.91, 99.92, 99.93, 99.94, 99.95, 99.96, 99.97, 99.98, 99.99, 99.991, 99.992, 99.993, 99.994, 99.995, 99.996, 99.997, 99.998, 99.999, 99.9995 or 99.9999%. It may be sufficient of one high purity for use in the semiconductor industry be. Not only is it necessary to achieve this purity to ensure that the silica of sufficient high purity, but also that the reactor for The production of silicon is made from materials that the silicon, once it has been produced, does not pollute it. These materials can include metals, For example, steel, stainless steel, titanium, etc., which the from Raktor does not pollute silicon. The materials can be pretreated, for example washed, heated etc. be used to remove or contaminate potential pollutants to reduce.

The The present invention also provides a reactor which for carrying out the process of the invention suitable is. The reactor comprises a carbon oxidation chamber and a reaction chamber connected to the carbon oxidation chamber communicates. The reaction chamber is equipped with a Temperature controller for regulating the temperature inside the reaction chamber, and it has a silicon dioxide inlet and a silicon outlet opening.

The carbon oxidation chamber includes an inlet port for receiving carbon and / or oxygen, and may have separate carbon and oxygen inlet ports. It may also include an inlet port or other device for receiving a diluent gas into the carbon oxidation chamber. Alternatively, the diluent gas inlet port, if present, may be arranged so that the diluent gas may be combined with the oxidation product obtained from the carbon and oxygen in the carbon oxidation chamber. The carbon oxidation chamber may be heated to facilitate the conversion of carbon and silica therein to carbon monoxide. Thus, the reactor may be a heater for the Heating the carbon oxidation chamber. It may include a regulator for controlling the temperature of the carbon oxidation chamber. In some embodiments, the carbon oxidation chamber at least partially surrounds the reaction chamber. In this design, heat generated in the oxidation chamber by the partial oxidation of carbon to carbon monoxide can be used to heat the reaction chamber, optionally with the aid of an intermediate heat storage material, such as graphite. An advantage of graphite as a heat storage material is that it has a high melting point and high heating capacity and increasing heating capacity with increasing temperature. It is understood that other materials with a high heating capacity can also be used. It is preferred that the outside of the oxidation chamber be well insulated to minimize heat loss by radiation. This also improves the safety of the reactor. A suitable design involves an oxidation chamber having an annular cross-section surrounding a reaction chamber in the core of the ring mold. Thus, the oxidation chamber may be a cylinder having a hollow core containing the reaction chamber. It is understood that the cross section of the oxidation chamber may have a square, rectangular, pentagonal, hexagonal, etc. shape with a core region for the reaction chamber.

Of the Temperature controller for controlling the temperature of the carbon oxidation chamber can be the same as the one for regulating the temperature inside the reaction chamber. The reaction chamber can be inside or partly within a heating block. The carbon oxidation chamber may be inside or partly within a heating block, which may be the same or different than the heating block, in the reaction chamber is located. Thus are with a Embodiment, both the reaction chamber and the Carbon oxidation chamber within a heating block. The heating block can a temperature controller for regulating the temperature of the Heating block and thus for the regulation of the temperature within the reaction chamber and within the carbon oxidation chamber exhibit. The temperature of the heating block can be controlled by a heating block regulator which, for example, a thermostat, an electric Heating element, a non-electric heater and / or others Components may include. The heating block can expediently Carbon, for example graphite, as a heat storage medium.

Of the Reactor may be a silica feed system for comprise the provision of silicon dioxide to the reaction chamber. The silica delivery system may communicate with the silica inlet port the reaction chamber communicate. The silica delivery system may be a silicon dioxide storage container or a silicon dioxide generator include, for example, a generator of high purity silica or a silicon dioxide cleaner. The silica delivery system Optionally, a device for reducing the particle size include (for example, a crusher, a crusher, a grinder etc.), for reducing the particle size of the silica to a size suitable for a feeder for the process is. The silica delivery system can also a silicon dioxide preheater. Energy for the preheater can be provided by hot Exhaust gas from the reaction chamber or by hot oxidized Exhaust gas from the exhaust gas oxidation chamber or both. The silica delivery system may also have one or more suitable conveyors, if necessary, for the transport of silicon dioxide from the silica source to the silicon dioxide preheater and from the silicon dioxide preheater to the reaction chamber. The conveyors can be suitable pipes, hoses and conveying devices. conveyors can conveyers, screw conveyors and / or other suitable devices.

The Silicon outlet opening of the reaction chamber can with a Silicon storage chamber for collecting silicon, the generated in the reaction chamber, communicate. Conveniently, the silicon outlet is at or near the silicon outlet Bottom of the reaction chamber, and the silicon collection chamber is located extending below the silicon outlet opening so that in the Reaction chamber produced molten silicon by gravity through the silicon outlet opening to the silicon collection chamber can happen. The silicon collecting chamber can also be at a Temperature of the melting point of silicon or above it held to the silicon in molten or liquid To maintain state. It can with a heater and / or a be equipped with suitable insulation to keep them at that temperature to keep.

The reactor may also include a degasser for degassing the silicon after it leaves the reaction chamber. The degasifier may be attached to the silicon collection chamber so that the silicon is degassed while in the liquid state. The degasser may conveniently comprise a pump which controls the pressure on the liquid silicon in the process of its transfer from the silicon collection chamber, for example to a solidification device, for the conversion of the degassed ge reduced silicon to solid silicon.

Of the Reactor may also have a silicon dioxide preheater for preheating the silica before the silicon dioxide enters the reaction chamber, and / or at least one preheater for preheating either the carbon or the oxygen or both. One of the preheaters or both preheaters can have a heat exchanger for the transfer of heat from the exhaust gas and / or the oxidized exhaust gas to the silica and / or on include the carbon and / or the oxygen. The reactor can be a suitable conduit for the discharge of exhaust gas from the reaction chamber or from oxidized exhaust gas passing through Oxidation of the exhaust gas was obtained, at least one of these Include preheater. The preheater for the preheating of the oxygen may be suitable for heating the oxygen to a suitable temperature for the oxidation of carbon to carbon monoxide or to a temperature below the oxidation temperature for carbon. He can bring the oxygen to a temperature of about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more than about 100 ° C below to heat the oxidation temperature for carbon. Similarly, the preheater for the preheating of the carbon be suitable for heating the carbon to a suitable temperature for the oxidation of carbon to carbon monoxide or on a temperature below the oxidation temperature for Carbon. He can bring the carbon to a temperature of about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more than about 100 ° C Heat below the oxidation temperature for carbon. The preheater for preheating the silicon dioxide can be suitable for preheating the silicon dioxide to a temperature of about the one responsible for the reaction of silica with carbon monoxide for generation of the silicon is required, or to a temperature of about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more than about 100 ° C below that temperature.

A Exhaust gas oxidation chamber may be provided for the Oxidizing carbon monoxide in exhaust gas from the reaction chamber too Carbon dioxide to produce oxidized exhaust gas. Flow Controllers can also for regulating the flow one or more of the carbon, the oxygen and the silicon dioxide to be provided. A heat storage unit may be provided which is in thermal communication with the reaction chamber.

By the use of silica and carbon, both with one very high degree of purity, it is possible by direct Reduction at about the melting temperature of silicon, silicon metal to produce with a comparably high degree of purity.

• a) einen Reaktor für die Umwandlung des Siliziumdioxids in Siliziumtetraf1uorid;
• b) einen ersten Reiniger für das Reinigen des Siliziumtetrafluorids unter Nutzung eines Reinigungsmittels; und
• c) eine Hydrolysevorrichtung (zum Beispiel eine Hochtemperaturhydrolysevorrichtung) für das Hydrolysieren des Siliziumtetrafluorids zur Herstellung von gereinigtem Siliziumdioxid, optional bei einer Temperatur, bei der Siliziumfluorsäure instabil ist.

Accordingly, a reactor for the production of silica according to the present invention may additionally comprise a system for purifying silica. Thus, it may comprise a system for purifying silica which comprises:

• a) a reactor for the conversion of silicon dioxide into Siliciumtetraf1uorid;
• b) a first cleaner for purifying the silicon tetrafluoride using a cleaning agent; and
• c) a hydrolysis device (for example, a high temperature hydrolysis device) for hydrolyzing the silicon tetrafluoride to produce purified silica, optionally at a temperature at which silicon fluoric acid is unstable.

• d) eine Niedrigtemperaturhydrolysevorrichtung für das Hydrolysieren eines Teils der gereinigten hydrolysierbaren Siliziumart vom ersten Reiniger, für die Herstellung des Reinigungsmittels und des Siliziumdioxids und
• e) eine Ablenkvorrichtung für das Ablenken des Teils der gereinigten hydrolysierbaren Siliziumart zur Niedrigtemperaturhydrolysevorrichtung.

The system may additionally include:

• d) a low temperature hydrolysis apparatus for hydrolyzing a portion of the purified hydrolyzable silicon species from the first cleaner, for the preparation of the detergent and the silica, and
• e) a deflector for deflecting the portion of the purified hydrolyzable silicon species to the low temperature hydrolysis apparatus.

Of the first cleaner can be a multi-stage countercurrent cleaner. The System may also include a second cleaner, for example a distiller, for the removal of impurities from the detergent. The second cleaner can also have one Include water remover. A cleaner recycling system can also be provided to purified issue from the second cleaner to lead to the reactor. The system can also have one Producer of high purity steam for generating High purity steam, wherein the producer of steam is high Purity with the high temperature hydrolysis apparatus for the provision of high purity steam to the high temperature hydrolysis apparatus communicates. It may also be a detergent delivery system for passing the detergent from the second hydrolysis device to the first cleaner.

• f) eine Waschvorrichtung für das Waschen des gereinigten Siliziumdioxids; und
• g) ein Trockengerät für das Trocknen des gereinigten Siliziumdioxids.

The system may additionally include one or both of the following:

• f) a washing device for washing the purified silica; and
• g) a drying device for drying the purified silica.

• • eine Niedrigtemperaturhydrolysevorrichtung für das Hydrolysieren eines zweiten Teils des gereinigten Siliziumtetrafluorids aus dem ersten Reiniger, um Siliziumfluorsäure und Siliziumdioxid herzustellen;
• • eine Ablenkvorrichtung für das Ablenken des Teils des gereinigten Siliziumtetrafluorids zur Niedrigtemperaturhydrolysevorrichtung;
• • ein Destilliergerät für das Entfernen von Verunreinigungen aus der Siliziumfluorsäure vom ersten Reiniger und für das Umwandeln der Siliziumfluorsäure zu Wasserstofffluorid und Siliziumtetrafluorid;
• • ein Trockengerät für das Entfernen von Wasser aus dem Wasserstofffluorid und dem Siliziumtetrafluorid aus dem Destilliergerät; und
• • ein Reiniger-Recyclingsystem für das Leiten von Wasserstofffluorid und Siliziumtetrafluorid vom Trockengerät zum Reaktor.

The high temperature hydrolysis apparatus may comprise a silicon dioxide inlet port. A pre-dryer can be provided for the Pre-drying the silica before the silicon dioxide enters the reactor. The system may additionally include:

• A low temperature hydrolysis device for hydrolyzing a second portion of the purified silicon tetrafluoride from the first purifier to produce silicon fluoric acid and silica;
• A deflector for deflecting the portion of the purified silicon tetrafluoride to the low temperature hydrolysis apparatus;
• A distiller for removing impurities from the silicon fluoric acid from the first purifier and for converting the silicon fluoric acid to hydrogen fluoride and silicon tetrafluoride;
• A drying device for removing water from the hydrogen fluoride and silicon tetrafluoride from the distiller; and
• A cleaner recycling system for passing hydrogen fluoride and silicon tetrafluoride from the dryer to the reactor.

A preferred embodiment of the present invention in the following, by way of example only, with reference to the accompanying drawings described.

It shows:

1 a graphical, schematic representation of the method and the reactor according to the present invention.

A suitable reactor 10 for the production of silicon according to the present invention is described in 1 shown. In 1 includes the reactor 10 a carbon oxidation chamber 20 that with a reaction chamber 30 communicates. The oxidation chamber 20 is with an oxygen inlet opening 35 and a carbon inlet port 40 fitted. The reaction chamber 30 is equipped with a temperature controller 50 , with an inlet pipe 55 and an outlet conduit 60 for passing a heat transfer material to the regulator 50 and away from this, to the temperature of the reaction chamber 30 to regulate. The reaction chamber 30 also has a silicon dioxide inlet port 70 , a silicon outlet 75 and an exhaust outlet opening 80 , The silicon outlet opening 75 stands with a silicon collection chamber 90 in connection. The collection chamber 90 is with a pump 100 equipped, which can serve both to degas molten silicon after it enters the reaction chamber 30 has left as well as to this from the reactor 10 (that is, from the collection chamber 90 of the reactor 10 ) to pump out. The oxidation chamber 20 , the reaction chamber 30 and the collection chamber 90 they are all inside a heating block 110 Conveniently, a block of carbon to maintain the temperature in these chambers. The block 110 is temperature controlled by the regulator 50 , Carbon is particularly suitable as a material for use in the heating block 110 , due to its high thermal conductivity and temperature-increasing heating capacity.

The reactor 10 also includes a silica delivery system 120 , The delivery system 120 includes a silica storage container 125 and a silicon dioxide preheater 130 , together with conveyors 135 and 140 for conveying silica from the container 125 to the preheater 130 or from the preheater 130 to the inlet opening 70 , The conveyors 135 and 140 are expediently conveyor devices of the screw type, which allow the silicon dioxide from the container 125 in the reaction chamber 30 transporting pollutants, for example from the atmosphere, to a minimum. Similarly, the storage container 125 designed so as to avoid contamination of the high purity silica feed therein. In some embodiments of the invention, the storage container 125 be replaced by a device for the production of high purity silica, whereby the silica the feed system 120 is fed continuously as it is generated.

The reactor 10 also includes a carbon delivery system 150 holding a carbon storage container 160 which is arranged for the supply of carbon to a carbon preheater 170 , An oxygen delivery system 180 includes an oxygen source 190 , which is arranged for the supply of oxygen to an oxygen preheater 200. , The oxygen source 190 may be an oxygen tank, or it may be an oxygen generator, for example a membrane-based oxygen or chemical based oxygen generator.

The reactor 10 further comprises an exhaust gas oxidation chamber 210 for oxidizing carbon monoxide in exhaust gas from the reaction chamber 30 to carbon dioxide to produce oxidized exhaust gas.

• 1) Anthrazitkohle kann zu extrem hohen Graden der Reinheit veredelt werden. Unter der Voraussetzung, dass es in Reinsystemen gehandhabt und gelagert wird, kann sie beim Reduktionsverfahren der vorliegenden Erfindung verwendet werden. Sie kann im Kohlenstofflagerbehälter 160 gelagert werden.
• 2) Es ist möglich, Trocken-Siliziumkristalle von extrem hoher Reinheit verfügbar zu haben. Da diese Kristalle scheuernd sind, müssen die Lagerung und die Handhabung mit Sorgfalt erfolgen. Das reine Siliziumdioxid wird wird im Siliziumdioxidlagerbehälter 125 gelagert. Das Siliziumdioxid kann unter Einsatz des Verfahrens der gleichzeitig anhängigen Anmeldung mit dem Titel „Reinigung von Siliziumdioxid” erzeugt werden.
• 3) Der Siliziumdioxidvorwärmer 130 kann mit Siliziumkarbid oder mit einem anderen geeigneten temperaturbeständigen Material ausgekleidet sein. Der Vorwärmer 130 kann mit Hilfe der Verbrennung von Abgasen aus der Reaktionskammer 30 erwärmt werden, um das reine Siliziumdioxid für die Injektion in die Reaktionskammer 30 vorzuwärmen.
• 4) Der Sauerstoffvorwärmer 200 ist eine Wärmeaustauscheinheit, die für das Vorwärmen des benötigten Verbrennungssauerstoffes ausgelegt ist. Es kann zweckmäßigerweise durch Abgase erwärmt werden, welche die Reaktionskammer 30 verlassen.
• 5) Der Kohlenstoffvorwärmer 170 ist ein Wärmespeichersystem, das mit glattem Siliziumkarbid oder mit einem anderen wärmbeständigen Material ausgekleidet ist und durch die Verbrennungsabwärme von der Oxidation des Abgases aus der Reaktionskammer 30 erwärmt wird. Der Vorwärmer 170 ist ausgelegt für das Vorwärmen des reinen Kohlenstoffmaterials vor dessen Injektion in die Oxidationskammer 20.
• 6) Die Oxidationskammer 20 ist ein wichtiger Teil des Systems, in welchem das Gleichgewicht zwischen dem vorgewärmten Kohlenstoff und dem vorgewärmten Sauerstoffgas geregelt wird, um zu gewährleisten, dass keine genügende Menge an Sauerstoff für das Erzeugen von CO₂ sowie kein freier Kohlenstoff im Verbrennungszyklus vorhanden sind. Die Oxidationskammer 20 umgibt die Reaktionskammer 30 und leitet ihre Wärme zum Wärmespeichermaterial zwischen der Verbrennungskammer und der Reaktorkammer. Somit kann die Oxidationskammer 30 ringförmig sein, oder sie kann eine ähnliche Form haben, jedoch mit einem rechteckigen, quadratischen, fünfeckigen, sechseckigen oder einem ähnlichen Querschnitt.
• 7) Die Reaktionskammer 30 wird durch ein Wärmespeichersystem auf eine Temperatur von zirka 1.410°C geregelt. In der Reak torkammer 30 umfasst das Reduktionsgas CO. Das CO reagiert, um O₂ aus dem SiO₂ zu entfernen, wodurch CO₂ erzeugt wird, welches das Silizium frei in hoher Reinheit läßt, um als eine Flüssigkeit in die Sammelkammer 90 über die Auslassöffnung 75 zu fallen.
• 8) Für die Regelung der Temperatur in der Reaktionskammer 30 auf der korrekten Temperatur für die Reaktion wird eine Graphit-Wärmespeichereinheit 220 verwendet. Diese Einheit wird durch die Oxidation des Kohlenstoffs durch Sauerstoff zu CO in der Oxidationskammer 20 erwärmt, und ihre Wärme wird genau durch den Temperaturregler 50 geregelt.
• 9) Um die Wärme zurückzuhalten, ist eine Außenfläche 230, welche die Oxidationskammer 20 umgibt, stark isoliert.
• 10) Das im Verfahren erzeugte Silizium wird in der Sammelkammer 90 unterhalb der Reaktionskammer 30 gesammelt.
• 11) Da in der Struktur des Siliziums etwas CO oder CO₂ vorliegen kann, werden ein Zwischenpumpen, und eine Vakuumgasextraktion eingesetzt, um alle Gase zu entfernen.
• 12) Da das Verfahren der Erfindung auf der Grundlage von reinem Hochtemperatur-Kohlenmonoxid beruht, das mit dem Siliziumdioxid reagiert, wird ein Überschuss an Kohlenmonoxid im CO₂ vorliegen, welches aus der Reaktionskammer 30 austritt. In der Kammer 210 (mit Wärmetauscherfunktion) wird zusätzliche Luft oder Sauerstoff hinzugefügt, die mit dem CO reagiert, um CO₂ auszubilden und gleichzeitig dem oxidierten Abgas Wärme hinzufügt, die dann für das Vorwärmen des Siliziumdioxids/Kohlenstoffs/Sauerstoffs, die im Verfahren verwendet werden, genutzt werden kann.
• 13) Der Temperaturregler 50 ist ein wärmegeregeltes System, das thermisch mit der Reaktionskammer 30 verbunden ist und ei ne verfügbare Wasserkühlung hat, die nach Bedarf durch die Leitungen 55 und 60 verläuft.
• 14) Um ein reines Produkt aus dem Verfahren zu erzeugen, ist die Innenauskleidung der Oxidationskammer 20, der Reaktionskammer 30 und der Sammelkammer 90 mit Hochqualitäts-Oberflächen-Siliziumkarbid ausgekleidet, das hohe Wärmeübertragungsmerkmale aufweist und so konstruiert werden muss, um sich mit der Wärmespeichereinheit 220 zu verbinden, um eine wirksame Wärmeübertragung zu ermöglichen.

Aspects of an embodiment of the invention are as follows:

• 1) Anthracite coal can be upgraded to extremely high levels of purity. Provided that it is handled and stored in pure systems, it can be used in the reduction process of the present invention. It can in carbon storage tank 160 be stored.
• 2) It is possible to have dry silicon crystals of extremely high purity available. This one Crystals are scouring, storage and handling must be done with care. The pure silica will be in the silicon dioxide storage tank 125 stored. The silica may be produced using the method of co-pending application entitled "Purification of Silica".
• 3) The silicon dioxide preheater 130 may be lined with silicon carbide or another suitable temperature resistant material. The preheater 130 can with the help of the combustion of exhaust gases from the reaction chamber 30 are heated to the pure silica for injection into the reaction chamber 30 preheat.
• 4) The oxygen preheater 200. is a heat exchange unit designed to preheat the required combustion oxygen. It may conveniently be heated by exhaust gases containing the reaction chamber 30 leave.
• 5) The carbon preheater 170 is a heat storage system lined with smooth silicon carbide or other heat resistant material and by the waste heat of combustion from the oxidation of the exhaust gas from the reaction chamber 30 is heated. The preheater 170 is designed for preheating the pure carbon material prior to its injection into the oxidation chamber 20 ,
• 6) The oxidation chamber 20 is an important part of the system in which the balance between the preheated carbon and the preheated oxygen gas is controlled to ensure that there is not enough oxygen to produce CO ₂ and no free carbon in the combustion cycle. The oxidation chamber 20 surrounds the reaction chamber 30 and directs its heat to the heat storage material between the combustion chamber and the reactor chamber. Thus, the oxidation chamber 30 be annular, or they may have a similar shape, but with a rectangular, square, pentagonal, hexagonal or a similar cross-section.
• 7) The reaction chamber 30 is controlled by a heat storage system to a temperature of about 1,410 ° C. In the reactor chamber 30 For example, the reducing gas comprises CO. The CO responds to remove O ₂ from the SiO _2, thereby producing CO _2, which can be the silicon-free in high purity to as a liquid into the collection chamber 90 over the outlet opening 75 to fall.
• 8) For regulating the temperature in the reaction chamber 30 at the correct temperature for the reaction becomes a graphite heat storage unit 220 used. This unit becomes CO in the oxidation chamber due to the oxidation of carbon by oxygen 20 heated, and their heat is precisely through the temperature controller 50 regulated.
• 9) To retain the heat is an outer surface 230 which the oxidation chamber 20 surrounds, strong isolated.
• 10) The silicon generated in the process is in the collection chamber 90 below the reaction chamber 30 collected.
• 11) As there may be some CO or CO ₂ in the structure of the silicon, an intermediate pumping and a vacuum gas extraction are used to remove all the gases.
• 12) Since the process of the invention is based on pure high temperature carbon monoxide which reacts with the silica, there will be an excess of carbon monoxide in the CO ₂ coming from the reaction chamber 30 exit. In the chamber 210 (with heat exchanger function) additional air or oxygen is added which reacts with the CO to form CO ₂ and at the same time adds heat to the oxidized exhaust which can then be used for the preheating of the silica / carbon / oxygen used in the process ,
• 13) The temperature controller 50 is a thermoregulated system that works thermally with the reaction chamber 30 is connected and has any available water cooling, as needed through the pipes 55 and 60 runs.
• 14) To produce a pure product from the process, the inner lining of the oxidation chamber 20 , the reaction chamber 30 and the collection chamber 90 lined with high quality surface silicon carbide, which has high heat transfer characteristics and must be designed to interact with the heat storage unit 220 connect to allow for efficient heat transfer.

The reactor of 1 can be operated as follows. Oxygen comes from the source 190 the preheater 200. fed and is from there through the inlet opening 35 through to the oxidation chamber 20 guided. High purity carbon in powder or granular form is in the container 160 stored and goes from the container 160 over the preheater 170 through the inlet opening 40 through to the oxidation chamber 20 , Conveying means, for example screw conveyors, can be used to convey the carbon as described. preheater 170 and 200. heat the carbon or oxygen to temperatures that are suitable for rapid reaction in the chamber 20 to allow. In the chamber 20 For example, the carbon is partially oxidized to form a reducing gas which primarily contains carbon monoxide, although some carbon dioxide may also be present. The delivery rates of oxygen and carbon in the Kam mer 20 are preferably adjusted to ensure that the carbon is completely converted so that no elemental carbon to the reaction chamber 30 and also to ensure that the reducing gas contained in the chamber 20 produced by the partial oxidation of the carbon, does not contain any free oxygen. The oxidation reaction in the chamber 20 Provides thermal energy through the heat storage unit 220 is transported to the reaction chamber 30 to warm up. That in the chamber 20 produced reducing gas also passes into the lower portion of the reaction chamber 30 ,

High purity silica becomes in the container 125 stored, protected against pollutants. It passes from there to the silicon dioxide preheater 130 which raises its temperature to allow for its reduction. It then passes with the help of the conveyor 140 through the inlet opening 70 through into the upper part of the reaction chamber 30 , Thus rises in the chamber 30 Reduction gas upwards, while silica moves down in a countercurrent relative to the reducing gas. When the silicon dioxide is in the reaction chamber 30 moved down, it is reduced by the reducing gas to silicon. The reaction chamber 30 is preferably maintained at a temperature between the melting point of silicon dioxide and the melting point of silicon. This can be achieved by the heat generated by the oxidation reaction in the chamber 20 is provided, along with cooling, if necessary, by the regulator 50 provided. Thus, the silicon is formed as a liquid located on the bottom of the chamber 30 precipitates and through the outlet opening 75 through into the collection chamber 90 flows. The pump 100 then pumps the liquid silicon to a storage location (not in 1 shown) and thereby degassing the liquid silicon by removing residual carbon monoxide and / or carbon dioxide. The silicon produced in this process is of high purity and care should be taken to avoid downstream contamination of the product.

When the reducing gas reduces the silica to silicon, it is itself oxidized to produce carbon dioxide. Thus, the exhaust gas, which from the chamber 30 leaked, a mixture of carbon dioxide with carbon monoxide, which was not subject to any reaction. This gas has a high temperature and it becomes a preheater 200. where some of its heat energy is transferred to the oxygen, which is the oxidation chamber 20 is supplied. The exhaust gas then goes to the exhaust gas oxidation chamber 210 , which is also equipped with an air or oxygen inlet. Thus, in the chamber 210 the exhaust gas is oxidized, converting carbon monoxide, which has not reacted, to carbon dioxide. This generates extra heat energy, which warms the oxidized exhaust gas. The oxidized exhaust gas then goes to the silicon dioxide preheater 130 to the silicon dioxide of high purity, which is the reaction chamber 30 is fed, to warm. The oxidized exhaust gas then goes to the carbon preheater 170 where it is used to warm the carbon, which is the oxidation chamber 20 is supplied. The resulting oxidized exhaust gas has a very low content of carbon monoxide and a relatively moderate temperature, and is therefore suitable for venting to the atmosphere.

10

reactor

20

Carbon oxidation chamber

30

reaction chamber

35

Oxygen inlet port

40

Carbon inlet port

50

thermostat

55

inlet line

60

outlet pipe

70

Siliziumdioxideinlassöffnung

75

Siliziumauslassöffnung

80

exhaust port

90

Silicon collection chamber

100

pump (Vacuum gas extraction)

110

heating block

120

Siliziumdioxidzuführungssystem

125

Siliziumdioxidlagerbehälter

130

Siliziumdioxidvorwärmer

135

conveyor

140

conveyors

150

Carbon feed system

160

Carbon storage containers

170

Kohlenstoffvorwärmer

180

Oxygen supply system

190

oxygen source

200

Sauerstoffvorwärmer

210

Exhaust gas oxidation chamber

220

Graphite heat storage unit

230

outer surface

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - http://www.webelements.com/Webelements/elements/text/Si/heat. html [0028]

Claims (21)

A method of producing silicon comprising reacting silica with a reducing gas comprising carbon monoxide, characterized in that the reducing gas does not contain elemental carbon. The method of claim 1, comprising the step the generation of the reducing gas by the reaction of elemental Carbon with oxygen. A method according to claim 1 or claim 2, characterized characterized in that exhaust gas from the process is used to to preheat a raw material for the process. Method according to one of claims 1 to 3, characterized in that oxidized exhaust gas from the process to substantially all of the carbon monoxide contained therein convert to carbon dioxide, thereby producing oxidized exhaust gas. Method according to one of claims 1 to 4, characterized in that the oxidized exhaust gas is used, to preheat a raw material for the process. Method according to one of claims 1 to 5, characterized in that the step of the reaction of the silicon dioxide with the reducing gas within a heated reaction chamber is carried out. The method of claim 6, additionally comprising controlling the temperature of the heated reaction chamber. Method according to one of claims 1 to 7, characterized in that the step of the reaction of the silica with the reducing gas at a temperature above the melting point made of silicon. Method according to claim 8, characterized in that that the silicon is degassed before it solidifies. Method according to one of claims 1 to 9, characterized in that the silica is a purity of at least about 99.9 weight percent. Silicon produced by the method according to Claims 1 to 10. The silicon of claim 11, wherein the silicon is a Purity of at least about 99.9 weight percent. Reactor for the production of silicon, comprising: a carbon combustion chamber ( 20 for the reaction of carbon with oxygen to produce a reducing gas comprising carbon monoxide, the reducing gas containing no elemental carbon; A reaction chamber ( 30 ) for the reaction of the reduction gas, which contains no elemental carbon, with silicon dioxide, wherein the reaction chamber ( 30 ) with the carbon combustion chamber ( 20 ); • a temperature controller ( 50 ) for controlling the temperature of the reaction chamber ( 30 ); A silicon dioxide inlet opening ( 70 ), which communicate with the reaction chamber ( 30 ) for the supply of the silicon dioxide to the reaction chamber ( 30 ); and a silicon outlet opening ( 75 ), which communicate with the reaction chamber ( 30 ) so that the silicon is the reaction chamber ( 30 ) can leave. Reactor according to claim 13, additionally comprising a deaerator for the degassing of the silicon, after it has the reaction chamber ( 30 ) has left. Reactor according to claim 13 or claim 14, additionally comprising a silicon dioxide preheater ( 130 ) for the preheating of the silicon dioxide, before the silicon dioxide in the reaction chamber ( 30 ) entry. Reactor according to one of claims 13 to 15, additionally comprising at least one preheater ( 170 . 200. ) for preheating either the carbon or the oxygen or both. Reactor according to claim 15 or claim 16, comprising a pipeline for the passage of exhaust gas from the reaction chamber ( 30 ), or oxidized exhaust gas obtained by the oxidation of the exhaust gas, or both, to at least one of the preheaters ( 130 . 170 . 200. ) for preheating at least one of the carbon, the oxygen and the silica. Reactor according to one of claims 13 to 17, comprising an exhaust gas combustion chamber ( 180 for oxidizing carbon monoxide in the exhaust gas from the reaction chamber to carbon dioxide to produce oxidized exhaust gas. Reactor according to one of claims 13 to 18, additionally comprising one or more flow regulators for regulating the flow of carbon, oxygen and silica. Reactor according to one of claims 13 to 19, characterized in that the reaction chamber ( 30 ) is in thermal communication with a heat storage unit. Method for producing silicon, the method comprises: • Provide a Reactor, wherein the reactor comprises a carbon combustion chamber for the reaction of carbon with oxygen to produce a reducing gas comprising carbon monoxide, wherein the reducing gas contains no elemental carbon; Provide one Reaction chamber for the reaction of the reducing gas, the contains no elemental carbon, with silicon dioxide, wherein the reaction chamber with the carbon combustion chamber communicates; a temperature controller for the rules the temperature of the reaction chamber; a silicon dioxide inlet opening, which is in communication with the reaction chamber for the Feeding the silicon dioxide to the reaction chamber; and a silicon outlet opening connected to the reaction chamber so that the silicon leaves the reaction chamber can; • Supply of oxygen and carbon to the carbon combustion chamber; • Reaction of the Carbon with the oxygen for generating a Reduction gas comprising carbon monoxide, wherein the reducing gas contains no elemental carbon; • Respectively the reducing gas and the silicon dioxide to the reaction chamber; and • Reaction of the reducing gas and the silicon dioxide for the production of silicon and exhaust gas.